Troglodyte Canal of Daryoon

The city of Shushtar is indebted to the Karun River for its development, and represents one of the earliest Iranian cities. Established on a sand cliff, the city currently lies several meters above the river level that would have caused difficulties in exploiting water from the river. The problem was dexterously resolved by the local residents through construction of weirs, irrigation canals and flumes. The Karun is divided into two branches of Gargar and Shatit to the north of Shushtar, which join again at Band-e Qir (Bitumen weir) almost 40km south of Shushtar. Bounded by these branches, Shushtar resembles an island with a width of 10 to 15km and ca. 40km length. Almost 300km upstream from Shushter weir, two main and several secondary tunnels have been dug under Salasal Fort, with their mirage lying in the Shatit River not far from divergence point of the river north of Shushtar. After running for 100m, the tunnels confluence creates the open canal of Daryon, which later splits again into two channels at Khak weir in southwest of Shushtar. The first channel flows into the Shatit River at the Arab Hasan weir after running 33km. Lashkar and Shah Ali weirs, near Abdullah mausoleum, and Khak weir have been constructed on the channel in order to manage the water flow. The fact that the Daryon canal is hand cut and artificial is supported both by the references in historical sources and by the fact that the cliffs on which Shushtar lies and the canal was cut through, reveal traces of axes. However, the exact construction date of the canal is more difficult to establish. The Greek historical documents such as those by Herodotus and Xenophon, and the Iranian sources such as those by alTabari and al-Mas’udi demonstrate Shushter as flanked by two tributaries of the Karun. However, they simply mention the Gargar canal or al-Masroqan river (ancient name of the Karun). Some scholars argue that the canal was founded to solve the problems in regards to crossing the river and to direct the water to southern Shushatr plain under Daruis III, thus attributing its origin to the pre-Alexandrian period. They also maintain that as the river got deeper the water failed to flow over the weir, therefore the Shadravan weir was reconstructed or replaced the earlier one during the Sasanian period to allow the water to flow over. Others believe that the Daryoon stream was dried up as a result of destruction of Shadravan weir and attribute the construction date of the canal and its weir to the Sasanian period. The present paper discusses the construction technique of the Daryoon canal from technical aspect and based on archaeological and historical evidence analyzes whether it was constructed earlier or later than or at the same time with the Shadravan weir, Mizan barrage and the troglodyte Gargar canal, which are all hydraulic installations created during the Sasanian period.