KARUN, an important river of Persia. Its head-waters are in the mountain cluster known since at least the 14th century as Zardeh Kuh (13,00o ft.), and situated in the Bakhtiari country about i oo miles W. of Isfahan. In its upper course, until it emerges from the hills above Shushter it is called Ab-i-Kurang.
From the junction of the two principal sources in the Zardeh Kuh at an altitude of about 8,000 ft., the Ab-i-Kurang is a power ful stream, full, deep, and flowing with great velocity for most of its upper course between precipices varying in height from I,000 to 3,00o ft. The steepness and height of its banks here make it useless for local irrigation purposes. From its principal sources to Shushter the distance as the crow flies is only about 75 m., but the course of the river is so tortuous that it travels 250 M. before it reaches that town.
Besides being fed on its journey through the Bakhtiyal country by many mountain streams, it receives several tributaries, the most important being the Ab-i-Bazuft from the right and the Ab-i-Bar from the left. At Shushter it divides into two streams, one the Ab-i-Gargar, a channel, in part artificial, cut in olden times and flowing east of the town; the other, and main stream, the Ab-i-Shatait, flowing west. The two streams unite, after a run of about 5o m. at Band-i-Qir, 24 m. S. of Shushter, where the Ab-i-Diz (river of Dizful) also comes in, on the right bank.
From Band-i-Kir to a point two miles above Mohammerah the river is called Karun and is navigable from thence to its mouth except for a distance of about 2 miles just below Ahwaz, where a series of cliffs and rocky shelves cross the river and cause rapids. Between Ahwaz and Band-i-Qir (46 m. by river 24 m. by road) the river has an average depth of about 20 ft., but below Ahwaz down to a point a few miles above Mohammerah it is in places very shallow and in the summer vessels with a draught exceeding 3 ft. are liable to ground. About 12 miles above Mohammerah and branching off to the left, is a choked-up river bed called the "Blind Karun," by which the Karun found its way past Qubban to the sea, until about 1766. Ten miles lower down a channel called the Bahmishir takes off from the left bank and flows south ward. It is navigable to the sea for small craft. The main river, here about a quarter of a mile broad and 20 to 3o ft. deep, now flows west and after passing Mohammerah enters the Shatt-al Arab about 20 m. below Basra.
This part of the river, from the Bahmishir to the Shatt, is a little over 3 m. in length, and as its name Hafar (dug) implies,
is an artificial channel. We learn from the Arab geographer Muqaddasi (A.D. 986) that it was dug about A.D. 980 to facilitate water communication between Ahwaz and Basra. The total length of the Karun is 46o to 470 m. while the distance from its sources to its junction with the Shatt is only 16o m. as the crow flies. The Karun up to Ahwaz was opened to international navigation on Oct. 3o, 1888, and Messrs. Lynch of London established a fort nightly steamer service on it immediately afterwards. River steamers now ply between Mohammerah and Nasiri and there is a daily service of motor bellums to Ahwaz. A boat of the Meso potamia Persia Corporation runs four times a month from Ahwaz to Shalili and back, and one of the Nasiri Company three times. The shipping on the lower Karun has in the last few years become increasingly important, on account of the activities of the Anglo Persian Oil Co.'s Oil Fields in south-west Persia.