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LONG DISTANCE AQUEDUCT
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The
Water Supply of Constantinople: Ballıgerme-Kalfaköy section
The Two Systems
Most of our fieldwork
has been focused on the water system in the vicinity of Anastasian Wall
where the existence of two substanial parallel channels has been discovered,
separated by over 6m in altitude near Kurşunlugerme, but gradually converging
further east. The low-level channel is generally 2.4m high and 1.6m wide.
The high-level channel is a narrower guage, at 0.60m wide with a height
of 1m. Both types of channel were constructed by 'cut and cover' techniques
and were roofed with rough stone vaults. In places the hydraulic lime-mortar
lining of the sides of the channels survive with later accretions of distinctive
travertine or sinter deposits. Both the hydraulic mortar plastering and
the channel masonry is usually made of metamorphic or limestone blocks.
From
our investigations we believe that the 4th-century "Valens"
system was more likely to be the "high-level" narrow channel.
The low-level broad channel was therefore built as a massive supplement
to the system, probably in the 5th or 6th centuries. At this time,
new bridges were built in many valleys in order to carry the lower level
channel. In some cases (Büyükgerme, Kumalıdere) the lower elevation enabled
the new channel to adopt a different, shorter, route from the original
channel. In other places (Kurşunlugerme) it is clear that the new aqueduct
bridge carried both the low-level and high-level channel, while the original
bridge was abandoned.
The
main source for this high-level system has been located around Papuç
and Danamandıra in the Mandara Dere, where a large cave and spring have
been located and two separate supply channels survive along the side of
the valley above the river. Further along the parallel lines in the Kurşunlugerme
valley it is possible to observe the high-level channel running at about
6.45m above the lower main line and crossing the valley on a remarkably
well preserved aqueduct, which was built across the top of the lower channel.
The fragmentary remains of an earlier aqueduct for the lower channel still
survive to the east. Evidence suggests that the Vize-Balligerme section
was also originally a narrow channel, but based on our current working
hypothesis, this seems to have been replaced by the later wider channel.
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