Potaissa (Romania)

Roman aqueducts: Potaissa (Romania) Turda - POTAISSA
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The aqueducts of Potaissa

Florin Fodorean, Cluj-Napoca, Romania

The Roman water supply system was so carefully designed and maintained that even today we are astonished at these structures (1). The engineer's achievements in this domain were so outstanding that Plinius or Vitruvius didn't hesitate to admire the aqueducts and to write about them. Even after a long period of time, the work of engineers and architects in the modern era has been inspired by the Roman achievements.
The settlements of Roman Dacia were, of course, part of this program. At Ulpia Traiana Sarmizegetusa, Apujum, Romuia, Ampelum, and Drobeta, archaeological discoveries and inscriptions provide us with important information about the water supply system. An elevated aqueduct from Dacia is attested at Porolissum. Traces of other water pipes and aqueducts are present in at least 86 settlements and 21 military camps in Dacia (2).
With an estimated population of 20,000 inhabitants, including the legion V Macedonic, Potaissa benefited from two aqueducts: one for the city and another for the military camp (castrum).


Two aqueducts from the Caput Aquae to the city of Turda (ancient Potaissa)

1. The spring, position, and physical landscape

The spring chosen by the Romans can be located today in the point called "Izvorul Copăcenilor". It lies south-west from Copăceni, at the northern limit of the Trascăului Mountains, on the right side of the current road Turda - Petreşti. From this point to the military camp the distance is around 5,000 m, following the line of the hills. This line begins at the altitude of 525 m at the caput aquae (spring) and it ends at 375 m altitude, on the hill where the Roman military camp was built.
Starting from the same point, another aqueduct was built for the city. Its route is orientated, in the first part, to north-east, until it reaches the Racilor rivulet. Further on, the aqueduct follows the course of this rivulet, heading south-east to the Roman city.
Delimited at the north by the Racilor valley, the Trascău Mountains are represented close to Săndulesti by a narrow strip of jurassic limestone, extended in the peak of Sănd (759 m) (3). Drainage effects created an interesting, particular landscape here. The Racilor valley forms the gorge of Tureni here. The water from this spring has superior qualities and properties which make it good, even nowadays. The discovery and use of such springs in Roman period are described by Vitruvius (4);.

2. The aqueducts of Potaissa in the modern historiography

In 1810 Moise Nicoară noticed at Copăceni the traces of the aqueduct. The indication regarding the spring is extremely general: "l climbed up close by the channel, on a hill" (5). Few years later, M. J. Ackner and J. F. Neigebaur mentioned the traces of the same aqueduct (6).
At the end of the XIXth century, Orbán Balázs presented the antiquities from Turda in a book (7). In a subchapter about aqueducts, he remarks on the position of the spring, the qualities of the water, the approximate route of the aqueduct and the possible existence of an aqueduct for the Roman camp placed on Zânelor Hill: "From here, at a distance of one mile from the hill above Copăceni, close by the road which goes to the mountain ("Drumul Mocanilor"), there is a corridor of stone, where a rich spring called Şipotul (Cişmeaua) de Piatră (Kőcsorgó) can be found, with a rivulet of water as thick as an arm and as cold as ice, which flows in a sort of stone basin. The Romans collected the water from the beginning. They draw it from its riverbed, forcing it to enter in the pipes of the aqueduct and guiding it to the Roman camp and the city of Potaissa".
Interesting information and drawings about the aqueducts are present in the recently published notices of I. Téglás (8). The presentation of the archaeological discoveries at Sănduleşti begins with a geographical description of the region. There are several drawings of the limestone massif in the place called Vágottkő, close to the spring.

3. The aqueduct for the Roman military camp

The physical landscape, route, technical details and hydraulic works. At 70 m south-west of the road from Turda to Petreşti and 40 m south of the road to Sănduleşti, in the autumn of 2007, during the excavation of a trench for a gas pipe, fragments of the aqueduct which supplied the Roman military camp were discovered at a depth of -0,80 m. Two years earlier, in the winter of 2005-2006, when the works for the construction of the highway Braşov-Borş started, another water pipe was discovered, at the same depth, almost at the same place as the other one, at 130 m north-east of the highway and 30 m south to the road to Sănduleşti (9). The pipe was found in one piece: 0.60 m in length, external diameter 0.165 m, internal diameter 0.125 m. Three decades ago, in 1978, west of the military camp and close to the porta decumana, other pipes from the same aqueduct were discovered (10). These were identical in diameter, only the lengths were different (0.43 m, 0.55 m).
The same aqueduct was identified in the gardens on the western side of the village Copăceni (11). This point is situated south of the current road between Petreşti and Turda, on the right hand side of it (keeping the same direction mentioned above). To sum up, these recent archaeological discoveries combined with older information allow us to establish the route of this aqueduct. It starts from Izvorul Copăcenilor (525 m) and, after 500 m, it passes on the right hand side of the road between Petreşti and Turda (520 m), keeping the same (south-east) direction. It was discovered at two points, close to the road to Săndulesti (453 m). Further on, following the same direction, it ends at the Roman military camp (375 m) (12).

The length of the aqueduct is around 5 kilometers and the height difference is 150 m, meaning 30 m at every 1000 m, so the overall slope of the channel was 3%. According to these values and the internal diameter of the pipes (0.125 m), the aqueduct could have had a maximum discharge of 15 liters/second (0.015 m3/sec.). This means 54,000 liters of water per hour and 1,296,000 liters a day (1296 m3/d). It means that every soldier could have benefited daily of around 216 liters of water. But, of course, the major quantity of water was used for the thermal buildings situated in the praetentura dextra.
There is, however, a problem in understanding how the Roman engineers maintained a constant flow rate under such conditions, with such a slope. In recent studies (13) Hubert Chanson shows that, in order to understand these aspects, one should know the ancient flow rates, which is extremely difficult. In the case of Potaissa, we can assume, based on other examples, that close to the spring the Roman engineers built a stone basin (caput aquae), which collected the water of the spring. In order to ensure a constant flow rate for the aqueduct, they could use a simple solution by providing this basin with an overflow and determine its position for a flow rate of 15 l/sec.
The aqueduct has a total length of 5,000 m and a pipe has 0.50 m in length. So, basic calculations show that at least 10,000 ceramic pipes were necessary to complete the aqueduct. We suppose that it was built by the soldiers from legio V Macedonica after their arrival at Potaissa, in AD 168.

4. The aqueduct for the city

Physical landscape, route, technical details and hydraulic works. Starting from the same point, Izvorul Copăcenilor, another aqueduct supplied the city of Potaissa with water. Its traces were discovered several times, beginning in the XIXth century, by I. Téglás in the gardens of inhabitants of Copăceni, at the western side of the village.
In 1977-1978 professor Mihai Bărbulescu and Dorin Urşut made investigations on the right side of the valley of Copăceni, beginning from the old mill situated in the north-western part of the village, to the former farm from Turda Nouă. Over a distance of 2.1 kilometers they identified the aqueduct at five points.
The traces of the aqueduct disappear at the entrance to the modern city of Turda. In 1986 Gh. Lazarovici identified the aqueduct over a distance of 7-8 m, at a point situated 600 m west of the entrance in Turda. The pipes were 0.39 m in length, the walls 0.38 m thick, and 0.255 m internal diameter.

So, between the old mill from Copăceni to the entrance in the Roman city the aqueduct had a length of almost 4,000 m. The height difference is 36 m (386 m - the old mill, 350 m at the city of Turda). So there is a slope of 9 m at every kilometer (less than 1%), almost in accordance with the figures provided by the Romans (Vitruvius recommended a slope of 5 m at every kilometer and Palladius 9,7 m) (14).


A detailed drawing of one of the stilling basins (SB) found in a garden in Copaceni. In order to overcome a height difference between the spring and the remaining course of the civil aqueduct at the old mill of Copaceni and beyond, the Romans installed a series of stilling basins to dampen the water energy. The height difference was 139 m over a distance of 1250 m resulting in a fall of 11% (!) where traditionally a slope of less than 1% was common.
The first part of the route of this aqueduct illustrates at the highest level, once again, the engineering design techniques and hydraulic expertise of the Roman engineers. Between the spring (525 m) and the old mill (386 m) positioned on the right bank of the Racilor valley, there is a distance of 1250 m and a height difference of 139 m. This represents a steep slope of 7%. The solution chosen by the Roman engineers was very efficient: they used stilling basins to dampen the water energy and to change the direction of the aqueduct. Such a basin was discovered in Copăceni, in the garden with no. 492. We have studied this monument recently.
This stilling basin was mentioned at the beginning of the XXth century by I. Téglás. He made a drawing (see below) and noted the dimensions: 0.79 m length, 0.75 m width, 0.46 m depth, the walls were 0.11 m thick. From the drawing and the description, we are able to conclude that the basin had two orifices: one on the left side with a diameter of 0.15 m, positioned at the bottom, and the other one on the frontage, with a diameter of 0.20 m, positioned roughly in the middle of the front side of the basin. Then he noted that it was brought there, at Copaceni, from the spring, together with fragments of ceramic pipes (15). In another article published in 1896 the same Téglas mentioned that close to a spring he identified a Roman basin (16).
For the first time after these observations, a stilling basin was identified in 1996 in Copăceni by Dorin Ursuţ (17). After we saw this device ourselves, we managed to outline its exact dimensions, which correspond with those indicated by Téglás: 0.80 m in length; 0.76 m in width and 0.42 m in height. On the inside, the dimensions are 0.55 x 0.55 x 0.30 m. So its capacity is 0.09 m3 (90 liters). The orifice on the left side, with a diameter of 0.15 m, is positioned at the bottom of the basin, close to the corner. This is the point where the water entered the basin. On the front side there is the other orifice, with a diameter of 0.25 m inside and almost 0.20 m on the outside. The basin has a convex bottom. It reaches the maximum convexity of 0.11 m in the central part. The basin was built in this way in order to be positioned firmly on the terrain. It was covered by a block of stone and was positioned below the natural ground level, by at least -0.80 m. By design, this basin had a double function: to dampen the water energy and to change the direction of the aqueduct. The water entered in the basin and made a circulatory movement inside of it, so the flow rate could be controlled. After that, it left the basin into the ceramic pipes. We suppose that the basin identified in 1996 should be identical to that drawn by Téglás in 1900. Such stilling basins were placed on the whole section with the steep slope, to assure a constant flow rate.
The average length of one ceramic pipe is 0.39 m. The total length of the aqueduct is almost 5000 m. So, at least 12,800 pipes were used to complete the aqueduct. It is difficult to tell when this aqueduct was built. Potaissa developed rapidly after the arrival of the legion. It is possible that this aqueduct was built during the same period as the one for the military camp.

Assuming a 0.25 m internal diameter pipe, calculations show a maximum flow rate of about 50 liters / second. This means 180,000 liters per hour and 4,320,000 liters in a day for a population estimated at 15,000 inhabitants. The result is a maximum of 288 liters for every citizen of Potaissa per day.

The aqueduct of the city, on its first part, was provided, as we saw, with stilling basins. In a recent article, Leveau explains the aspects regarding the aqueducts with steep sections (18). His example is suggestive. In Gaul, two of the four aqueducts of Lugdunum, those from Yzeron and Brévenne, have been built in difficult landscapes. At Yzeron, a section of the aqueduct had a height difference of 80 m over 1 kilometer. Here two dropshafts were discovered, with a distance of 490 m between them, and a height difference of 38 m. By creating such hydraulic structures, the Romans succeeded reducing the slope to a normal value: 1 m for 1 kilometer. In the case of Potaissa, as we saw, for a sector of 1250 m of the aqueduct with a height difference of 139 m, the Roman used stilling basins to dampen the water energy.

5. The distribution of water at Potaissa. Other discoveries

It is difficult to clarify, today, how the Romans distributed the water in the city of Potaissa. Several discoveries of pipes show, though, that a pipe system was used. All these discoveries are concentrated in the Roman city, in a zone with many traces of buildings. Along the valley of Sănduleşti, which separates the hill called "Cetate" from the other one called "Zânelor", Téglás noticed and drew a stone block (0.70 x 0.65 x 0.35 m), with an orifice in the middle with the diameter of 0.40 m (see photo below). He noticed that it belonged to an aqueduct. Ceramic pipes were discovered on Bălcescu Street, south-east from Cetate hill. A water pipe was identified on Cheii Street, in 1964, when the road to Aiud was constructed. The ceramic pipes have a length of 0.265 m and a diameter of 0.10 m.
In the point called Furdulăşeni ("Forduló-mál"), close to the south-eastern corner of the Roman military camp, another water pipe is known to exist. Traces of another water pipe were found in Piaţa Romana, close to the former beer factory. In 1952-1953 other ceramic pipes were discovered when the construction of the General School no. 3 began. The pipes have 0.405 m in length and a diameter of 0.10 m. It is possible that this aqueduct was in function along the Pardei valley (19).

6. Conclusions

Recent archaeological discoveries, combined with former Information and data, allow us to create an image about the Roman water supply system of the military camp and the city of Potaissa. Two aqueducts were constructed: one for the military camp, with a maximum discharge of 15 liters/sec, and another one for the city, with a maximum discharge of 50 liters/sec. The spring provided a significant quantity of water for the camp and the city: around 5,600,000 liters of water every day (5,600 m3/d).

dr. Florin Fodorean, Cluj-Napoca, Romania

Notes

  1. On this topic we mention some contributions:
  2. G. BĂEŞTEAN, Aprovizionarea cu apă în Dacia romană, Cluj-Napoca, 2007, p. 89-144.
  3. Gr. P. POP, Judeţul Cluj, Bucureşti, 2007, p. 45.
  4. VITRUVIUS, Despre arhitectură, Bucureşti, 1964, book VIII, Despre ape, p. 337-338.
  5. M. BăRBULESCU, Evoluţia cercetărilor privind Potaissa romană, in Potaissa. Studii şi comunicări, 2,1980, p. 285, note 17.
  6. M. BĂRBULESCU, Potaissa. Studiu monografie, Turda, 1994, p. 68.
  7. O. BALÁZS, Torda város és környéke, Budapest, 1889, ch. XI: Apeducte romane în Turda, p. 51-53 (we used the manuscript of the Romanian translation, kept at the Museum of Turda).
  8. I. BAJUSZ, Téglás István jegyzetei. Régészeti feljegyzések. l/1. Kötet, Kolozsvár, 2005, s.v. Szind - Sânduleşti, p. 348, 350-352.
  9. We wish to thank Prof. Mihai Bărbulescu for helping us in understanding better the archaeological information and the modern sources. We wish to thank our colleagues Lect. Ph.D. Sorin Nemeti from the University ″Babes-Bolyai″ Cluj-Napoca and Ph.D. Mariana Pîslaru from the Museum of Turda for all the information and the materials concerning the aqueduct.
  10. M. BĂRBULESCU, Potaissa [n. 6], p. 68.
  11. Repertoriul arheologíc al judeţului Cluj, Cluj-Napoca, 1992, p. 159, s.v. Copăceni; F. FODOREAN, Drumurile din Dacia romană, Cluj-Napoca, 2006, p. 332.
  12. We made measurements on the terrain on February 29, 2008.
  13. H. CHANSON, The Hydraulics of Roman Aqueducts: What do we know? Why should we learn? in Proc. World Environmental and Water Resources Congress, ASCE-EWRI Education, Research and History Symposium, Hawaii, USA, Keynote lecture, 13-16 May, 16 pages.
  14. Ph. LEVEAU, La construction des aqueducs, in Dossiers de l'archéologie: Aqueducs romains, nr. 38, oct.-nov. 1979, p. 12.
  15. I. BAJUSZ, Téglás István jegyzetei, [n. 8], p. 377; Repertoriul arheologic al judeţului Cluj, 1992, p. 161, s.v. Copăceni; M. BĂRBULESCU, Potaissa [n. 6], p. 68.
  16. I. TÉGLÁS, Torda - Aranyosmegyei régiségekről, în Archaeologiai Ertesitõ, XVI, 1896, p. 427-428.
  17. D. URSUŢ, A. CZIFRA, F. FODOREAN, Căminul roman de apă pentru ruperea presiunii de la Copăceni (jud. Cluj), in ActaMP, XXV, 2003, p. 145-148.
  18. P. LEVEAU, L'archéologie des aqueducs romains ou les aqueducs romains entre projet et usage, in Elementos de Ingenería Romana. Congreso europeo Las Obras Públicas Romanas, Tarragona, 3-6 noviembre 2004, p. 111.
  19. M. BĂRBULESCU, Potaissa [n. 6], p. 72-80.

Romania and the Tabula Peutingeriana

The Tabula Peutingeriana (Peutinger map) is an itinerarium depicting the road network in the Roman Empire. The original map is lost, an unique copy was last revised in the fourth or early fifth century. It measures about 0,35 m in height and 7 m in length. Dr. W. Bruijnesteijn van Coppenraet made this outline (from: De Romeinse reisgidsen, 2006). Distances in Roman miles (1482 m). Vignettes are Mansiones (official stopping place along a Roman road with (or without) some facilities).

Turda - POTAISSA

Item Info Mil Info Civil
Length 5,000 m 5,000 m
# Pipes 10,000 12,800
Internal diam 0.125 m 0.255 m
Volume 1,300 m3/day 4,300 m3/day
Gradient 3 % 0.9 %
Period 2nd half 2nd c 2nd half 2nd c
Features
  • series of stilling basins
On the map Present name Distance
Porolissum Moigrad-Jad 4
Certiae Romita 17
Largiana Romănaşi 15
Optatiana Sutoru 16
Napoca Cluj - Napoca 24
Potaissa Turda 12
Salinae Ocna Mureş 12
Brucla Aiud 12
Apulum Alba Iulia 8 / 15
Blandiana Vinţu de Jos (8)
Acidava Doştat (15)


Recommended literature : F. Fodorean: The aqueducts of Potaissa (in: SRdFG vol 28 (2011) pag 95 - 108
Recommended websites   : none
How to visit                  : see above
HOME More literature on more aqueducts Last modified: March, 2012 - (webmaster)


Dacia county
Two aqueduct courses
Elevation map
Area of the spring

Panoramic view
Near the caput aquae
Details of the spring area
Scenic view

Ancient stone quarry
Two ceramic pipes
Pipes in situ
Castrum Legio V

View from Copaceni
Pipes of different sizes
Stilling basin
Interesting basin

Details of the basin
Drawing plus Photo
Detailed drawing