Aqueduct cross-sections in irrigation/water conveyance: Which of the following cross-sectional shapes are commonly designed for aqueducts?

Introduction / Context:
Aqueducts convey water over obstacles such as valleys and roads. The selection of cross-section depends on hydraulics, structural economy, freeboard, and constructability. Several shapes are standard in practice.

Given Data / Assumptions:

• Reinforced concrete aqueducts in open channel or pressure flow.
• Hydraulic performance and structural formwork considerations.

Concept / Approach:

Circular, rectangular, and horse-shoe sections are all used. Circular sections are efficient in pressure flow, rectangular sections suit open channels and easier formwork, and horse-shoe sections balance structural arching with hydraulic efficiency, often used in tunnels and large conduits.

Step-by-Step Solution:

Verification / Alternative check:

Case studies and standard drawings in irrigation departments show all three shapes in service depending on site conditions.

Why Other Options Are Wrong:

• Single-shape options ignore the diversity of typical designs.
• “Triangular only” is not a standard aqueduct section.

Common Pitfalls:

• Confusing open-channel aqueduct sections with closed pressure mains.
• Neglecting freeboard and air-entrainment in high-velocity open channels.

Final Answer:

all the above.