The Karun is the Iranian river with the highest water flow, and the country's only navigable river. It is 950 km (590 mi) long. The Karun rises in the Zard Kuh mountains of the Bakhtiari district in the Zagros Range, receiving many tributaries, such as the Dez and the Kuhrang. It passes through the city of Ahvaz, the capital of the Khuzestan Province of Iran, before emptying to its mouth into Arvand Rud.