The valens aqueduct of constantinople: hydrology and hydraulics
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The valens aqueduct of constantinople: hydrology and hydraulics Martin Crapper1 Received: 5 May 2020 / Accepted: 21 August 2020 © The Author(s) 2020
Abstract A hydrological and hydraulic engineering analysis has been carried out on the Valens aqueduct system constructed from around AD 345 and serving Constantinople. A GIS analysis of previous field observations combined with a digital elevation model confirmed the aqueduct’s likely route and slope. Macrophysical Climate Modelling revealed that contemporary weather data was an appropriate proxy for the time of the aqueduct’s construction, and modern flow data was obtained for some of the springs that fed the aqueduct. Existing, previously documented remains, especially at intakes, were considered, and the industry standard software HEC–RAS was used to simulate the performance of the aqueduct system with a view to understanding the amount of water it could have delivered to the city, the seasonal variation in supply and the most likely configuration of the aqueduct, where this was not clear from existing archaeology. It was concluded that the most likely configuration for the aqueduct system was a fourth and a fifth century channel continuing separately and in parallel to the city walls, which might have delivered flow the range of 0.73 m3/s in the driest month of October to 1.73 m 3/s in the wettest month of March over an average year. Keywords Roman · Aqueduct · Constantinople · Hydrology · Hydraulics · Simulation
Introduction and background The modern visitor to Istanbul sees a 971 m long aqueduct bridge commonly referred to as the Valens Aqueduct. In fact this bridge, impressive though it is, is just one small part of a water supply system stretching hundreds of kilometres into the Thracian forest, bringing water to the city that was the capital of the Roman Empire from AD 330. Contemporary sources attest to the lack of water, Themistius Oratio XIII noting the city “afficted with thirst and drought and not far from vanishing…”. In response to what was apparently a seasonal problem, major aqueduct construction took place from around 340 to 373 (the fourth century line), with a further very significant extension around fifty years later (the * Martin Crapper [email protected] 1
Department of Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, UK
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Fig. 1 Plan of the Valens aqueduct system showing fourth and fifth century lines and locations of main spring sources and catchments
fifth century line) (Crow et al. 2008a, b). Despite its length and importance, the system was very little considered by classical archaeologists until Çeçen (1996) and Crow et al. (2008a, b). This latter study gave rise to a solid understanding of the arrangement of the system, which is shown in Fig. 1. The fourth century line has two main sources, at Danamandıra (where the Kaynarca and Papu springs were adjacent) and at Pinarca, with the two branches merging into a single channel near
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