With a length of 890 km, Karun is the longest, the only navigable and most plentiful river in Iran which divides Ahvaz into eastern and western slices. It originates from the Zard Kuh-e Bakhtiari of Zagros range and trespasses the Khuzestan plain. In the north of Shushtar, Karun River bifurcates in two separate streams that eventually rejoin in the south of Shushtar. Dez River is the most important branch of the Karun River. Karun meets Arvand River in Khorramshahr, making Iran-Iraq border before outpouring to the Persian Gulf. Since the Reza Shah Pahlavi regimen, nine bridges of different designs have been constructed on Karun River; among the most prominent there are Pol-e Siah or Black Bridge (the first bridge of Ahvaz), Pol-e Sefid or White Bridge (the earliest Iranian suspension bridge), Pol-e Gofteguy-e Tamadonha or Ali Ibn Mahzyar Bridge, Cable-stayed Bridge or Pol-e A, and Pol-e Tabiat or Nature Bridge (for pedestrians only).
