Pressure conduits and conveyance works: Which statement below is INCORRECT in general water-supply practice?

Introduction / Context:
Water-conveyance systems include pressure pipes, tunnels, and aqueducts. Section shapes and hydraulic controls differ depending on whether the flow is pressurized or open-channel. This question distinguishes typical practice from an incorrect generalization.

Given Data / Assumptions:

• Pressure pipes convey under head; alignment is not constrained by HGL grade.
• Tunnels may carry either open-channel or pressurized flow; circular shapes are common for pressure and structural reasons.
• Aqueducts in water-supply/irrigation typically operate as open channels (rectangular/trapezoidal), not circular.

Concept / Approach:
Separate pressure systems from open-channel carriers. Circular is excellent for pressure (isotropic hoop strength), but open-channel aqueducts use noncircular prismatic sections that optimize free-surface flow, construction, and maintenance.

Step-by-Step Solution:

Verification / Alternative check:
Design manuals illustrate aqueduct flumes as rectangular/trapezoidal concrete channels; pressure tunnels and steel liners are often circular for structural efficiency.

Why Other Options Are Wrong:
Options (a) and (b) reflect accepted practice; “None/All” are distractors because (c) is demonstrably inaccurate as a blanket statement.

Common Pitfalls:
Confusing pressure conduits with open channels; assuming circular sections are universal regardless of flow regime.

Final Answer:
Aqueducts (open-channel carriers) and tunnels are generally kept circular in section.