The Satluj River () is the longest of the five rivers that flow through the historic crossroads region of Punjab in northern India and Pakistan. The Sutlej River is also known as Satadru. It is the easternmost tributary of the Indus River. The Bhakra Dam is built around the river Sutlej to provide irrigation and other facilities to the states of Punjab, Rajasthan and Haryana.
The waters of the Sutlej are allocated to India under the Indus Waters Treaty between India and Pakistan, and are mostly diverted to irrigation canals in India like the Sirhind Canal, Bhakra Main Line and the Rajasthan canal. The mean annual flow is 14 million acre feet (MAF) (roughly 1.727 × 1013 L) upstream of Ropar barrage, downstream of the Bhakra dam. It has several major hydroelectric points, including the 1,325 MW Bhakra Dam, the 1,000 MW Karcham Wangtoo Hydroelectric Plant, and the 1,500 MW Nathpa Jhakri Dam. The drainage basin in India includes the states and union territories of Himachal Pradesh, Punjab, Ladakh and Haryana.
Course
The source of the Sutlej is west of the catchment area of Lake Rakshastal in Tibet, as springs in an ephemeral stream. Lake Rakshastal used to be part of the Sutlej river basin long ago and separated from the Sutlej due to tectonic activity. The nascent river flows at first west-northwest for about under the Tibetan name Langqên Zangbo (Elephant River or Elephant Spring) to the Shipki La pass, entering India in Himachal Pradesh state. It then has its main knee heading west-southwest for about to meet the Beas River near Harike, Tarn Taran district, Punjab state. Ropar Wetland in Punjab state is located on the Sutlej river basin. Evidence suggests Indus Valley civilisation also flourished here. Ungti Chu and Pare Chu rivers which drain the southeastern part of Ladakh are tributaries of Sutlej river.
Continuing west-southwest, the Sutlej enters Pakistan about east of Bhedian Kalan, Kasur District, Punjab province, continuing southwest to water the ancient and historical former Bahawalpur princely state. Few centuries ago, Sutlej river was merging with the Ghaggar river to discharge in to the Arabian sea. In approx. 1797 BC, the course of the Sutlej river moved towards the north to join the Beas river.
About north of Uch Sharif, the Sutlej unites with the Chenab River, forming the Panjnad River, which finally flows into the Indus river about west of the city of Bahawalpur. The area to the southeast on the Pakistani side of the Indian border is called the Cholistan Desert and, on the Indian side, the Thar Desert.
The Indus then flows through a gorge near Sukkur and the fertile plains region of Sindh, forming a large delta region between the border of Gujarat, India and Pakistan, finally terminating in the Arabian Sea near the port city of Karachi, Pakistan. During floods, Indus river water flows into the Indian part of the Great Rann of Kutch. Thus Gujarat state of India is also a riparian state of the Indus river as the Rann of Kutch area lying west of Kori Creek in the state is part of the Indus River Delta.
Puranic Mention and Etymology
In the Chaitra-Ratha Parva of Adi Parva of Mahābhārata, when sage Vasishṭha wants to commit suicide he saw the river named Haimāvata (whose source is Himavat), flooded and full of crocodiles and other aquatic monsters. So he jumps into the river. The river thinking that Vasishṭha is a mass of unquenchable fire dilated itself and flew in a hundred different directions. Henceforth the river was named śatadra (or śatadru) which means the river of a hundred courses. So, Vasishṭha landed on dry land and was unharmed.
Langqên Zangbo
Langqên Zangbo (; ) is a river in Ngari, Tibet, China. The name Langqên, Tibetan for "elephant", is because of a valley that resembles an elephant trunk. This river is the main source of the Sutlej, a tributary of Indus River. It enters India at Shipki La pass. The source is south of Gangdise Range, in Ngari Prefecture. Its course is mainly in the Zanda County. The river drains an area of 22,760 km2, and covers a length of 309 km. The drop in height is 3,256 m. Historically, the river was the centre of the Zhangzhung Kingdom until its fall in the 8th century AD.
Geology
Sutlej is an antecedent river, which existed before the Himalayas and entrenched itself while they were rising. The Sutlej, along with all of the Punjab rivers, is thought to have drained east into the Ganges prior to 5 mya.