Sefid-Rud

Other names and transcriptions include Sepīd-Rūd, Sefidrud, Sefidrood, Sepidrood, and Sepidrud. Above Manjil, "Long Red River".^[1][2]

William Smith equated the river with the Amardus (Ancient Greek: Ἀμάρδος) or Mardus (Μάρδος) river of antiquity.^[3][4]

The river is historically famous for its abundant fish, especially the Caspian trout, Salmo trutta caspius.^[5]

The Sefid-Rud has cut a water gap through the Alborz mountain range, the Manjil gap,^[6] capturing its two headwater tributaries, the Qizil Üzan and Shahrood rivers. It then widens the valley between the Talesh Hills and the main Alborz range. The gap provides a major route between Tehran and Gīlān Province with its Caspian lowlands.^[6]

In the wide valley before the Sefid-Rud enters the Caspian Sea, a number of transportation and irrigation canals have been cut; the two biggest are the Khomam and the Now.^[7]

Dam and reservoir

The Sefid-Rud was dammed in 1962 by the Shahbanu Farah Dam (later renamed Manjil Dam),^[8] which created a 1.86 cubic kilometres (0.45 cu mi) reservoir and allowed the irrigation of an additional 2,380 km² (919 sq mi).^[8] The reservoir mediates some flooding and significantly increased rice production in the Sefid Rud delta.^[9][10] The hydroelectric component of the dam generates 87,000 kilowatts.^[8] The completion of the dam had a negative impact on the river's fisheries, through reduced stream flow (due to diversion), increased water temperature, and decreased food availability, especially for sturgeon but also for the Caspian trout.^[11]

The river was known in antiquity as Mardos (Greek: Μαρδος; Latin: Mardus) and Amardos (Greek: Αμαρδος; Latin: Amardus).^[2] In the Hellenistic period, the north side of the Sefid (then Mardus) was occupied by the Cadusii mountain tribe .^[12]

David Rohl proposes identification of Sefid-Rud with the Biblical Pishon river.^{[citation needed]}