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Roman aqueduct
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Romans constructed numerous aqueducts (Latin aquaeductus, sing. aquaeductus) to supply water to cities and industrial sites. These aqueducts were amongst the greatest engineering feats of the ancient world, and set a standard not equaled for over a thousand years after the fall of Rome.
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Romans constructed numerous aqueducts (Latin aquaeductus, sing. aquaeductus) to supply water to cities and industrial sites. These aqueducts were amongst the greatest engineering feats of the ancient world, and set a standard not equaled for over a thousand years after the fall of Rome. Many cities still maintain and use the ancient aqueducts even today, although open channels have usually been replaced by pipes.
The Romans typically built numerous aqueducts to serve any large city in their empire, as well as many small towns and industrial sites. The city of Rome itself, being the largest city, had the largest concentration of aqueducts, with water being supplied by eleven aqueducts constructed over a period of 500 years. Scholars can even predict the size of the city by its water supply. They served potable water and supplied the numerous baths and fountains in the city, as well as finally being emptied into the sewers, where they performed their last function in removing waste matter. The methods of construction are well described by Vitruvius in his work De Architectura written in the first century BC. His book would have been of great assistance to Frontinus, a general who was appointed in the late first century AD to administer the many aqueducts of Rome. He discovered a discrepancy between the intake and supply of water caused by illegal pipes inserted into the channels to divert the water, and reported on his efforts to improve and regulate the system to the emperor Nerva at the end of the first century AD. The report of his investigation is known as De aquaeductu.
In addition to masonry aqueducts, the Romans built many more leats — channels excavated in the ground, usually with a clay lining. They could serve industrial sites such as gold mines, lead and tin mines, forges, water-mills and baths or thermae. Leats were very much cheaper than the masonry design, but all aqueducts required good surveying to ensure a regular and smooth flow of water.
Construction of Roman aqueducts
The aqueducts required very careful planning before building, especially to determine the water source to be used, the length of aqueduct needed and its size. Great skill was needed to ensure a regular grade, so that the water would flow smoothly from its source without the flow damaging the walls of the channel. As the need for water grew, extra sources would be utilised, very often making use of existing structures as with the Aqua Claudia and Anio Novus in Rome. The problems of aqueduct building and use are described by Vitruvius and Frontinus, the latter producing a long report on the state of the Aqueducts of Rome in the last years of the first century AD.
Several surveying tools were used in the construction of Roman aqueducts, one example being the chorobates. The chorobates was used to level terrain before construction. It was a wooden frame supported by four legs with a flat board fitted with a water level. Another tool used in the construction of the aqueduct was the groma. Gromas were used to measure right angles. A groma consisted of stones hanging off four sticks perpendicular to one another. The instrument which is the forerunner of the theodolite was known as the dioptra, and was used to measure vertical angles.
Industrial aqueducts
Many aqueducts were built to supply water to industrial sites, such as gold mines, where the water was used to prospect for ore by hydraulic mining, and then crush and wash the ore to extract the gold. They usually consisted of an open channel dug into the ground, with a clay lining to prevent excessive loss of water and sometimes with wooden shuttering. They are often known as leats. However, they were built just as carefully as the masonry structures, but often at a higher gradient so as to deliver the greater volumes needed for mining operations. The large quantities of water supplied by the aqueducts were used for prospecting for ore-bodies by stripping away the overburden, and for working the ores in a method known as hushing. The technique was used in combination with fire-setting, which involved creating fires against the hard rock face to weaken the rock and so make removal much easier. These methods of mining survived into Medieval times until the widespread use of explosives. The water could also be used to wash ores, especially those of gold and tin, and probably to work simple machines such as ore-crushing hammers and water wheels.
The remains of such leats are visible today at sites like Dolaucothi in south-west Wales, and at Las Medulas in northwest Spain. These sites show multiple aqueducts, presumably because they were relatively short-lived and deteriorated rapidly. There are, for example, at least seven major leats at Las Medulas, and at least five at Dolaucothi feeding water from local rivers direct to the mine head. The palimpsest of such channels allows the mining sequence to be inferred.
Apparent Decline of Aqueducts
With the fall of the Roman Empire, although some of the aqueducts were deliberately cut by enemies, many more fell into disuse from the lack of an organized maintenance system. The decline of functioning aqueducts to deliver water had a large practical impact in reducing the population of the city of Rome from its high of over 1 million in ancient times to considerably less in the medieval era, reaching as low as 30,000. On the other hand, many others elsewhere in the empire continued in use, such as the aqueduct at Segovia in Spain, a construction which shows advances on the Pont du Gard by using fewer arches of greater height and so greater economy in its use of the raw materials. The skill in building aqueducts was not lost, especially of the smaller, more modest channels used to supply water wheels. Most such mills in Britain were developed in the medieval period for bread production, and used similar methods as that developed by the Romans with leats tapping local rivers and streams. The massive masonry aqueducts and the many other visible remains, such as the Pantheon, Coliseum, and Baths of Diocletian, were to inspire architects and engineers of the Renaissance.
Lists of Roman Aqueducts
See also
External links
- Sextus Julius Frontinus, (On the water management of the city of Rome), translated by R. H. Rodgers. University of Vermont, 2003.
- - sophisticated maps and images.
- - entry on Roman waterworks.
- - with 25 descriptions in detail.
- - NOVA outline.
- - "Myths, Fables, Realities. A Hydraulician's perspective".
- - A dozen freely available published research articles on Roman aqueduct hydraulics and culvert design, and related topics by Professor Hubert Chanson, Department of Civil Engineering, The University of Queensland.
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