Roman aqueduct Liestal - Augusta Raurica
The Roman aqueduct Liestal - Augusta Raurica is a 6.5 kilometer long, underground Roman aqueduct , of which numerous sections have been excavated and examined.
Purpose of the structure
The aqueduct served as the main water supply for the Roman colony town of Augusta Raurica . In the border area between today's municipalities of Liestal and Lausen , the water of the Ergolz was dammed, collected and drained on its right side. In the southern urban area of Augusta Raurica, the line ended in a moated castle that had not yet been found . The water was then presumably guided into cisterns via an above-ground aqueduct , the supporting pillars of which could be located, and mostly distributed via wooden pipes to the fountains, baths and private houses in the city. The capacity of the line was around 300 liters per second, so 24,000 cubic meters of water flowed to Augusta Raurica per day. Even assuming a leakage loss, around 20,000 cubic meters remain. With an estimated 20,000 inhabitants at the height of the city, each inhabitant had 1000 liters of water per day. Vitruvius gives information on how the water was distributed in Roman cities: Priority was given to public fountains that were set up at intervals of no more than 100 meters. Thereafter, the thermal baths - available in practically every Roman city - then the private households. The running wells also fed the sewage system: unused water flowed into underground pipes on which the toilets stood.
Construction
Construction of the “longest Roman structure in Switzerland” is scheduled for the early 1st century, and it was probably used until the 3rd century, the time of the decline of the old colony city. There are no text sources for this. The 90 cm wide canal is an extraordinary testimony to Roman engineering and construction . The line has a constant gradient of 1.5 per mille over its entire length. The construction scheme is the same throughout: First a ditch was filled with rubble stones and mortar poured over it. The 135 cm high cheek walls were erected on this approximately 40 cm thick foundation. The conclusion is a barrel vault that was built on a falsework . The interior was mortared watertight up to at least halfway. The mortar, called opus caementitium , was mixed with just a little water from bricks (as a substitute for the classic pozzolan , which is not present here ), moist sand and quicklime . This resulted in an absolutely watertight mortar with special properties: The compound not only had properties comparable to modern Portland cement , but was also able to convert the existing unslaked lime into calcite through running water , which automatically closed small cracks in the structure. Finally, the side walls were filled in with rubble stones up to the top of the vault and the whole thing covered with earth. The more than 50 sections discovered and partially researched to date also showed side feeders and openings in the vault that were walled up afterwards, which were either necessary during the interior work or during maintenance work. The sections have been preserved to varying degrees, as some of the terrain apparently already slipped during the construction period.
Historical perception
In some places the line came to light later and was known to the population. In 1580, the Basel chronicler Christian Wurstisen mentioned in his Basel Chronicle "the very long vault [...] which is inside man's height" and "was certainly also a Roman work". The building erected by the Romans - from a Christian point of view, pagans - also led to the Liestal quarter name “Heidenloch”, which was first mentioned in 1329. A section of the water pipe 70 meters in length is still accessible and walkable there today. There are numerous characters on the walls in this section. Most of them date from the 17th and 18th centuries and were applied with charcoal, chalk, red chalk and pencil, rarely scratched. Often there are initials with year numbers (these range from 1621 to 1927). This “cultural asset” was recorded and documented separately by Baselland Archeology .
Excavations
A section of the route in the Liestal Heidenloch district was particularly well known. The first excavation took place there in 1898. Also in this section, in 1957, on the 2000th anniversary of the city of Basel, a piece of the line about 1.5 meters was cut out and brought to Augst , as this place is considered the cradle of the city of Basel. It is there to this day at the Roman Museum . The opening was converted into an entrance to the section of the line that can be walked on there. A large section of 120 meters in the immediate vicinity was thoroughly explored in 1971/72 when a hillside settlement was built there. Since further sections were or are still in construction areas, parts of it could be explored again and again through emergency excavations (for example in Liestal for new buildings in 1987 on a neighboring parcel in 2012 and on the occasion of an expansion of the cemetery in Füllinsdorf in 2002). This process gradually resulted in a very precise picture of the line, especially the constant build quality and execution.
literature
- Jürg Ewald, Martin Hartmann, Philippe Rentzel: The Roman aqueduct from Liestal to Augst. In: Archeology and Museum 36, Liestal 1997
- Jürg Ewald: The Roman aqueduct from Liestal to Augst. In: Jürg Ewald / Jürg Tauber (Ed.): Tatort Past. Results from archeology today. Opinio Verlag, Basel 1998, ISBN 978-3-909164-62-2 , pp. 211-220
Web links
- The Heidenloch - the longest Roman building in Switzerland on archäologie.bl.ch. Retrieved June 9, 2014.
- Information board about the water supply and annual reports as PDF files on the same page
Individual evidence
- ↑ Archeology Baselland: Annual Report 2012 , Liestal 2013: pp. 38–41.
- ↑ Archeology Baselland: Annual Report 2012 , Liestal 2013: pp. 42–47.
Coordinates: 47 ° 28 ′ 55 " N , 7 ° 44 ′ 56" E ; CH1903: six hundred and twenty-three thousand three hundred ninety-two / 259,072