The Karun (, ) is the Iranian river with the highest water flow, and its only navigable river. It is long. It rises in the Zard Kuh mountains of the Bakhtiari district in the Zagros Range, receiving many tributaries, such as the Dez and the Kuhrang, before passing through the capital of the Khuzestan Province of Iran, the city of Ahvaz before emptying to its mouth into Arvand Rud (Shatt al-Arab). The Karun continues toward the Persian Gulf, forking into two primary branches on its delta – the Bahmanshir and the Haffar – that join the Arvand Rud, emptying into the Persian Gulf. The important Island of Abadan is located between these two branches of the Karun. The port city of Khorramshahr is divided from the Island of Abadan by the Haffar branch. Juris Zarins and other scholars have identified the Karun as one of the four rivers of Eden, the others being the Tigris, the Euphrates, and either the Wadi al-Batin or the Karkheh. Name In early classical times, the Karun was known as the Pasitigris. The modern medieval and modern name, Karun, is a corruption of the name Kuhrang, which is still maintained by one of the two primary tributaries of the Karun. J. G. Lorimer also records in his Gazetteer of the Persian Gulf, Oman and Central Arabia that it was known by the name "Dujail," which could be translated "Little Tigris," to medieval Arab and Persian geographers. Course It originates in the Zagros Mountains of western Iran, on the slopes of Zard-Kuh. The river flows south and west through several prominent mountain ridges and receives additional water from the Vanak on the south bank and the Bazoft on the north. These tributaries add to the catchment of the river above the Karun-4 Dam. downstream, the Karun widens into the reservoir formed by the Karun-3 Dam. The Khersan flows into an arm of the reservoir from the southeast. The river passes through this reservoir and flows through a narrow canyon, now in a northwest direction, past Izeh, eventually winding into the Sussan Plain. The Karun then turns north into the reservoir of Shahid Abbaspour Dam (Karun-1), which floods the river's defile to the southwest. The Karun flows southwest into the impoundment of Masjed Soleyman Dam (Karun-2), then turns northwest. Finally, it leaves the foothills and flows south past Shushtar and its confluence with the Dez. It then