3. Karkheh – 559 miles
Iranian rivers have been used to provide a wealth of agricultural benefits to civilisation since the ancient times. More modern dams in Iran are used to provide even large agricultural benefits as well as generate hydroelectricity for organisations such as steel companies, power plants and oil refineries. The only permanently navigable waterway in Iran is the Karun River, which has been an essential commercial waterway since oil was discovered within the regions surrounding it. Other rivers that are considered as very important trade routes are the Sefid Rud River, for it’s quantity of fish and the Diyala River Valleys.