Valley Crossings and Flood Management for Ancient Roman Aqueduct Bridges

Abstract

Calculation of stormwater flow passage underneath two ancient Roman bridges supporting an aqueduct in southern France provides insight into the Roman engineers’ design of aqueduct bridges. The bridges are quite different although the watersheds they cross have similar characteristics. At a height of 5.4 m (18 ft), the Simian Bridge has four arches while the Charmassone Bridge [height of 2 m (7 ft)] has a culvert to pass stormwater flows. The Simian Bridge was designed to maintain the needed elevation across the valley by use of arches, and it easily passes flood flows. In contrast, the Charmassone Bridge may have been designed to manage flood flows as evidenced by the sizing of its culvert and use of buttressing to support upstream hydrostatic pressures due to stormwater retention behind the bridge.