|Provinces||Chaharmahal and Bakhtiari, Khuzestan|
|Cities||Shushtar, Ahwāz, Khorramshahr|
|- location||Zagros, Khuzestan|
|Mouth||Arvand Rud / Shatt al-Arab|
|- elevation||0 m (0 ft)|
|Length||950 km (590 mi)|
|Basin||65,230 km2 (25,185 sq mi)|
|- average||575 m3/s (20,306 cu ft/s)|
|- max||2,995 m3/s (105,767 cu ft/s) |
|- min||26 m3/s (918 cu ft/s) |
The Kārun (also spelled as Karoun) is Iran's most effluent, and the only navigable, river. It is 450 miles (720 km) 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 Ahwaz.
The Karun continues toward the Persian Gulf, forking into two primary branches on its delta: the Bahmanshir and the Haffar that joins the Shatt al-Arab (Arvand Rud in Persian), 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.
In the Biblical tradition, Karun is to be identified with Pishon, one of the four rivers of Eden/Paradise. The others being Tigris, Euphrates and the Karkheh ("Gihon" of the Biblical story). In the early classical times, Karun was known as the Pasitigris, which may be pointing etymologically to the source of the Biblical name, Pishon. 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.
It originates in the Zagros Mountains of western Iran, on the slopes of 14,921-foot (4,548 m) 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 Bazuft on the north. These tributaries add to the catchment of the river above the Karun-4 Dam. Downstream 25 kilometres (16 mi), 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 bends southwest and bisects the city of Ahvaz, and south through farmland to its mouth on the Shatt Al-Arab river at Khorramshahr, where its water, together with that of the Tigris and Euphrates, turns sharply southwest to flow to the Persian Gulf.
The largest river by discharge in Iran, the Karun River's watershed covers 65,230 square kilometres (25,190 sq mi) in parts of two Iranian provinces. The river is around 950 kilometres (590 mi) long and has an average discharge of 575 cubic metres per second (20,300 cu ft/s). The largest city on the river is Ahvaz, with over 1.3 million inhabitants. Other important cities include Shushtar, Khorramshahr (a port), Masjed-Soleyman, and Izeh.
Much of Khuzestan's transport and resources are connected in one way or another to the Karun. Since the British first discovered oil at Masjed-Soleyman, the Karun has been an important route for the transport of petroleum to the Persian Gulf, and remains an important commercial waterway. Water from the Karun provides irrigation to over 280,000 hectares (690,000 acres) of the surrounding plain and a further 100,000 hectares (250,000 acres) are planned to receive water.
The Karun River valley was once inhabited by the Elamite civilization which rose about 2,700 B.C. In several points in history, Mesopotamian civilizations such as Ur and Babylon overthrew the Elamites and gained control of the Karun and its surroundings in modern Khuzestan. However, the Elam empire lasted until about 640 B.C., when the Assyrians overran it. The city of Susa, near the modern city of Shush between the Dez and Karkheh rivers, was one of their largest before it was destroyed by the invaders.
The first known major bridge across the river was built by the Roman captives that included its emperor Valerian, whence the name of the bridge and dam Band-e Kaisar, "Caesar's dam"—at Shushtar (3rd century AD).
In two of several competing theories about the origins and location of the Garden of Eden the Karun is presumed to be the Gihon River that is described in the Biblical book of Genesis. The strongest of these theories propounded by archaeologist Juris Zarins places the Garden of Eden at the northern tip of the Persian Gulf, fed by the four rivers Tigris, Euphrates, Gihon Karun and Pishon (Wadi Al-Batin).
The name of the river is derived from the mountain peak, Kuhrang, that serves as its source.
Famous silent film documentary Grass: A Nation's Battle for Life (1925) tells the story of Bakhtiari tribe crossing this river with 50,000 people and 500,000 animals.
It was here during the Iran–Iraq War that the Iranians stopped the early Iraqi advance. With its limited military stocks, Iran unveiled its "human wave" assaults which used thousands of Basij (Popular Mobilization Army or People's Army) volunteers.
In September 2009, three districts of Basra province in southern Iraq were declared disaster areas as a result of Iran's construction of new dams on the Karun. The new dams resulted in high levels of salinity in the Shatt Al-Arab, which destroyed farm areas and threatened livestock. Civilians in the area were forced to evacuate.
There are a number of dams on the Karun River, mainly built to generate hydroelectric power and provide flood control. Gotvand Dam, Masjed Soleyman Dam, Karun-1 (Shahid Abbaspour Dam), Karun-3, and Karun-4, most owned by Iran Water and Power Resources Development Co., all are on the main stem. Karun-2 would potentially be located in the Sussan Plain between Shahid Abbaspour and Karun-3, but because of fear of submerging archaeological sites, the project is still under consideration. A Karun-5 dam upstream of Karun-4 has also been proposed. The Masjed Soleyman, Shahid Abbaspour, and Karun-3 dams each generate 1,000-2,000 MW of power to service the peaking power sector of Iran's electricity grid, and when completed, Karun-4 will also generate 1,000 MW. There are also many dams on the river's tributaries. Dez Dam, Bakhtiari Dam (under construction) and Khersan-3 Dam (under construction) are among them. Proposed are Khersan 1, Khersan 2, Zalaki, Liro, Roudbar Lorestan, Bazoft, and others. The dams on the Karun have had a significant effect on the sediment transport and the ecology of the river, and have required the relocation of thousands of residents.
- "Karun River at Ahvaz". River Discharge Database. Center for Sustainability and the Global Environment. 1965-1984. Retrieved 2010-03-15.
- "Regional generalization of flood characteristics in Karun River basin". Flow Regimes from international Experimental and Network Data. International Association of Hydrological Sciences. 1994. Retrieved 2010-03-14.
- "Karun River". Encyclopædia Britannica. Universitat de València. Retrieved 2010-03-14.
- "Province of Khuzestan". Cities/Provinces of Iran. Iran Chamber Society. Retrieved 2010-03-15.
- Sadeghian, M.S.; Hassunizadeh, H.; McNaughton, A.N. (2003). Brebbia, C.A., ed. River basin management II—Optimizing the River Karun system, Iran. WIT Press. pp. 109–117. ISBN 1-85312-966-6. Retrieved 2010-03-15.
- "Study and Executive Projects of Irrigation and Drainage Networks". Water Department. Khuzestan Water and Power Authority. Retrieved 2010-03-15.
- Shahmiri, Cyrus. "Elamite Empire". History of Iran. Iran Chamber Society. Retrieved 2010-03-14.
- "And the name of the second river is Gihon: the same is it that compasseth the whole land of Cush." (Genesis, 2:13)
- "Basra province incapable of responding to crisis". Homepage.eircom.net. 2009-09-08. Retrieved 2009-09-08.
- "Karun-2 Dam continues tragedy of cultural destruction at ancient Izeh". Archaeonews. 2006-09-19. Retrieved 2010-03-14.
- Masjed Soleiman Project. Karun & Dez Development Exploitation (Map). Cartography by Iran Water & Power Resources Development Co.. http://en.iwpco.ir/MasjedSoleiman/Lists/Intro/Attachments/1/Intro03.jpg. Retrieved 2010-03-14.
- "Masjed Soleiman Project: Technical Info". Masjed Soleiman Project. Iran Water and Power Resources Development Co. Retrieved 2010-03-14.
- "Karun 3 Project: Technical Info". Karun 3 Project. Iran Water and Power Resources Development Co. Retrieved 2010-03-14.
- "Karun 4 Project: Technical Info". Karun 4 Project. Iran Water and Power Resources Development Co. Retrieved 2010-03-14.
- Karun-3, Dam and Hydroelectric Power Plant, History.
- N. Jafarzadeh, S. Rostami, K. Sepehrfar, and A. Lahijanzadeh, Identification of the Water Pollutant Industries in Khuzastan Province, Iranian Journal of Environmental Health Science & Engineering, Vol. 1, No. 2, pp. 36–42 (2004). 
- Pasitigris (Karun), Photos from Iran, Livius.
- Karun river marshes, Factsheet, BirdLife International.
- Karun-3, Dam and Hydroelectric Power Plant, Home. Album.
- Map on Encarta