Historical and archaeological evidence shows that ancient Hellenes had developed underground aqueducts since the prehistoric times. However, innovative methods of underground aqueducts were developed in Hellas mainly during the Archaic, Classical, Hellenistic, and Roman periods. Since the well-known tunnel at the island of Samos, Hellas, was designed and begun its construction (ca. 550 bc) by Eupalinos of Megara (the first civil engineer in history), several underground tunnels (with and without well-like vertical shafts) were implemented in the country. The goal of Eupalinos tunnel was to transfer water into the town from a spring. This tunnel, representing the peak of ancient hydraulic technology, was dug through limestone by two separate teams advancing in a straight line from both sides of the mountain. Delivering fresh water to growing populations has been an ongoing problem since ancient times. Several underground aqueduct paradigms (e.g. Peisistration in Athens, Polyrrhenia in Crete), some of which are in use even today, are presented and discussed. After late Roman times and the Adrianic aqueduct a gap of about 1,700 years in construction of such hydraulic works is noted. However, a remarkable development of tunneling in Hellas appeared during the last 50 years due to the ‘cosmogony’ of the construction of infrastructure projects using modern technology, e.g. Evinos-Mornos aqueduct with 15 tunnels of 71 km total length and the diversion tunnels in Sykia to the Thessaly plain and Messochora of the Acheloos River of 17.5 and 7.5 km length, respectively. Also, very recently three small conventional tunnels and one tunnel boring machine (TBM) were constructed in Aposelemis aqueducts used for water supply of Iraklion and Agios Nikolaos cities in Crete. As a consequence, significant design and construction experiences were gained. Overall, it seems that underground aqueducts of modern societies are not very different in principle from those during antiquity.

INTRODUCTION

Management in drinking water supply has always been of fundamental importance for human kind from antiquity. Ancient populations in order to have the available water resources in their cities were obligated to make tremendous efforts concerning the planning, the construction, and the maintenance of long and complex aqueducts, many of them developed in underground construction for most of their length. Underground aqueducts (e.g. qanats, tunnels, various types of inclined galleries with and without shafts, or with inverted siphons) bring groundwater and/or surface water from an area usually mountainous to the lowlands, sometimes several kilometers away, from where water is used.

Aqueducts including underground structures were implemented in the ancient Hellenic world for over 5,500 years (De Feo et al. 2013). It should be noticed that no large-scale water lifting techniques were available, and water was transferred from the source (usually a spring) by aqueducts by gravity. For the semi-arid regions inhabited by the Hellenes during Prehistoric, Classical, and Hellenistic times, it was all too natural for every city to have its own water supply system as a basic feature of civilized life and development. Yet, because of the continuous wars between ancient Hellenic cities, aqueducts used to be hidden and subterranean rather than with visible conduits on bridges. The aqueduct system based on underground transport had been widely used by Hellenes and was reported as ancient already during Frontinius's time (ad 97), who was the commissioner of Rome's aqueduct. It had the advantage of protecting water from external impacts and pollution and at the same time was better maintained and preserved. An aqueduct of this type was composite. It was composed of tubes or channels, made of stone slabs or terracotta (Malacrino 2010).

The art of tunneling and the expertise in realizing deep shafts and underground canals to transport water since prehistoric times is suggested by the drainage works (drainage channels and polders) realized at Kopais basin (in Viotia, central Hellas) at the beginning of the 2nd millennium bc (Knauss 1991). The impressive remnants of this hydraulic work represent the most important land reclamation effort, including tunneling drains of Mycenaean Hellas (Koutsoyiannis & Angelakis 2004). To report for example the attempts of the Mycenaean civilization to cross the mountain ridge closing the basin with an artificial emissary discharging the water toward the sea, around the 12th century bc (Castellani & Dragoni 1997).

For the Hellenic civilizations, one of the salient characteristics of cultural development, since the Minoan Era (ca. 3200–1100 bc), is the architectural and hydraulic function of aqueducts used for the water supply in palaces and other settlements. The Minoan hydrologists and engineers were aware of some of the basic principles of water science and the construction and operation of aqueducts. These technologies were further developed by subsequent civilizations. Advanced aqueducts were constructed thereafter by the Hellenes and, especially, by the Romans, who dramatically increased the application scale of these structures, in order to provide the extended quantities of water necessary for the Roman lifestyle of frequent bathing (Hodge 1992; Kaiafa 2008). Simmons (1887) stated that the Romans appear to have got their knowledge of aqueduct building, like most of their other knowledge, from the Hellenes. Also, Castellani & Dragoni (1997) have supported that the expertise in central Italy on tunneling can possibly derive from the previous Hellenic experience in that field and moreover, in this context, one finds that the skill of planning difficult, sophisticated tunneling works was probably known and applied in Hellas well before the time of the Samos aqueduct.

The aim of this paper is to present the evolution of technological developments relevant to underground aqueducts in Hellas through the centuries. The hydraulic features of representative aqueducts with underground sections from Megara, Samos Island, Athens, Polyrrhenia (Crete), ancient Korinthos, Lyttos (Crete), Thessaloniki, and Aposelemis (Crete) are presented and discussed. In addition, major aqueducts with underground sections are presented with their hydraulic and historical characteristics. Aqueducts with inverted siphons are also included and discussed.

PREHISTORIC TIMES

The basic principles of aqueduct construction had been discovered by the Minoans but mainly later, by Hellenes in the Classical and Hellenistic periods. However, Roman aqueducts were arguably more common, larger in scale, and capable of transporting larger amounts of water than their Minoan, Etruscan, and Hellenic predecessors (Mays et al. 2007; Angelakis & Spyridakis 2013).

Bronze Age (ca. 3200–1100 bc)

In Minoan Crete, the technology of transporting water by aqueduct to palaces and other settlements was well developed as early as the Early Minoan Era (ca. 3000 bc). Frequent earthquakes may locally have caused a decline of aquifer levels and made it necessary to transport water from longer distances (Angelakis et al. 2007). In the Minoan palace of Knossos and Malia, the towns Gournia and Vathypetro and the houses at Tilissos water supply was based on aqueducts. In most of these aqueducts water was transported by open or covered surface channels. In Knossos water was transported by closed terracotta pipes and/or open or covered channels of various dimensions and sections of gravity aqueduct of about 0.7 km long (Figure 1). Similar terracotta pipes have been found in other Minoan settlements such as Tilissos, Gournia, and Vathypetro, as well as in the Caravanserai, located to the south of Knossos palace. Parts of it were an underground structure.
Figure 1

Part of Knossos palace aqueduct (Evans 1964).

Figure 1

Part of Knossos palace aqueduct (Evans 1964).

Mycenaean period (ca. 1600–1100 bc)

Advanced hydraulic techniques were developed during the Mycenaean period (ca. 1600–1100 bc). These hydraulic works include dams, artificial reservoirs, cisterns, bathrooms, etc. A great example of the use of tunnels for drainage purposes is that of the Akraifnio drainage tunnel, about 2.2 km long, constructed by the Minyans in 1300 bc in order to drain the Kopais Lake and use the land for agriculture (Figure 2). The tunnel had a height of 1.8 m, and a width of 1.5 m. A total of 16 vertical shafts were excavated along the axis of the tunnel and through those the tunnel was excavated (Tsatsanifos 2007).
Figure 2

Longitudinal section of the Minyes tunnel.

Figure 2

Longitudinal section of the Minyes tunnel.

HISTORICAL PERIODS

Archaic period

In the archaic (ca. 750–490 bc) period of the Hellenic civilization, aqueducts, cisterns, and wells were similar to those built by the Minoans and Mycenaeans. However, the scientific and engineering progress during those stages enabled the construction of more sophisticated structures. Bobek (1962), Goblot (1963), and Troll (1963) refer to the extensive use of water collection and transportation tunnels in Hellas dating back to 700 bc.

Megara aqueduct

At Megara in West Attica, Hellas, several stretches of an underground canal with tubing, dated to archaic period, have been found (Malacrino 2010). Specifically, this underground aqueduct is discovered in a rural area of Megara (2012, Orkos area) by archaeologists of the Third Ephorate of Prehistoric and Classical Antiquities. It is considered to have been constructed in the 6th century bc by Eupalinos of Megara. The aqueduct consists of a network of shafts, cisterns and conduits, which collects and transports water by gravity to the city's central water reservoir, known as Theagenes’ Spring or Fountain (built in the early 5th century bc). This aqueduct displays similarities with the famous aqueduct of Samos, from both the technical characteristics and the whole design. The water supply system of Megara may be considered as an example of a conduit with a storage basin at its end. Two lines of terracotta pipe led ground water and spring water to a double reservoir of an area of 13.7 × 17.9 m2. In front of it and connected to it was another basin in order to draw the water from here (Fahlbusch 2008). Vertical shafts are distributed on the ground surface. Initially they served to keep the orientation of the alignment for ventilation and for the removal of excavated material during the opening procedure of the tunnels and then, for maintenance and ventilation of the aqueduct. Τhe water tunnel of the south underground fountain of Megara is shown in Figure 3.
Figure 3

Water capture tunnel of the south underground fountain of Megara.

Figure 3

Water capture tunnel of the south underground fountain of Megara.

The Eupalinos tunnel or Eupalinian aqueduct (in Hellenic: ‘Efpalinion orygma’)

One of the oldest aqueduct in Hellas is the tunnel of Samos, which is one of the greatest engineering achievements of ancient times. The tunnel, was presumably completed between 550 and 530 bc, during the tyranny of Polycrates, and it was in operation until the 5th century ad (Koutsoyiannis et al. 2008). It is a 1,036 m long tunnel with about 4 m2 cross section, built to serve as an aqueduct, supplying fresh water from an inland spring to the ancient capital of Samos, which today is called Pythagorean (Figures 4(a) and 4(b)). The excavation of the tunnel lasted for 10 years, while it remained in operation until the 5th century ad and then it was abandoned and forgotten. The tunnel crosses Mount Kastro, consisting of solid limestone, and was excavated from both ends (amfistomon, ‘having two openings’, as Herodotus, History, Γ, 60 mentions). Today, it is very common that tunnels are constructed from two openings to reduce construction time and cost. High-tech geodetic means and techniques like global positioning systems and laser rays are used to ensure that the two fronts will meet each other. The great achievement of Eupalinos (Eupalinus of Megara), Engineer is that he did this using the simple means available at that time; apparently, however, he had good knowledge of geometry and geodesy (Angelakis & Koutsoyiannis 2003). However, the question still exists, why did Eupalinos construct the tunnel instead of an open conduit along the periphery of the hill? The question remains open and requires justification.
Figure 4

Tunnel of Eupalinos: (a) sketch (up: vertical section; down: horizontal plan), and (b) general view with sloped channel (Koutsoyiannis et al. 2008).

Figure 4

Tunnel of Eupalinos: (a) sketch (up: vertical section; down: horizontal plan), and (b) general view with sloped channel (Koutsoyiannis et al. 2008).

The Eupalinos tunnel was also the longest tunnel of its time. A visit to the tunnel today reveals its full magnificence. Except for some minor irregularities, the southern half is remarkably straight. The craftsmanship is truly impressive, both for its precision and its high quality.

The Hymettos aqueducts

This is usually confused with the Peisistratian aqueduct (a truly gigantic technical work) implemented by Peisistratos (ca. 510 bc), as genuine tyrants, in order to offer water to the Athenian people. The Hymettos aqueduct was constructed later (late 5th or early 4th century bc) and it consists of tunnels and wells up to 14 m deep (De Feo et al. 2013). Locations of ancient hydraulic works including major aqueducts, discovered in recent excavations around the National Garden of Athens, are shown in Figure 5. The descendants of the aqueduct comes out of the city to seek the waters of from the river Ilissos, either on the surface with the speculated Nine-tap fountain (perhaps somewhere around the intersection of Callirhoe and Anapafseos streets or, more likely, to the northeastern sources of Ilissos). Its distance from the Acropolis is about 7.5 km (Chiotis & Chioti 2012). It is definitely indeed a huge technological achievement (Figure 6). This aqueduct is hosted for the most part in a tunnel, up to 14 m deep.
Figure 5

Locations of ancient hydraulic works discovered in recent excavations around the National Garden of Athens: P1 and P2 of the Peisistratean pipeline, H of the Hadrianic aqueduct, K of the Kimonian pipeline net and Aq of various aqueducts including Hymettos aqueduct (Chiotis & Chioti 2012).

Figure 5

Locations of ancient hydraulic works discovered in recent excavations around the National Garden of Athens: P1 and P2 of the Peisistratean pipeline, H of the Hadrianic aqueduct, K of the Kimonian pipeline net and Aq of various aqueducts including Hymettos aqueduct (Chiotis & Chioti 2012).

Figure 6

Technical details of the tunnels of Peisistratos aqueduct (Tassios 2007).

Figure 6

Technical details of the tunnels of Peisistratos aqueduct (Tassios 2007).

Classical and Hellenistic periods (ca. 490–146 bc)

As Crouch (1993) pointed out, the highly developed urban water systems of Classical (ca. 490–323 bc) and Hellenistic times (ca. 323–146 bc) were based on careful study of the behavior of water integrated with equally knowledgeable manipulation of human economic and political behavior. In Magna Graecia, the inhabitants of Akragas asked the engineer Phaeax to construct a system of tunnels for collecting and transporting water (section 2 m by 1 m) to feed about twenty fountains in the whole city. The total length of these tunnels beneath the ancient city surpasses 15 km (Tassios 2004). It is worth mentioning, also, the water collection system of tunnels for the great Peirinis fountain in Acrocorinthos (Tassios 2004). Finally, the qanat system for collecting, transporting and depositing water was extensively developed in ancient Athens. Shafts – water wells were joined, forming huge underground projects (Figure 7) (Chiotis 2011).
Figure 7

Qanat system in Athens (Mitteilungen des Deutschen Archäologischen Instituts, Athenische Abteilung in Chiotis (2011)).

Figure 7

Qanat system in Athens (Mitteilungen des Deutschen Archäologischen Instituts, Athenische Abteilung in Chiotis (2011)).

Around 420–400 bc the aqueduct at Olynthos City, Chalkidiki was constructed (Bakalakis 1967). In the 4th century bc the aqueduct at Strymi City, Molivoti Peninsula, Thrace was constructed (Bakalakis 1967). Around 300 bc the complex irrigation system, including tunnels, at Perachora, Korinth area was constructed (Lazos 1993), and in the 3rd century bc the aqueducts at Aegina, Skyros Islands and Kyrini, north Africa, were constructed (Vavliakis 1997).

Aqueducts of Polyrrhenia

Hellenistic Polyrrhenia lies in the mountainous hinterland of the Kissamos district in western Crete. It has been one of the most important cities in Crete, in a naturally protected site. Christodoulakos & Markoulaki (2011) and Voudouris et al. (2013) reported that the water supply of the city was based on two aqueducts of the Hellenistic period (from the end of 4th to the end of 1st century bc), which have been restored and reused during the Roman times, being still in use today. They are carved by tunneling through natural marly limestones on the southern low slopes of the city. The aqueduct (tunnel) no. 1 ends in the modern village's central square. Christodoulakos & Markoulaki (2011) have visited the tunnel in its length of about 65 m (Figure 8(a)). Its continuation is obstructed by stalactites.
Figure 8

Polyrrhenia aqueducts: (a) exit of the tunnel and channel of aqueduct 1, and (b) tunnel with channel of aqueduct 2 along the semicircular tower of the Hellenistic wall (Christodoulakos & Markoulaki 2011).

Figure 8

Polyrrhenia aqueducts: (a) exit of the tunnel and channel of aqueduct 1, and (b) tunnel with channel of aqueduct 2 along the semicircular tower of the Hellenistic wall (Christodoulakos & Markoulaki 2011).

The height of the tunnel (aqueduct 1) is at least 2 m and its width of about 0.80 m. There is no distinct conduit or channel in the bottom of the tunnel, and the water flows along the mild slope. At the exit of the tunnel, along its western wall, a secondary, shallow rock-cut channel runs at a level of +1.00 over the ‘floor’ of the tunnel (Voudouris et al. 2013). In the southeastern edge of the modern village, one can see the end of another similar tunnel. This tunnel (aqueduct 2, Figure 8(b)), constructed roughly in the same way as the previous one, supplies the village with a continuous flow of water all year long (Christodoulakos & Markoulaki 2011). There is a channel on the floor of the tunnel, partly constructed with stones, partly carved into the rock, which ends up at a fountain. At a horizontal distance of 98.5 m, on a roadway, there is a rock-cut staircase going down the tunnel. According to the inhabitants, the staircase was connected to the tunnel. Near the tunnel exit there is a rectangular hole measuring 2.00 m × 1.50 m that also led to the tunnel (Voudouris et al. 2013).

Based on hydrogeological conditions of the surrounding area, it is assumed that the tunnels collected water from groundwater through wells, rather than from springs. It is worth noting that aqueducts ended in cisterns (at first aqueduct the dimensions of the cistern are 18.20 m × 6.70 m × 3.50 m) to ensure water storage for emergency cases such as prolonged drought (Christodoulakos & Markoulaki 2011).

Roman period (ca. 146 bcad 330)

Aqueduct of Hortiatis

Α water collection system qanat is located in the northern slopes of mount of Hortiatis, in Agia Paraskevi region, at an altitude 575–565 m, in order to supply water to the city of Thessaloniki from spring water and through percolation of rainfall. Tunnel and transfer conduit are 20 km long, the largest in total length of the Hellas. This system is dated to the first century ad (Roman era) and restored several times in the following centuries. It is the only surviving monument of this kind in Central Macedonia (Manoledakis & Makri 2008).

The aqueduct starts in the exit point of the qanat and passes over an impressive water bridge, which stands at the entrance of Hortiatis village. This bridge, which is used only for water transfer, has a length of 223 m and a maximum height of 20 m. It is made of stones and bricks, the one over the other. Its thickness reaches up to 8 m in the north part, while in the centre there are two big airy arched openings, the larger one with height 8.5 m and with biggest width 5.3 m. At the highest point there was a rectangular pipe 0.5 m wide, that could receive clay pipes for the transportation of water. Then, the aqueduct mainly in the form of covered water channel passed through the city of Panorama, outside the town of Asvestochori and reaches the Acropolis, from where the water enters to the city of Thessaloniki and was distributed in public baths and fountains. The qanat is composed of two lines of tunnels with a total length of 74 m: one of them at a maximum depth of 6.40 m, and the other at a maximum depth of 7.90 m (Vavliakis et al. 1995). Water is drained over an area of approximately 600 m2. Specifically, the qanat consists of the following (Figure 9(a)):
  • Two underground tunnels of total length 74 m, with an average height 1.50–1.60 m and a width of 0.56–0.75 m. The view of one of these tunnels is shown in Figure 9(b). Water flows on the bottom right channel while a path is on left side for maintenance of the tunnel.

  • Three shafts/wells (1, 2, 3), from which the two of which (1, 2) communicate with the surface, but the third is closed.

  • Four water reservoirs (a, b, c, d).

Figure 9

Hortiatis aqueduct: (a) ground plan, and (b) view of one of the tunnels (http://www.hydriaproject.net/en/greece-hortiatis-qanat/relevance7).

Figure 9

Hortiatis aqueduct: (a) ground plan, and (b) view of one of the tunnels (http://www.hydriaproject.net/en/greece-hortiatis-qanat/relevance7).

There are two main water entry points. The first of these is located at reservoir (d), follows the route of tunnels E, C, B, and A and after traveling through a narrow pipeline reaches the end tank, where it is chlorinated. The second one is located at the base of the shaft (2) following the route of tunnel D, and then via pipeline arrives at the main collector.

The aqueduct of Lyttos

The aqueduct was obliged to abandon the contours of the mountains to traverse the lower terrain towards the city, near the village of Teixos in Crete. Oikonomakis (1984) calculated that if the aqueduct proceeded here using only gravity flow, its height would have been between 35–40 m. However, the drum of a stone pipe found nearby, would suggest that the city was served by an inverted siphon formed of a series of stone pipes (Figure 10), similar to those supplying Patara and Aspendos. Oikonomakis (1984) also proposed the presence of another siphon bridge along the Chersonisos aqueduct, at Xerokamares, where it crosses the Aposelemis River.
Figure 10

Detail of the stone pipe of the Roman aqueduct of Lyttos, Crete.

Figure 10

Detail of the stone pipe of the Roman aqueduct of Lyttos, Crete.

Fundana aqueduct

This aqueduct was probably constructed during the Roman period for transporting the good quality Fundana spring water to Knossos in Crete (Xanthoudides 1927). It is 11 km long; starting from the spring of Fundana of Q = 7.9 L/s in 1867 (Spanakis 1981). It was used for water supply of Knossos at that time from Fundana spring. However, the Fundana aqueduct was reconstructed during the Egyptian period (ca. 1830–1840). At that time the tunnel at Scalani village area was also reconstructed with a 1.00 × 2.00 m2 cross section and 1,150 m in length. In this period the famous water bridge in Agia Irini, Spilia, was also constructed, by which the Fundana aqueduct was connected with that of Morozini aqueduct implemented during the Venetian period (ca. 1204–1669) and the water supply of Iraklion city was highly improved (Stavranides 1969). This aqueduct is still in use today by replacing the opened conduit with a PVC-pipe.

Hadrianic aqueduct

After a period of drought in Athens, around ad 125, the construction of the Hadrianic aqueduct started and was concluded in ad 140. It is a complex aqueduct, whose trunk consists of a 20 km long tunnel from Mountain Parnis foothills to the centre of Athens.

The Hadrianic aqueduct was a benefaction of the Roman Emperor Hadrian to the city of Athens. It differs significantly from the rest of the Roman aqueducts in Hellas, e.g. at Nicopolis, Korinthos, Mytilene, Knossos, Samos and elsewhere, because it is totally underground from the foothill of Parnis Mt. to the Lycabettus Hill in Athens, over a distance of circa 20 km. It taps springs from the foothills of Parnis Mountain, groundwater over most of its course and perched aquifers, wherever available. Its main body is composed of a tunnel and wells at regular intervals of 35 to 40 m. The tunnel is 0.5 m wide and 1.2 to 1.3 m high on average and runs at about 25 m below the ground surface (Figure 11). The tunnel passes below the Kifissos river and the adjacent streams. The northern end of the tunnel at the Olympic Village lies ca. 10 m below the water table; the tunnel is connected to the ground surface through an inclined gallery for the collection of spring waters, which used to flow into the gallery along stone-built plastered channels. It was also fed with local water resources by means of lateral branches, the most significant of which was that at Chalandri area, which collected water from springs of the Pentelikon Mountain.
Figure 11

The Athens Hadrianic aqueduct.

Figure 11

The Athens Hadrianic aqueduct.

The sustainability of the aqueduct thanks to the catchment of groundwater has been stressed by Chiotis & Marinos (2012). It never stopped supplying water, even after the collapse of the tunnel near the Agios Dimetrios church at Ampelokipi, where the water overrun to the surface and was therefore considered as a spring. In the second half of the 19th century it was cleaned and reused and remained the main water supply of Athens up to 1931, when the Marathon reservoir was completed. It was dug in easily excavated rocks, such as talus cone breccia, Upper Miocene red clays and marls of the lignite bearing lacustrine sediments of the Kalogreza basin and in Athenians schists. The main geotechnical problem was the occasional tunnel collapse, particularly in the Athenian schists, and this made it necessary to support the roof locally, usually with prefabricated terracotta bricks, either rectangular or arcuate ones.

Ancient Korinthos–Hadrian's aqueduct

Based on investigations of Lolos (1997) who has traced the entire course of the aqueduct and described the surviving remains in detail, this Hadrian aqueduct with a length of 84–85 km (the longest and the most voluminous Roman aqueduct of ancient Hellas) was constructed by the Emperor Hadrian during the period ad 117–138 in order to transfer water from Stymfalia basin (altitude +620 m) to ancient Korinthos (Figure 12(a)). The type of construction was dependent on the type of geological formation (limestone, marls, alluvial deposits) on which the aqueduct was going through. The aqueduct included three underground tunnels and 22 bridges along its route (Figure 12(b)).
Figure 12

(a) The course of the Hadrianic aqueduct, and (b) underground gallery (Lolos (1997) with modifications from Voudouris (2012)).

Figure 12

(a) The course of the Hadrianic aqueduct, and (b) underground gallery (Lolos (1997) with modifications from Voudouris (2012)).

The first tunnel (Siouri tunnel) with a length of 1,070 m, 1.50 m × 1.90 m at the entrance and 1.60 m × 2.50 m at its exit and maximum depth 80 m below ground surface (b.g.s), was dug partly in limestones and partly in marls. The second tunnel, called Prathi, measures 750 m in length, 1.60 m × 1.80 m at the entrance and 1.60 m × 1.40 m at its exit, at depth 20 m b.g.s. The third tunnel, called Spathobouni, was dug in marls 1.00 m × 1.70 m at 20 m b.g.s. (Lolos 1997).

Aspendos aqueduct

Inverted siphons were commonly used to cross deep valleys (over 50 m) (Kessener & Piras 2008; Nikolic 2008). Inverted siphons are pipes that were operated under pressure. These were mostly constructed using lead pipes in the Western Roman Empire, where lead mining was common (De Feo et al. 2013). In the eastern part of the Empire, stone siphons, constructed from hollowed ashlars of limestone, marble or basalt, were more common (e.g. the aqueducts of Patara, Aspendos, and Smyrna). Terracotta pipes, with thick walls, were also used. In Aspendos, one of the most spectacular examples of the use of inverted siphons within aqueducts can be observed (Figure 13). The aqueduct of Aspendos was built in the ca. 2nd–3rd century ad.
Figure 13

Schematic representation of the triple inverted siphon system in the Aspendos aqueduct (De Feo et al. 2013).

Figure 13

Schematic representation of the triple inverted siphon system in the Aspendos aqueduct (De Feo et al. 2013).

It transported water to the town from a spring located 20 km to the north of the city (Kessener & Piras 2008). The aqueduct featured a masonry channel with an open surface flow following the contour of the land. The 1.5 km long valley between the hills and the acropolis was crossed using a system of three inverted siphons. In this system, water was carried across the valley under pressure in a closed pipeline. This pipeline started from a header tank on the hill and brought the water up to receiving tanks on the two towers, and on the acropolis (De Feo et al. 2013).

The Romans, whose Empire replaced the Hellenic rule in most parts of the Hellenic world, inherited the aqueduct technologies and further developed them mainly by changing their application scale from small to large and implementing them to several large cities. More on Hellenic Roman aqueducts including underground hydraulic works are given by De Feo et al. (2013) and at: http://www.romanaqueducts.info/aquasite/index.html.

The Byzantine period and Venetian rule (ca. ad 330–1538)

In the Byzantine period, the construction of aqueducts was abandoned and emphasis was put on the construction of tanks or cisterns. The tanks and cisterns were constructed in order to collect rain or spring water.

Ottoman period

The Ottoman period is characterized by the construction of aqueduct-like qanats and the exploitation of springs. In Phyllida (Serres, North Hellas) more than 18 aqueduct-like qanats of a length ranged from 35 m to 4,000 m each, and are described by Vavliakis (1989). These hydraulic works are used for water supply of villages and monasteries since the Ottoman occupation (17th–19th centuries), and some of them are in operation still today. Few are not in operation due to the destruction from floods and earthquakes, clogging of tunnel from branches of trees or shrubs roots, deposition of calcium salts, etc. (Voudouris et al. 2013).

Present times

The major hydraulic tunnels of present times were associated with the projects for the water supply of Athens. As has been already mentioned, the inhabitants of Athens had to develop basic water collection and distribution systems for the water supply of the city. The Adrian aqueduct continued to be the major water supply structure for 17 centuries after its construction. At the time of Athens' liberation from the Turkish army in 1830, the city's water supply problem was critical and demanded immediate attention. The new city authorities commissioned a number of projects to rebuild and renovate existing local water supply works, such as Adrian aqueduct system. It was cleaned of accumulated debris, repaired, and put into operation again in 1840. However none of the above endeavors provided a real solution to Athens’ water problem. The municipal taps, 55 in number, that existed in Athens contributed little to minimal for daily water consumption needs and were totally inadequate. The men, who were carrying and selling water in Athens from the neighboring villages, such as Kifissia and Maroussi, were very popular and earned lot of money during that period.

In 1922, with the huge influx of Hellenes refugees from Asia Minor, Athens underwent a sharp increase in population that had a devastating effect on the city's water supply. In 1925 a contract was signed between the Hellenic Government, the Bank of Athens and the American firm ULEN for the financing and construction of the new water supply works. The first major project was the construction of the Marathon Dam (1926–1929). Over 900 people were involved in the construction of the dam, with a total height of 54 m and a length of 285 m. It is a gravity dam considered unique because it is entirely panelled externally with the unique Pentelikon white marble. The dam is founded on crystalline limestones close to the contact with water tight schists. Minimal impermeabilization grouting was performed. The operational volume of its reservoir is 40.8 million m3. Today it is used as a daily-to-monthly regulating reservoir, the daily consumption in Athens being more than one million cm3. The Boyati Tunnel (13.4 km long, 2.6 m wide and 2.1 m high) was constructed to transport water from the Marathon reservoir to a new water treatment plant in Athens (Figure 14).
Figure 14

The water cycle in Athens in the modern era (Skotsimara et al. 2008).

Figure 14

The water cycle in Athens in the modern era (Skotsimara et al. 2008).

The continuously increasing need of the expanding capital demanded more water and, in 1956, the water from the Yliki Lake was added to the system until 1981 when the operation of the Mornos dam and aqueduct officially began. The Yliki lake (of 580 million m3 operational volume) that already had been enhanced by the waters of the drainage of the Lake Kopais through the tunnel of New Karditsa, is a natural lake in a karst environment and most of the lake waters are lost through sink holes, directly or indirectly to the Evoikos sea. Thus, water cannot be stored or regulated and has to be conveyed straight to its use. The Yliki, aqueduct, 66.7 km long conveys water to Athens by pumping. Now the Yliki lake and aqueduct is used only in contingency management and in case of emergency. This was the case with the drought of 1989–1991 when the Mornos reservoir reached the lowest operation level. A wide exploitation of the karstic waters of the Viotikos karstic basin was also implemented. The overexploitation of groundwater had to be compensated afterwards through an interannual management. This drought accelerated the construction of the Evinos aqueduct, diverting water from the regulative new Evinos reservoir to the Mornos one.

The Mornos dam is a 126 m high earth fill dam with central clay core. It is efficient founded on flysch. The majority of its reservoir is again on the watertight flysch, except in the area of the Pyrnos ridge where karstic limestones outcrop, conveying their infiltration to the Korinthiakos Gulf. A very important isolation has been made, one of the few in the world, along a length of 2.6 km, where a bituminous concrete were applied on the limestone ground surface. The operational volume of Mornos reservoir, of 630 million m3, much higher than the potential of the Mornos dam catchment area. Thus, designed for an over annual operation and ready to receive additional water diverted from adjacent basins as is now the case from the Evinos dam and reservoir. The Mornos aqueduct, which transports water from the Mornos reservoir to Athens, is the second longest aqueduct in Europe. It has a total length of 188 km, made up of 15 tunnels (71 km) of 3.2 m diameter, 12 siphons crossing valleys (7 km) and 15 canals (110 km). It was the first time of a tunnel boring machine (TBM) use in Hellas for the excavation of the first tunnel of the aqueduct, the Giona tunnel (14.75 km) and the Kirfi tunnel (9.3 km).

The Giona tunnel had to cross the High Giona Mountain, under a maximum cover of 1,700 m, composed almost entirely of limestones, from the Triassic to the Cretaceous age (Figure 15). The mountain is full with karstic features with big springs at its periphery to the Corinthian Gulf. A big initial concern was on the method to apply for the construction in this highly karstic environment and if a TBM could be used. Finally, based on a thorough hydrogeological assessment it was concluded that the interior of the mass was preserved from karstic processes, due to its tectonic history and no karstic waters, either transit or permanent had to be encountered. Indeed in the exception of two conduits the limestone was absolutely non-karstic and the TBM construction was very efficient.
Figure 15

The Mornos–Athens aqueduct, crossing the karstic mountain of Giona. The karstic process was not developed in depth at the level of the tunnel (Marinos 2005).

Figure 15

The Mornos–Athens aqueduct, crossing the karstic mountain of Giona. The karstic process was not developed in depth at the level of the tunnel (Marinos 2005).

Finally, the last major project, which has provided Athens with additional water in 2001, is the Evinos River diversion to the Mornos Impounding Reservoir, consisting of the Evinos dam (of 113 million m3 operational volume) and a diversion tunnel. Work began on the Evinos project in 1992, pressed by the drought already mentioned and the whole project was completed in 2001. The major structures of the project are a 120 m high earthfill dam, able to divert the 220 million m3 of its hydrological basin and the 29.4 km long Evinos – Mornos tunnel with a 4.2 m maximum excavation diameter and an internal diameter of 3.50 m. The tunnel is one of the longest hydraulic tunnels in the world realized with the four TBMs. The adverse geological conditions, the high cover and the short construction schedule were a great challenge for the successful construction of this tunnel (Grandori et al. 1995).

The tunnel was completed in just 2 years, 6 months ahead of the contractual schedule, which is considered to be a significant achievement given the project scale and the adverse geological conditions of the Pindos tectonically highly stressed zone (Figure 16). This was due to the right selection of the boring machines. In the outer parts where limestones or sandstone flysch prevails two open rock TBMs was selected. In the middle part approached through an intermediary access, two double shield TBMs were applied able to face the presence of weak siltstone flysch with frequent shears and with overboring devices to face convergence of the tunnel due to squeezing processes. The mean daily advance of all machines was more than 60 m per calendar day (Grandori et al. 1995).
Figure 16

Simplified geological longitudinal section of Evinos-Mornos tunnel (types of TBMs used) (Grandori et al. (1995) with modifications from S. Yannopoulos).

Figure 16

Simplified geological longitudinal section of Evinos-Mornos tunnel (types of TBMs used) (Grandori et al. (1995) with modifications from S. Yannopoulos).

Another ongoing project with major hydraulic tunnels is the one associated with the partial diversion of the Acheloos River to the Thessaly plain for water supply, irrigation and power generation purposes (Figure 17). The project consists of the Sykia Dam (150 m) and the diversion tunnel, of 17.4 km length and 4.9 ÷ 6 m internal diameter (6 m for 10.4 km and 4.9 m for 7 km), planned to transport water from the Sykia Dam to the Pefkofyto Hydroelectric Station. To the diversion project to mention the Messochora Dam (150 m) and the Messochora–Glystra tunnel (7.5 km) in the Acheloos basin as well as the Pyli Dam and the Pyli–Mouzaki tunnel in the Thessaly plain.
Figure 17

The major parts of the Acheloos River diversion project (Tsatsanifos & Michalis 2014).

Figure 17

The major parts of the Acheloos River diversion project (Tsatsanifos & Michalis 2014).

The Acheloos River diversion tunnel excavation was carried out by both sides (Drakotrypa and Petroto), either with TBM or with conventional means. An intermediate access was created from the village of Prosperous. Tunneling through limestone and chert advanced without any specific problems, except in brecciated zones. Tunneling through the flysch sequence dramatically slowed down the advancing rate (Sfeikos & Marinos 2004). The tunnel construction started in 1997, however, due to environmental reasons, its finalization has been stopped many times and although it broke through, still there are about 12.5 km to be lined. The whole project is in a halt based on a decision of the Hellenic High Court. Finally, many hydraulic associations with the construction of dams for power generation, were constructed by the Public Power Corporation of Hellas since the mid 1950s.

Recently, following the implementation of the Aposelemis dam (26 millions m3 usable volume) in the area of Iraklion, Crete, two major aqueducts were constructed, for water supply of Iraklion and Agios Nikolaos cities: one towards the east (Agios Nikolaos, 30 km), and the other in the west (Iraklion, 33 km). In addition, the dam is connected with the water treatment plant with a third shorter aqueduct (7 km) of which 3.72 km consists of two tunnels (2.07 + 1.65 km). Also the aqueduct of Agios Nikolaos includes a small tunnel (cistern) 0.68 km in length. Finally, the project includes a tunnel, at present (2015) under construction with a double shield TBM, of 3.5 km in length, 5 m in diameter and 15% slope, containing the 1.8 m pipe (Figure 18). It will divert floods from the Lasithi high plateau, today lost in sinkholes, to the Aposelemis reservoir.
Figure 18

The Aposelemis TBM tunnel.

Figure 18

The Aposelemis TBM tunnel.

Recently, following the implementation of the Aposelemis dam (26 million m3 usable volume) in the area of Iraklion, Crete, two major aqueducts were constructed, for water supply of Iraklion and Agios Nikolaos : one towards the east (Agios Nikolaos, 30 km), and the other in the west (Iraklion, 32.50 km). In addition, the dam is connected with the water treatment plant with a third shorter aqueduct (7 km) of which 3.64 km consists of two tunnels (2.05 + 1.59 km). Also, the aqueduct of Agios Nikolaos includes a small tunnel (cistern) 0.60 km in length. Finally, the project includes a tunnel, at present (2015) under construction with a double shield TBM, of 3.5 km in length, 5 m in diameter and 15% slope, containing the 1.8 m pipe. It will divert floods from the Lasithi high plateau, today lost in sinkholes, to the Aposelemis reservoir. The construction of Aposelemis TBM tunnel is shown in Figure 18.

EPILOGUE

The collected data show that ancient Hellenes were definitely aware of the importance of the availability of water. The transport of water over long distances was done with renowned aqueducts. So, spring water from the mountainous areas was collected and transferred by gravity via underground aqueducts, which were enclosed, vaulted and stone built (Angelakis et al. 2016). In Hellas, the technique of tunneling was developed and used since at least prehistoric times.

The construction of the aqueducts was based on the topography, hydrogeological, geological and climatic conditions, as well on the local culture. The Peisistratean aqueduct in Athens and the Eupalinos tunnel are the most famous aqueducts in the Archaic and Classical periods. Numerous aqueducts were constructed during the Roman period based on the principles and rules previously developed and implemented by the Minoans and Mycenaeans and had further improved by the Hellenes in the Classical and Hellenistic periods. Innovations of Roman engineers mainly related to the introduction of aqueducts, open type, with built stone roof free flowing channels of water, with constant slope and controlled the flow path (Kaiafa-Sarapoulou et al. 2016). Roman aqueducts are characterized by the existence of a central tank for division of the incoming water to several parts of the cities, such as Athens, Dion, Nikopolis, Dimitrias, Gythion, Chersonisos and others (Lolos 1997). Furthermore, the Romans developed aqueduct-like qanat technologies in different countries of Europe (Angelakis et al. 2016). The evolution of the major aqueducts with underground section in the Hellenic world are shown in Table 1.

Table 1

The evolution of the major aqueducts with underground section in the Hellenic world: selected references

Period Place Length (km)a Flow rate (m3/d) References 
1750 Knossos (Mavrocolympos) ≈0.70  Angelakis et al. (2007)  
1450 or 1300 bc Minyans tunnel for the drainage of Kopais Lake ≈2.20  Knauss et al. (1984)  
1st half 6th c. bc Megara aqueduct   Malacrino (2010)  
1st half 6th c. bc Aegina aqueduct   Vavliakis (1997)  
Late 6th c. bc Naxos aqueduct 0.22  Lambrinoudakis (2014)  
 De Feo et al. (2013)  
 Zarkadoulas et al. (2012)  
550–530 bc Eupalinos tunnel for water transfer at Samos Island 1,036 400 Sandstrom (1963)  
Kienast (1977)  
Apostol (2004)  
Olson (2012)  
http://www.romanaqueducts.info/aquasite/samosarchaic/index.html 
5th c. bc Ephesus (length of inverted siphon) 0.06  Ozkaldi et al. (2007)  
6th or 5th ca.bc Peirene, Korinthos   Robinson (2011)  
4th c. bc Hymettos (tunnel and wells up to 14 m deep, qanat-technology)   Chiotis & Chioti (2012)  
    De Feo et al. (2013)  
420–400 bc Aqueduct at Olynthos City, Chalkidiki   Bakalakis (1967)  
Classical Thebes, Kolonaki   Symeonoglou (1985)  
4th c. bc Aqueduct at Strymi City, Thrace   Bakalakis (1967)  
4th c. bc Polyrrhenia aqueduct 1, western Crete ≈0.065  Voudouris et al. (2013)  
4th c. bc Polyrrhenia aqueduct 2, western Crete ≈0.10  Voudouris et al. (2013)  
300 bc Aqueduct at Perachora, Korinthos area   Lazos (1993)  
3rd c. bc Aqueducts at Skyros Islands and Kyrini   Vavliakis (1997)  
2nd c. bc Smyrna aqueduct (length of inverted siphons) 4.00  Nikolic (2008)  
197–159 bc Pergamum aqueduct (length of inverted siphons) 3.50  Nikolic (2008)  
1st c. bc–1st c. ad Nikopolis, Epirus 50.00  De Feo et al. (2012)  
1st c. ad Fundana, Iraklion, Crete 1.15 682.56 Spanakis (1981)  
1st c. ad Lyttos aqueduct, Crete (stone inverted siphon)   Kaiafa-Saropoulou et al. (2016)  
1st c. ad Aqueduct of Hortiatis, Thessaloniki 0.074 360–528 Vavliakis et al. (1995)  
Roman Moria, Lesbos   De Feo et al. (2012)  
ad 125–140 Hadrianic aqueduct, Athens 20.00 7,000 Chiotis (2011); Chiotis & Chioti (2012)  
ad 117–138 Korinthos–Hadrianic aqueduct 2 tunnels of 1.70 & 0.75 80,000 Lolos (1997)  
2nd c. ad Kaystros Ephesus 40 9,000–35,000 De Feo et al. (2013)  
2nd–3rd c. ad Aspendos aqueduct (length of triple inverted siphon) 1.70 5,600 Nikolic (2008)  
    Kessener & Piras (2008)  
17th–19th c. ad 18 aqueducts-qanats of a length ranging from 35 m to 4,000 m each in north Greece   Vavliakis (1989)  
1922 Boyati Tunnel, Athens 13.40  Tsatsanifos & Michalis (2014)  
1981 Mornos aqueduct, Athens of 15 tunnels 71.00  Tsatsanifos & Michalis (2014)  
2001 Evinos aqueduct 29.40  Tsatsanifos & Michalis (2014)  
1985 Sykia diversion tunnel and Dam-Acheloos River 17.4  Tsatsanifos & Michalis (2014)  
1985 (construction start) Mesochora diversion tunnel and Dam- Acheloos River (under construction) 7.50  Tsatsanifos & Michalis (2014)  
2013–2015 Aposelemis tunnels (from dam to water treatment plant) 2 tunnels of 3.64 110,000  
2013–2015 Aposelemis tunnel (branch to Agios Nikolaos city)  0.68 25,000 http://www.hydroex.gr/projects/aposelemis-dam-water-treatment-and-supply-works-northern-crete-island 
2015–2016 Aposelemis TBM tunnel canyon Rosa, Crete (under construction) 3.50  http://www.hydroex.gr/projects/aposelemis-dam-water-treatment-and-supply-works-northern-crete-island 
Period Place Length (km)a Flow rate (m3/d) References 
1750 Knossos (Mavrocolympos) ≈0.70  Angelakis et al. (2007)  
1450 or 1300 bc Minyans tunnel for the drainage of Kopais Lake ≈2.20  Knauss et al. (1984)  
1st half 6th c. bc Megara aqueduct   Malacrino (2010)  
1st half 6th c. bc Aegina aqueduct   Vavliakis (1997)  
Late 6th c. bc Naxos aqueduct 0.22  Lambrinoudakis (2014)  
 De Feo et al. (2013)  
 Zarkadoulas et al. (2012)  
550–530 bc Eupalinos tunnel for water transfer at Samos Island 1,036 400 Sandstrom (1963)  
Kienast (1977)  
Apostol (2004)  
Olson (2012)  
http://www.romanaqueducts.info/aquasite/samosarchaic/index.html 
5th c. bc Ephesus (length of inverted siphon) 0.06  Ozkaldi et al. (2007)  
6th or 5th ca.bc Peirene, Korinthos   Robinson (2011)  
4th c. bc Hymettos (tunnel and wells up to 14 m deep, qanat-technology)   Chiotis & Chioti (2012)  
    De Feo et al. (2013)  
420–400 bc Aqueduct at Olynthos City, Chalkidiki   Bakalakis (1967)  
Classical Thebes, Kolonaki   Symeonoglou (1985)  
4th c. bc Aqueduct at Strymi City, Thrace   Bakalakis (1967)  
4th c. bc Polyrrhenia aqueduct 1, western Crete ≈0.065  Voudouris et al. (2013)  
4th c. bc Polyrrhenia aqueduct 2, western Crete ≈0.10  Voudouris et al. (2013)  
300 bc Aqueduct at Perachora, Korinthos area   Lazos (1993)  
3rd c. bc Aqueducts at Skyros Islands and Kyrini   Vavliakis (1997)  
2nd c. bc Smyrna aqueduct (length of inverted siphons) 4.00  Nikolic (2008)  
197–159 bc Pergamum aqueduct (length of inverted siphons) 3.50  Nikolic (2008)  
1st c. bc–1st c. ad Nikopolis, Epirus 50.00  De Feo et al. (2012)  
1st c. ad Fundana, Iraklion, Crete 1.15 682.56 Spanakis (1981)  
1st c. ad Lyttos aqueduct, Crete (stone inverted siphon)   Kaiafa-Saropoulou et al. (2016)  
1st c. ad Aqueduct of Hortiatis, Thessaloniki 0.074 360–528 Vavliakis et al. (1995)  
Roman Moria, Lesbos   De Feo et al. (2012)  
ad 125–140 Hadrianic aqueduct, Athens 20.00 7,000 Chiotis (2011); Chiotis & Chioti (2012)  
ad 117–138 Korinthos–Hadrianic aqueduct 2 tunnels of 1.70 & 0.75 80,000 Lolos (1997)  
2nd c. ad Kaystros Ephesus 40 9,000–35,000 De Feo et al. (2013)  
2nd–3rd c. ad Aspendos aqueduct (length of triple inverted siphon) 1.70 5,600 Nikolic (2008)  
    Kessener & Piras (2008)  
17th–19th c. ad 18 aqueducts-qanats of a length ranging from 35 m to 4,000 m each in north Greece   Vavliakis (1989)  
1922 Boyati Tunnel, Athens 13.40  Tsatsanifos & Michalis (2014)  
1981 Mornos aqueduct, Athens of 15 tunnels 71.00  Tsatsanifos & Michalis (2014)  
2001 Evinos aqueduct 29.40  Tsatsanifos & Michalis (2014)  
1985 Sykia diversion tunnel and Dam-Acheloos River 17.4  Tsatsanifos & Michalis (2014)  
1985 (construction start) Mesochora diversion tunnel and Dam- Acheloos River (under construction) 7.50  Tsatsanifos & Michalis (2014)  
2013–2015 Aposelemis tunnels (from dam to water treatment plant) 2 tunnels of 3.64 110,000  
2013–2015 Aposelemis tunnel (branch to Agios Nikolaos city)  0.68 25,000 http://www.hydroex.gr/projects/aposelemis-dam-water-treatment-and-supply-works-northern-crete-island 
2015–2016 Aposelemis TBM tunnel canyon Rosa, Crete (under construction) 3.50  http://www.hydroex.gr/projects/aposelemis-dam-water-treatment-and-supply-works-northern-crete-island 

aLength of the underground sections.

The hydraulic technology of aqueducts is characterized by its durability and sustainability, although works are usually expensive, both in construction and maintenance. Several underground aqueducts have been operated for a long time with some of them being in operation until now.

ACKNOWLEDGEMENTS

The authors would like to thank Dr A. Kaiafa-Saropoulou and E. Chiotis for the valuable information about the Roman aqueducts in Hellas, as well as Mr Kostas Brilakis for information about Aposelemis aqueduct. Part of this review was presented at the 2nd IWA International Workshop on Evolution of Qanats and Relevant Hydraulic Technologies, November 8–10, 2015, Yazd, Iran, and published in its Proceedings (A. Semsar Yazdi and A. R. Bahri, eds): Voudouris, K., Tsatsanifos, C., Yannopoulos, S., and Angelakis, A. N. (2015). Evolution of underground aqueducts in Hellas through the centuries, pp. 89–110.

REFERENCES

REFERENCES
Angelakis
A. N.
Koutsoyiannis
D.
2003
Urban Water Engineering and Management in ancient Greek times
. In:
The Encyclopedia of Water Science
(
Stewart
B.A.
Howell
T.
, eds).
CRC Press
,
Dekker, NY
, pp.
999
1007
.
Angelakis
A. N.
Savvakis
Y. M.
Charalampakis
G.
2007
Aqueducts during the Minoan era
.
Water Science and Technology, Water Supply
7
(
1
),
95
102
.
Angelakis
A. N.
Spyridakis
S. V.
2013
Major urban water and wastewater systems in Minoan Crete, Hellas
.
Water Science and Technology, Water Supply
13
(
3
),
564
573
.
Angelakis
A. N.
Voudouris
K.
Mariolakos
I.
2016
Groundwater utilization through the centuries focusing on the Hellenic civilizations
.
Hydrogeology Journal
24
(
5
),
1311
1324
.
Apostol
T.
2004
The Tunnel of Samos
.
Engineering and Science
67
(
1
),
30
40
.
Bakalakis
G.
1967
Strymi archaeological excavation. Scientific Yearbook of the Philosophy Faculty
.
Aristotle University of Thessaloniki
,
Thessaloniki, Hellas
.
Bobek
Η.
1962
Iran. Themen zur Geographie und Gemeinschaftskunde. hrg. V. WW. Puls, Frankfurt
.
Castellani
V.
Dragoni
M.
1997
Ancient tunnels: from Roman outlets back to the early Greek civilization
.
Proceedings of the 12th International Congress of Speleology
3
,
265
268
.
Chiotis
E. D.
2011
Water supply and drainage works in the Agora of ancient Athens
. In:
Proc. of International Conference ‘The Agora in the Mediterranean from Homeric to Roman Times’
,
Kos
,
14–17 April 2011
, pp.
165
180
.
Chiotis
E. D.
Chioti
L. E.
2012
Water supply of Athens in the antiquity
. In:
Evolution of Water Supply Through the Millennia
(
Angelakis
A. N.
Mays
L. W.
Koutsoyiannis
D.
Mamassis
N.
, eds).
IWA Publishing
,
London
,
UK
,
Chapter 16
, pp.
407
442
.
Chiotis
E. D.
Marinos
P. G.
2012
Geological aspects on the sustainability of ancient aqueducts of Athens
.
Bulletin of Geological Society of Greece
46
,
16
38
.
Christodoulakos
Y.
Markoulaki
S.
2011
Water Supply of Polyrrhenia
. In:
Proceedings of the 11th International Cretological Congress
,
Rethymnon
,
Hellas
,
21–27 October 2011
.
Crouch
D. P.
1993
Water Management in Ancient Greek Cities
.
Oxford University Press
,
Oxford
,
UK
.
De Feo
G.
Laurano
P.
Mays
L. W.
Angelakis
A. N.
2012
Water Supply Management Technologies in the Greek and Roman Civilizations
. In:
Evolution of Water Supply throughout Millennia
(
Angelakis
A. N.
et al
, eds).
IWA Publishing
,
London
,
UK
,
Chapter 14
, pp.
351
382
.
De Feo
G.
Angelakis
A. N.
Antoniou
G. P.
El-Gohary
F.
Haut
B.
Passchier
C. W.
Zheng
X.-Y.
2013
Historical and technical notes on aqueducts from prehistoric to medieval times
.
Water
5
(
4
),
1996
2025
.
Evans
S. A.
1964
The Palace of Minos at Knossos: A Comparative Account of the Successive Stages of the Early Cretan Civilization as Illustrated by the Discoveries
.
Macmillan and Co.
,
London
, pp.
1921
1935
,
Vols I–IV. Reprinted by Biblo and Tannen, New York, USA
.
Fahlbusch
H.
2008
Municipal water supply in antiquity: a historical introduction. Retrieved from http://www.romanaqueducts.info/webteksten/waterinantiquity.htm
.
Goblot
H.
1963
Dans l'Ancien Iran les Techniques de l'eau et la Grande Histoire
.
Annales: Economies-Societes-Civilizations
18
(
3
), p.
499
.
Grandori
R.
Jaeger
M.
Antonini
F.
Vigl
L.
1995
Evinos-Mornos Tunnel – Hellas. Construction of a 30 km long hydraulic tunnel in less than three years under the most adverse geological conditions
. In:
Proceedings 1995 Rapid Excavation and Tunnelling Conference – RETC
, pp.
747
767
.
Hodge
Α. Τ.
1992
Roman aqueducts and water supply
.
London
,
UK
.
Kaiafa
A.
2008
Water and Sanitation systems in the Hellenistic and Roman periods in Macedonia, Doctoral Dissertation, Dept. of Architecture, Aristotle University
(
in Hellenic
).
Kaiafa-Saropoulou
A.
Voudouris
K.
Lolos
J.
Angelakis
A. N.
2016
Hydro-Technologies in Hellas: Aqueducts in Roman period.
School of Rural and Surveying Engineering, Aristotle Univ. of Thessaloniki
,
Thessaloniki, Hellas
(in Hellenic) (in press)
.
Kessener
P.
Piras
S.
2008
The pressure line of the Aspendos Aqueduct
.
Adalya II
pp.
160
187
.
Kienast
H. J.
1977
Der Tunnel des Eupalinos auf Samos. Architectura, Zeitschrift für Geschichte der Architektur,
pp.
97
116
.
Knauss
J.
Heinrich
B.
Kalcyk
H.
1984
Kopais 1 Die Wasserbauten der Minyer in der Kopais: die älteste Flussregulierung Europas, Institut für Wasserbau und Wassermengenwirtschaft der Technische Universität München, Bericht Nr. 50
,
München
,
Germany
.
Koutsoyiannis
D.
Angelakis
A. N.
2004
Agricultural hydraulic works in ancient Hellas
. In:
The Encyclopaedia of Water Science
(
Stewart
B.A.
Howell
T.
, eds).
CRC Press
,
New York
,
USA
, pp.
415
417
.
Koutsoyiannis
D.
Zarkadoulas
N.
Angelakis
A. N.
Tchobanoglous
G.
2008
Urban water management in ancient Hellas: legacies and Lessons
.
ASCE, Journal of Water Resources Planning & Management
134
(
1
),
45
54
.
Lambrinoudakis
V.
2014
Ancient aqueduct in Naxos
. In:
IWA Regional Symposium on Water, Wastewater and Environment-Traditions and Culture
(
Kalavrouziotis
I. K.
Angelakis
A. N.
, eds).
March 22–24
,
Patras
,
Greece
, pp.
453
459
.
Lazos
C.
1993
Engineering and Technology in Ancient Hellas
.
Aeolos
,
Athens
(in Hellenic)
.
Lolos
Y.
1997
The Hadrian aqueduct of Corinth
.
Hesperia
66
(
2
),
271
314
.
Malacrino
C. G.
2010
Constructing the Ancient World: Architectural Techniques of the Greeks and Romans
.
Getty Publications
,
Los Angeles, California
,
USA
.
Manoledakis
M.
Makri
E.
2008
The Aqueduct of Hortiatis. The Archaeological Work in Macedonian and Thrace
,
22
,
361
368
.
Publ. Ziti
,
Thessaloniki
(in Hellenic)
.
Μarinos
P.
2005
Experiences in tunnelling through karstic rocks
. In:
Proceedings of International Conference CVIJIC 2005: Water resources and environmental problems in Karst
, pp.
617
644
.
Mays
L. W.
Koutsoyiannis
D.
Angelakis
A. N.
2007
A brief history of urban water supply in antiquity
.
Water Science & Technology, Water Supply
7
(
1
),
1
12
.
Nikolic
M.
2008
Cross-Disciplinary Investigation of Ancient Long-Distance Water Pipelines
.
PhD Theses
,
Department of Greek and Roman Studies, University of Victoria
,
Canada
.
Oikonomakis
N. E.
1984
The aqueduct of Lyttos. In: Lyktos, Scientific periodical edition
,
Vol. 1
, pp.
66
99
.
Olson
Å.
2012
How Eupalinos navigated his way through the mountain – An empirical approach to the geometry of Eupalinos
.
Anatolia Antiqua, Institut Français d’Études Anatoliennes
20
,
25
34
.
Ozkaldi
A.
Akbas
H.
Celik
K. B.
2007
Evaluation of historical water works in turkey from hydraulic engineering point of view
. In:
Proc. of International History Seminar on Irrigation and Drainage Tehran-Iran
,
May 2–5, 2007
, pp.
63
72
.
Robinson
B. A.
2011
Histories of Peirene: A Corinthian Fountain in Three Millennia
.
The American School of Classical Studies at Athens, ASCSA
,
54 Souidias Street, GR-106 76
,
Athens
,
Greece
.
Sandstrom
G. E.
1963
The History of Tunnelling
,
Barie and Rockliff
,
London
,
UK
, p.
427
.
Sfeikos
A.
Marinos
P. G.
2004
Behavior of Pindos flysch during tunnelling through a thrust zone. Deformation and rock behavior
. In:
Experience from the Acheloos River diversion tunnel to Thessaly, Proceedings 10th International Congress
,
Thessaloniki
,
April 2004
,
Bulletin of the Geological Society of Greece, XXXVI
, pp.
1843
1852
.
Simmons
W. E.
1887
Aqueducts. The Popular Science Monthly
,
11
, pp.
26
37
.
Skotsimara
G.
Koroniotaki
J.
Pavlitina
N.
Bothou
C.
2008
The water cycle in Athens from ancient times to our days. PDF presentation. http://www.comeniusonline.info/kreis/grcycle.pdf
.
Spanakis
S.
1981
The Water Supply of Iraklion, 828–1939
.
The Technical Chamber of Hellas
,
Iraklion
,
Hellas
(in Hellenic)
.
Stavranides
N.
1969
Article in Patris Newspaper
.
Patris Iraklion newspaper
,
Hellas
16/11/96 (in Hellenic)
.
Symeonoglou
S.
1985
The Topography of Thebes from the Bronze Age to Modern Times
.
Princeton University Press
,
Princeton
,
USA
.
Tassios
Th.
2004
The tunnels of ancient Greeks, TO VIMA (Athens newspaper), 12 December 2004 (in Hellenic)
.
Tassios
Th.
2007
Water supply of ancient Greek cities
.
Water Science and Technology, Water Supply
7
(
1
),
165
172
.
Troll
C.
1963
Qanat-Bewasserung in der Alten und Neuen Welt. Mitteilungen der Osterreichischen Geo-graphischen Gesellschaft
105
, pp.
313
330
.
Tsatsanifos
C.
2007
Ancient Greek Geotechnical Successes
. In:
Presentation during the ISSMGE European Members Meeting during the XIV ECSMGE
,
Madrid
.
Tsatsanifos
C.
Michalis
I.
2014
Tunnelling in Hellas: Past, Present, Future
. In:
Proc. of 2nd Eastern European Tunnelling, Conference Tunnelling in a Challenging Environment Making Tunnelling Business in Difficult Times
.
Athens
,
Hellas
,
28 September–1 October 2014
.
Vavliakis
E.
1989
The Qanat systems in Hellas: A study of Qanat systems in Phyllida of Serres from morphological, hydrographic and socio-economical view
.
Aristotle University of Thessaloniki, Dept. of Geology
,
Thessaloniki
,
Hellas
, p.
93
(in Hellenic)
.
Vavliakis
Ε.
1997
The Qanat systems as basic factors of development of prehistoric and historic civilizations at the Hellenic area
. In:
Proceeding 1st International Conference ‘Ancient Greek Technology’, Thessaloniki
,
4–7 September 1997
, pp.
583
591
.
Vavliakis
E.
Staninos
E.
Stefos
N.
1995
Study of water – collection system of Agia Paraskevi Qanat in Hortiatis of Thessaloniki (North Hellas)
. In:
Proceedings of the 4th Panhellenic Geographical Conference
,
Athens
,
October 12–14, 1995
(in Hellenic)
.
Voudouris
K.
2012
Diachronic evolution of water supply in eastern Mediterranean
. In:
Evolution of water supply through the Millennia
(
Angelakis
A. N.
Mays
L. W.
Koutsoyiannis
D.
Mamassis
N.
, eds).
IWA Publishing
,
London, New York
,
Chapter 4
, pp.
77
89
.
Voudouris
K.
Christodoulakos
Y.
Stiakakis
M.
Angelakis
A. N.
2013
Hydrogeological characteristics of Hellenic aqueducts-like qanats
.
Water
5
,
1326
1345
.
Xanthoudides
S.
1927
Chandax: Iraklion
.
Alexiou Press
,
Iraklion
,
Hellas
(in Hellenic)
.
Zarkadoulas
N.
Koutsoyiannis
D.
Manassis
N.
Angelakis
A. N.
2012
A Brief History of Urban Water Management in Ancient Hellas
. In:
Evolution of Water Supply throughout Millennia
(
Angelakis
A. N.
et al
, eds).
IWA Publishing
,
London
,
UK
,
Chapter 10
, pp.
259
270
.