Indus (ĭnˈdəs) [key], chief river of Pakistan, c.1,900 mi (3,060 km) long, rising in the Kailas range in the Tibetan Himalayas, and flowing W across Jammu and Kashmir, India, then SW through Pakistan to the Arabian Sea SE of Karachi. The upper Indus, fed by snow and glacial meltwater from the Karakorum, Hindu Kush, and Himalayan mts., flows through deep gorges and scenic valleys. The turbulence of its rushing waters makes it unsuitable for navigation.
The Indus then flows onto the dry Punjab plains of Pakistan and becomes a broad, slow-moving, silt-laden stream. There it receives the combined waters of the five rivers of the Punjab (Jhelum, Chenab, Ravi, Beas, and Sutlej), its chief affluent. In Pakistan the Indus is extensively used for irrigation and hydroelectric-power generation. The Jinnah, Sukker, and Kotri barrages feed the main Indus canals in W Punjab and Sind. The irrigated plain is Pakistan's most densely populated region and its main agricultural area; wheat, corn, rice, millet, dates, and fruits are the chief crops.
The lower Indus is navigable for small boats but is little used for transportation, at least since the development of railroads. The extensive use of the Indus's waters for irrigation has greatly reduced the flow of freshwater in the lower Indus, leading to the encroachment of saltwater up the lower river and the loss to the Sind of millions of acres of surrounding farmland to the sea or salt and of hundreds of thousands of acres of ecologically important mangrove swamp.
The river valley was the site of the prehistoric Indus valley civilization, and the Indus was once considered to be the western boundary of India. The use of the Indus and its tributaries has been a source of conflict between Pakistan and India, although a treaty by which the waters were to be shared was signed in 1960; the use of the river system's waters also is an issue between the provinces of Punjab and Sind within Pakistan.