aqueduct

n. manmade canal for carrying water flow

An aqueduct is an artificial channel that is constructed to convey water from one location to another. The word is derived from the Latin aqua, "water," and ducere, "to lead." The word is also used for any bridge that carries water, similar to viaducts, though they carry water instead of a road or railway. Sufficiently large aqueducts may also be usable by boats or ships. While a road bridge often carries the roadway at a more elevated level than the rest of the road, such a variation of height is not possible for an aqueduct.
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Aqueduct /aq·ue·duct/ any canal or passage. cerebral aqueduct a narrow channel in the midbrain connecting the third and fourth ventricles. [more]Aqueduct - Community and Resources

Noun
1. a conduit that resembles a bridge but carries water over a valley
(hypernym) conduit
(part-meronym) arch

(n.)
A conductor, conduit, or artificial channel for conveying water, especially one for supplying large cities with water.
  

(n.)
A canal or passage; as, the aqueduct of Sylvius, a channel connecting the third and fourth ventricles of the brain.