Dara Dam

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The Dara Dam was a Roman arch dam in Dara in Mesopotamia ( present-day south-eastern Turkey ) and one of the few examples of this type of dam in the pre-modern. The current location of the dam is uncertain, but could point more to the common type of a gravity dam.

Ancient tradition

The construction of the dam was the Eastern Roman historian Procopius in his treatise on the architectural achievements of the era of Justinian I ( De Aedificiis 2.3. ) Survived. His report is from technology perspective of the history of particular interest: first, a clear understanding of the operating principle of an arch dam can be seen, which differs greatly from the beyond usual in ancient times and gravity dam.

Prokop highlights two essential Funktionsprinzpien features: first, that the dam had an arc- shaped plan in order to withstand the water pressure so better, and not merely because the bedrock there offered the best building. And, secondly, that the dam the flow is not defied by its sheer weight, as is the case for gravity dams, but by the derivative of the pressure forces of the abutments on the side walls of the canyon, which is made possible by the curvature of the underlying arc.

Another known from antiquity arch dam stood at Glanum in France.

Modern exploration

A local exploration in the late 1980s by the German scientist Gunther Garbrecht has raised the question of whether there really was an arch dam on the dam described by Procopius. Garbrecht could make a site just in front of the ancient city walls, locate matches in its essential features with Prokop precise description - with the exception of the arc- shaped plan of the dam.

The dam discovered, about a 4 m high and 5 m thick ashlar wall with a Roman concrete core, has an estimated crest length of 180-190 m; the central portion is completely destroyed at a length of 60-70 m. While it is not inconceivable that the dam once took a curved course in the area of ​​the wall duct, but the wing walls obtained suggest rather to a polygonal floor plan. This would mean that the dam of Dara withstood the water pressure by its own weight and not by bow effect. Garbrecht expresses the assumption that the irregular shape of the dam Prokop could have inspired a poetic allusion to the crescent-shaped firmament. Restrictive, however it should be noted that his observations on the ground not meet the requirements of systematic hydrological and topographical studies corresponded to which he sends a reminder in the face of creeping destruction of the ancient site.