The Biar aqueduct is the most sophisticated of the aqueducts supplying water to Jerusalem during classical periods. It includes the Biar spring, an underground Shaft Tunnel ∼3 km long harvesting groundwater (cuniculus), a dam, a surface channel, and a tunnel traversing a ridge. We conducted a survey of the Biar underground Shaft Tunnel, mapping all of its accessible parts (∼1200 m), facilitating a new understanding of the cutting-edge hydrogeologic and engineering skills used for this project. The last ∼536 m of the Biar Shaft Tunnel was constructed with a unique ashlar channel, divided into segments, designed to withstand different loads: (a) in a mechanically weak bedrock, a channel with arched gables and barrel vault specus was built within a hewn winding tunnel, (b) when dug as an open shallow trench, a channel roofed with complex gables of ashlars with drafted margins was built, and (c) to release hydraulic pressure, a channel roofed with alternations of barrel vaults and simple gables set perpendicular to the course of the tunnel was constructed. 14C dating of plaster samples suggests that the Biar aqueduct was built in the mid-first century CE and renovated in the days of Aelia Capitolina in the second century CE.
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- Biar aqueduct
- Roman Legion
- ancient Jerusalem