Question

Given below are two statements:

Statement (I): Chute spillways carry the flow down the steep slopes through a lined channel rather than by dropping the water in a free overfall.

Statement (II): On steep slopes, chutes are more economical than series of drop structures to take the flow down the slope.

In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Compare how a chute channels water down a slope versus how a stepped series of drop structures would, and weigh the construction cost of each.

Answer 1

The Correct Option is A

Step 1: Recall the working definition of a chute spillway: it is a spillway that carries the discharge down a steep slope through an open, lined channel (a chute or trough), instead of letting the water fall freely off a vertical or near vertical face as in an ordinary overfall (free-fall) spillway. Statement (I) restates this definition correctly, so (I) is correct.
Step 2: Now examine statement (II), which compares chutes with a series of drop structures on steep terrain. A chute spillway is essentially one continuous lined channel, so it needs only one set of energy dissipation works, typically a stilling basin at the toe. A series of drop structures instead needs a separate structure, foundation and stilling arrangement at every drop, which multiplies construction and maintenance cost on a steep slope. So chutes genuinely work out more economical in that situation, making (II) correct as well.
Step 3: Since both the physical description in (I) and the economic comparison in (II) match accepted hydraulic structures theory, both statements are correct together, matching option 1.