WATER SUPPLY SYSTEMS: CISTERNS, RESERVOIRS, AQUEDUCTS
Historically, communities have relied on tapping and preserving natural sources
for their water needs. Supplying great quantities of water, crashing and cascading
down into copious basins of city fountains, such as the famous Treni Fountain
in Rome, was a luxury few communities and states could afford before the Roman
era (A47). Saving rainwater in rooftop reservoirs and cisterns was the
most common method of providing water for communities which did not enjoy an
adequate or safe supply on site, such as a natural spring or a fresh water stream.
Before the more sophisticated, hygienic and convenient "running-water" supplies
made available by conduits and aqueducts were widely established, many Roman
cities were served by simple but effective cisterns and tanks.
In Pompeii, before the construction of the city's aqueduct at the end of the
1st century B.C., individual water tanks (impluvium) often located in the atrium
of a house, under the roof opening, provided the modest water needs of the household
(A46). Larger houses or villas, often depended on extensive cisterns.
Villa Jovis, emperor Tiberius' retreat high up on the rocky eastern end of the
water-starved island of Capri, was virtually designed around a courtyard supported
by a vast netweork of concrete, vaulted cisterns (A45, A44, A43).
In Cosa, a republican colony north of Rome, communal cisterns, such as the
one illustrated here, served whole neighborhoods (A42). The need to save
every drop of water was even more urgent in desert and semi-desert settlements.
Still, it is amazing that even such cities struggled to retain the typical Roman
cultural and recreational facilities, such as a high impact water user like
a public bath (A41). Tiddis, a small North African city perched on an
arid, clayey hillside in Algeria, near Constantine, boasted a fair sized public
cistern serving the city and its baths (A80, A79).
Often, the water capacity of public cisterns were supplemented by aqueducts,
or a special line from an aqueduct. Cisterns could become the terminus of an
ordinary aqueduct. One of the most impressive and immense cisterns ever created
in the Roman world is near Pozzuoli, in the bay of Naples (A77, A78).
Known locally as "Piscina Mirabile," this gigantic structure has over fifty
square bays of tall, soaring vaults. Although not intended to be experienced,
it is a dramatic space. The construction of such cisterns could not have been
possible without advanced concrete technology. (A76) All things being
equal, the constant fresh supply of water brought by an aqueduct was prefered
over a reservoir supply. Early in their history Romans developed a highly effective
systems of bringing water in conduits to their cities from sources many miles
away. The conduits were either open channels, or more commonly, pipes made of
clay or bronze or lead, laid underground. The system relied predominantly on
gravity, the water source had to be higher than the city served by it. The familiar
image of the Roman aqueducts as mighty rows of arches carrying conduits, was
only true to cross low plains, valleys, and river beds. Impressive as these
are, they constituted only a small portion of a water-line which could be 30-40
miles long. Romans were well justified to be proud of their aqueducts, a useful
undertaking serving the multitude rather than, in a real, functional way, rather
than, as they saw it, the beautiful but useless monuments of Greece, or the
massive but idle pyramids of Egypt (Frontinus, Aqueducts 16). Even though the
far greater length of an aqueduct would have been an unassuming underground
pipeline, the spectacular remains of this network stretching across the remotest
corners of the vast empire on tall, majestic arches tell an important part of
the story of Roman building technology and urbanization that the more popular
accounts of Roman military and political prowess do not.
Rome's first aqueduct, Aqua Appia, dates back to 312 B.C. By the beginning
of the 2nd century A.D., the capital was served by nine aqueducts supplying
a total of one-million cubic meters of water daily. Once water was brought into
the city it was piped to different neighborhoods from special distribution tanks
(castella). Imperial establishments, baths and public fountains received priority
over private uses. One can still see many examples of well-preserved public
fountains in the streets and squares of Pompeii and Herculaneum (A75, A74,
A73, A72).
The double-arched gate known as Porta Maggiore in Rome carries two aqueducts,
the Aqua Claudia and Aqua Novus, over two major roads (Via Labicana and Via
Praenestina), c. AD 41-54 (A71, A70). Superimposing, or 'piggybacking,'
two conduits over one another is ingenious, and makes good engineering sense.
The gate itself, reminiscent of a triumphal arch, is simply a special, architectural,
treatment of a stretch of these two aqueducts. It is distinguished by three
decorative pedimented aediculae whose traditional columnar orders display a
highly mannered application of masonry rustication.
[A71] |
[A70] |
(A69, A68, A67) One of the best preserved, textbook, examples of a Roman
aqueduct is the Pont du Gard, built by Augustus' friend Agrippa, ca. 20 B.C..
This aqueduct brought water to Nimes in southern France (ancient Nemassus) from
a source 30 miles away. The three-tiered arches of the structure cross the valley
of River Gardon at a height of 150-feet. Water ran at a slope of 1:3000 in an
open conduit on the uppermost level (A66). Like a number of other, this
aqueduct served also as a bridge over the river valley; a road was carried by
the lower arches. The simple rhythm of unornamented stone piers and arches (whose
spans varied), display a sense of power and elegance, befitting a structure
of pure utilitarian concern.
Thanks to the generosity of one of its wealthy citizens, C. Sextius Pollio,
Ephesus, the metropolitan city of Roman Asia Minor, received its first aqueduct
about the same time as Nimes, making the city ready and able to support the
half-dozen or so major baths it was to built in the next two or three centuries
(A65, A64). The classically composed, but austere arches are constructed
in finely dressed stone typical of much Roman construction in Asia Minor. The
span of the second-story arches are exactly one-half of those of the first story,
every other upper story pier resting precisely midpoint over the keystone of
the large arch below (A63). The Ephesian aqueduct is admittedly less
grand than the Pont du Gard, but in the words of the late John B. Ward-Perkins,
"it is no less symbolic of the solid material benefits of the new [Augustan]
regime."
[A65] |
[A64] |
[A63] |
[A62] |
[A61] |
In the wealthy, imperial decades of Pax Romana, few cities, however remote
or provincial, could not boast of an effective and healthy water supply system.
We have chosen three from Asia Minor, Alinda in Caria (A62, A61), Antioch-in-Pisidia
(A100, A99, A98), and Anazarbos in Cilicia (A97, A96) to illustrate
the heroic proportions of this undertaking. No doubt local materials and building
traditions determined the design and structure of these functional monuments,
the former two constructed in heavy, rusticated blocks of ashlar; the last uses
a more economical construction closer to Roman concrete. In Anazarbos, the aqueduct
is constructed of a mortared rubble core throughout, faced with sturdy ashlar
piers and small, squared blocks above.
[A100] |
[A99] |
[A98] |
[A97] |
[A96] |
All of the aqueducts reviewed above are examples of the open gravitational
system where water is carried in an open conduit (the channel was normally covered
by plaques of stone to keep water clean but unsealed), down grade from the source.
In the 3rd-century aqueduct which supplied the hill-top city Aspendos in Pamphylia
(in southern Turkey), water was brought from a high mountain source under pressure
in closed and sealed stone pipeline (A95, A94). In order to relieve the
excessive pressures built up in such a closed system (technically a siphon),
three "pressure towers" were incorporated into the 850-meter stretch of the
aqueduct arcade (A93). The study of the mixed construction of these well-preserved
towers -- a composite of rusticated stone blocks, brick and brick-with-relieving-arches,
and rubble facing over mortared rubble -- is instructive of the kind of structural
eclecticism Roman engineers were capable of producing in order to employ the
most effective "cost-efficient" system.
[A95] |
[A94] |
[A93] |
[A91] |
[A92] |
(A91, A92) The famous city of Carhage in Numidia (modern Tunisia) was
supplied by an aqueduct which brought water from the hilly hinderland to the
south . Long stretches of this aqueduct was almost entirely supported by tall
arches constructed in ashlar covered mortared rubble. It terminated in an impressive
cistern elevated as a decorative terrrace on the rising slope of Mount Zaghouan
(A90, A89, A88). The cistern was not simply a functional water tank,
but an elegant nymphaeum, a sanctuary dedicated to the Nymphs -- female deities
protecting natural springs and water sources. The cistern/terrace is surrounded
by a horse-shoe shaped colonnade, the center of which is a grotto pavilion leading
to the water source. At the bottom of the terrace, flanked by monumental stairs,
is a double-oval decorative pool (A87, A86). The progress of water from
the heights of its rocky mountain, down to the busy port city, appears to have
been visually documented and celebrated.
[A90] |
[A89] |
[A88] |
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[A86] |
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