Aqueducts were used to transport water from the source to the locations where the water was needed, either for irrigation or for urban water supplies. Roman aqueducts were built to promote quality of life and in general were built to serve existing urban centers, in many cases where prosperous life had existed for centuries before the aqueducts had been built. The Romans built aqueducts largely to supply baths and were an expression of civic pride. Many of the Roman inhabitants obtained their drinking water from wells prior to the construction of the aqueducts. The location and delivery point of the aqueducts were determined by geographical, economic, and social factors.
Roman aqueducts included many components including open channels and pipes. Figure 7.2 Shows an example aqueduct system and the downstream urban water distribution system. Obviously there are many system configurations that were built by the Romans, however, the drawing presents the major components including the siphon (inverted siphon) which was used in some systems. Various types of pipes constructed by the Romans included terracotta, lead, wood, and stone. Hodge (2002) provides an excellent discussion of the various types of pipes. Romans used three main types of conduits: (a) open channels (rivi per canales structiles), (b) lead pipes (fistuli plumbei) and (c) earthenware (terracotta) pipes (tubili fictiles). Open channels were built using masonry or were cut in the rock and flows were driven by gravity, while the lead pipes were used for pressurized conduits including inverted siphons.
Figure 7.2 Shows the components of an aqueduct system, starting with the source and ending with the distribution basin (castellum divorsium), then an urban water distribution system is shown. The many components included covered channels, storage and settling basins, aqueduct bridges, subterranean conduits, arcades of elevated channels. Some aqueducts also included inverted siphons which also included a header tank, a pressurized conduit, a venter bridge, and a receiving tank. Many aqueducts were built below the natural ground level, consisiting of long subterranean conduits. Secondary lines (vamus) were built at some locations along the aqueduct to supply additional water. Also subsidiary or branch lines (ramus) were used. At distribution points water was delivered through pipes (fistulae) made of tile or lead.
Fig. 7.2 Water supply system showing aqueduct and various components
Fahlbusch (2006) points out the following from examination of several aqueducts:
(a) size of the aqueduct canal was chosen according to the estimated discharge and the size varied along the course of the aqueduct;
(b) the cross-section was large enough for people to walk through the canal for repair and maintenance, particularly to remove calcareous deposits; and
(c) the cross-section was kept constant allowing manifold uses for encasings, especially the soffit scaffoldings for the vaults in a kind of industrialized construction.
There are many examples of Roman aqueducts that could be discussed. Figure 7.3 Shows a few examples of Roman aqueducts. One very interesting example (Fig. 7.3b) is the aqueduct of Nemausus (built around 20 B. C.) conveyed water approximately 50 km from Uzes to the castellum in the Roman city of Nemausus (present day Nimes, France). From an engineering viewpoint this aqueduct was a remarkable construction project. The elevation difference over the length of the aqueduct was only 17 m, with an average slope of 0.0008.5 m/m and the smallest
Fig. 7.3 Examples of Roman aqueducts (a) Aqueduct of Gorze near Metz, France. (b) Aqueduct of Nemausus just upstream of the Pont du Gard aqueduct bridge. (c) Aqueduct of the River Gier near Chaponost, France that supplied the Roman city of Lugdunum (Lyon, France). Color version available in Appendix. (d) Pena Cortada aqueduct near Chelva, Spain. Color version available in Appendix. (Copyright permission with L. W. Mays)
World History
