Aqueduct

AQUEDUCT (from the Latin aqua — water and ductus — conveyance), a bridge structure serving to pass water or another liquid through flumes and pipes. Aqueducts are constructed when water supply lines cross rivers, deep valleys, streets, roads, and the like, and are built of stone, concrete, or iron. Aqueducts with flumes were widespread in ancient Roman gravity-fed water systems and are currently constructed for gravity water conduits supplying water from a water source to pressure reservoirs or to water-lifting stations. Similar devices are found on the water supply systems of Vienna, Paris, near New York (the Croton Aqueduct), and others, as well as for irrigation and other canals when crossing rivers and valleys. Aqueducts with flumes for water supply systems are built enclosed and are ventilated. When a water supply or sewage pipe is laid inside an aqueduct, it must be thermally insulated to protect the liquid from freezing and overheating.

Aqueducts for pipes are advisable to build in cases where laying pipes under a riverbed is unreliable, for example, due to instability of the river bottom and bed, or when the construction of an aqueduct is cheaper than other devices. An example of an aqueduct with a pipe is the Rostokin Aqueduct of the Mytishchi water supply system of the Moscow water supply, where an old stone aqueduct, the so-called Catherine Gravity Water Conduit built in the 18th century, was utilized. This aqueduct crosses the Yauza River and its valley.