Cross-drainage works in canals: The structure provided to carry drainage water under a canal by pressure flow through an inverted siphon is termed as which of the following?

Introduction / Context:
When canals intersect natural drains or streams, cross-drainage works are used to pass one over or under the other. The nomenclature depends on which watercourse goes over/under and whether the flow is open-channel or under pressure.

Given Data / Assumptions:

• Drainage water passes below the canal via an inverted siphon (pressure flow).
• Canal maintains its level over the crossing.

Concept / Approach:
If the drainage passes under the canal with pressure flow (through an inverted siphon barrel), the structure is called a syphon aqueduct. If the drainage passed under the canal in free-surface flow, it would be a super passage. If the canal passed over the drainage (canal in a trough) with free-surface flow, it would be an aqueduct or super-aqueduct depending on relative bed levels.

Step-by-Step Solution:
Identify which stream is above (canal) and which is below (drainage).Check the flow regime below (pressure flow via inverted siphon).Select the correct term: syphon aqueduct.

Verification / Alternative check:
Hydraulic design manuals clearly define these four types with schematic sections showing water levels and conduit type.

Why Other Options Are Wrong:

• Syphon: generic; not specific to canal–drain crossing.
• Super passage: drainage passes freely under the canal without pressure flow.
• Aqueduct / super-aqueduct: canal over drainage with canal in open-channel flow.

Common Pitfalls:
Confusing which stream is on top; ignoring whether the lower flow is pressurized or free surface.

Final Answer:
Syphon aqueduct