The Parts of an Aqueduct
Aqueducts have been used over the centuries to carry water to places without a bountiful water supply. The most famous aqueducts are those of Rome. Using principles of engineering, Romans were able to build structures that efficiently transported water to all corners of their empire. Some of these aqueducts are still used in modern times. The structure of the aqueducts will be explored in this article.
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History
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The earliest record of an aqueduct dates back to 691 B.C. in Assyria, and Greece has records of simple aqueducts being built as early as 530 B.C. The first Roman aqueduct, Aqua Apia, was built in 312 B.C. It was the first of a total of 11 major aqueducts built over 500 years ago that would eventually supply the city of Rome. At the height of the city's population when it numbered over one million people the aqueducts were able to deliver up to one cubic meter of water per person. This is more than what most modern cities can supply.
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Facts
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Channels and tunnels were the largest component of an aqueduct. The majority the conduits ran underground to avoid potential saboteurs. In fact, four out of every five miles of aqueduct were underground. Vertical shafts were dug at intervals to provide access and ventilation to the conduits. Closed pipes were occasionally used to cross valleys, using the inverted siphon method in which water pressure forced the water to flow down and back up and out to the channels. When the use of pipes were not an option for crossing a valley, arcades (bridges constructed of stone arches) were used to keep the aqueduct elevated, therefore, eliminating the need for pipes. The arcades carried the water from one side of a valley to the other.
Features
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Pipes were made from lead and the channels were lined with impermeable concrete when they ran through porous rock and arches. The concrete would form a waterproof lining that would not allow water to leak. Sedimentation tanks were built to slow down the water and let impurities settle at the bottom. In areas where two or more conduits ran near each other, stations were built where water could be exchanged between them to allow either an increase in flow for an aqueduct or the emptying of a conduit for maintenance and repair.
Functions
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When the water arrived at the Roman cities, it would flow into large tanks (castellum) that were situated above ground. The water would then run to an underground system of pipes. The pipes delivered the majority of the water to public fountains, baths, and/or drinking basins. The emperor and the very rich would have water piped to their homes as well.
Misconceptions
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The fall of the Roman Empire has been attributed, at least partially, to lead poisoning from the lead pipes that transported the water. However, this was unlikely due to two factors. First, the water in the aqueducts was almost always flowing. This did not allow water to sit for long periods needed for lead contamination. Second, the water used by Romans was hard water carrying dissolved minerals. The minerals would form a coating on the pipes acting as a buffer between the lead and the water.
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References
Resources
- Photo Credit "Aqua Ducks" is Copyrighted by Flickr user: jurvetson (Steve Jurvetson) under the Creative Commons Attribution license.
