Canal–drainage intersection at the same level — name the cross-drainage work used when a canal and a natural drain meet at approximately the same bed level.

Introduction / Context:
Cross-drainage works (CDWs) enable canals to cross natural drains or rivers. The selection depends on the relative bed levels of canal and drain. This question targets recognition of the correct structure when both are at about the same level, a frequent planning and exam topic in irrigation engineering.

Given Data / Assumptions:

• One canal and one drainage channel (natural stream) intersect.
• Their beds are at roughly the same elevation (no significant vertical separation).
• We seek the proper CDW type for hydraulic and operational compatibility.

Concept / Approach:

Common CDWs: aqueduct (canal over drain), super-passage (drain over canal), siphon or siphon aqueduct (pressure flow), and level crossing (beds at similar level). When levels match closely, water exchange and regulators are provided so that each can pass its design flow without undue interference—this is the level crossing arrangement.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

If canal bed is much higher → aqueduct/siphon aqueduct. If drain bed is much higher → super-passage. Equal levels favor a level crossing.

Why Other Options Are Wrong:

“an aqueduct” — requires canal bed appreciably above the drain.

“a syphon (inverted siphon)” — used where pressure conduit is needed due to level differences.

“inlet and outlet (sluice pair)” — local appurtenances, not the cross-drainage structure type itself.

“a super-passage” — for drain above canal.

Common Pitfalls (misconceptions, mistakes):

Forgetting the relative-level criterion; confusing level crossing with aqueduct/super-passage terminology.

Final Answer:

a level crossing