The Subansiri (Chayul Chu in Tibet) is a trans-Himalayan river and a tributary of the Brahmaputra River that flows through Tibet's Lhuntse County in the Shannan Prefecture in Southwestern China, and the Indian states of Arunachal Pradesh and Assam. The Subansiri is approximately long, with a drainage basin . It is the largest tributary of the Brahmaputra contributing 7.92% of the Brahmaputra's total flow.

Etymology The name Subansiri is generally connected with the Sanskrit svarṇa ('gold'), reflecting the historical occurrence and extraction of placer gold from the river.

In medieval geographical sources, the river has been identified with Suvarṇaśrī, Svarṇadī and Svarṇanadī, names glossed as the 'river of gold'. Medieval Sanskrit sources preserve gold-associated names that have been identified with the Subansiri. The Kalika Purana refers to a river called Suvarṇaśrī, whose waters are described as carrying particles of gold and which is consequently called svarṇavahā ("gold-bearing"); this river has been identified with the Subansiri. Nityananda Gogoi identifies the Svarṇadī and Svarṇanadī of the Yoginī Tantra with the Subansiri. The text uses Svarṇanadī as the eastern boundary of Madhyapīṭha and, a few verses later, Svarṇadī as the western boundary of Saumārapīṭha. The earlier Ghilamara copper-plate grant of Chutia king Lakshminarayan, dated 1401, similarly records a river named Svarṇadī as the eastern boundary of the donated village of Bakhana; this river has also been identified by historians with the Subansiri.

Originally, the name Subansiri applied to the river only after the confluence of the Chayul Chu and Tsari Chu rivers at Gelensiniak. In early maps of independent India, Tsari Chu was marked as the main Subansiri river. However, over time, the name has been transferred to Chayul Chu, which is called "Upper Subansiri". Within Tibet, the rivers are named after the locations they flow from, such as Loro Chu, Nye Chu, Char Chu and Chayul Chu, all of which apply to the Upper Subansiri or its tributaries.

In the Mising language, the river is called Obonori. This name is distinct from the Sanskrit-derived Subansiri and has its roots in the indigenous Tani language. Obonori reflects the community's connection with the river, which is central to their culture and economy.

History Medieval period The Subansiri valley lay within the principal territorial zone of the Chutia kingdom. D. Nath describes the Chutia territory as being concentrated principally in the river valleys of the Subansiri, Brahmaputra, Lohit and Dihing, with comparatively limited extension into the surrounding hills. Epigraphic evidence records Chutia royal activity in the wider Habung–Lakhimpur region from at least the late fourteenth and early fifteenth centuries. A copper-plate grant issued by the Chutia king Lakshminarayana in 1401, discovered at Ghilamara, records the grant of the village of Bakhana, whose eastern boundary was a river called Svarṇadī. Sarbeswar Barua and Nityananda Gogoi identify this river with the Subansiri.

The lower Subansiri valley formed part of the historical Habung–Lakhimpur region. In his 1800 geographical account of Assam, John Peter Wade described the river as the "Khobunkhiri, or Sobunsiri" and recorded that, after flowing through the north-bank country, it met the Brahmaputra at Habung. Maheswar Neog similarly described the medieval province of Habung as the "Subansiri region" of the then North Lakhimpur district. Chutia authority in this region is independently attested by the Sadiya–Chepakhowa copper-plate grant of 1428, which refers to Vṛhatpatra as the Habung-adhipati, or governor of Habung. In 1512, the Ahom king Suhungmung occupied Panbari in Habung as part of his expansion into the region, beginning a series of conflicts with the Chutia kingdom.

Chutia power was temporarily restored in parts of the disputed tract during renewed fighting in 1520, and a copper plate of the Chutia king Dhirnarayan dated 1522, found in the Dhakuakhana region, records another royal land grant shortly before the final Ahom conquest of the kingdom in 1523–24. Following the annexation, Habung was incorporated into the expanding Ahom administrative system.

The Subansiri later became an important political boundary. Under the Treaty of Majuli of 1563, following the Koch invasion of the Ahom kingdom, the north-bank territory west of the Subansiri was ceded to the Koch kingdom, making the river the boundary between Koch and Ahom-controlled territories on the north bank.

Modern period

The 1950 Assam–Tibet earthquake caused landslides blocking the flow of the Subansiri at Gerukamukh. After three days, the blockade broke, causing a massive flash flood. Over the years, flooding of the river has caused loss of livelihood and life. The 1950 Assam–Tibet earthquake caused landslides blocking the flow of Subansiri at Gerukamukh. After three days, the blockade broke, causing a massive flash flood. Over the years, flooding of the river has caused loss of livelihood and life.

Course Chayul Chu Chayul Chu is formed near Chayul Dzong with the merger of Nye Chu and Loro Chu.

Nye Chu originates in the Tsome County where it is called Sikung. After entering the Lhuntse County, it is called Nyel Chu or Lhuntse Shung Chu. Its valley, called Nyelto, includes important towns such as Ritang and Kyitang, the latter the capital of Lhuntse County. It flows for about 100 km before reaching Chayul Dzong.

Loro Chu is formed by the merger of two headwaters: Loro Karpo Chu (or the "White Loro River") and Loro Nakpo Chu (or the "Black Loro River"). Both rivers originate in the Tsona County, marked by passes that divide the waters of Subansiri from those of Tsona Chu. The two head streams merge near the town of Trathong. The combined river flows for about 40 km before reaching Chayul Dzong.

Chayul Chu flows for about 50 km in Tibet before entering Arunachal Pradesh near the town of Taksing. Before this, it is joined by Char Chu near the village of Lung, and Yume Chu just before entering Arunachal Pradesh.

Subansiri It enters India near the town of Taksing and flows east and southeast through Miri Hills, then south to the Assam Valley at Dulangmukh in Dhemaji district, where it joins the Brahmaputra River at Jamurighat in Lakhimpur district. Small tributaries of the Subansiri include Rangandi, Dikrong and Kamle.

The Subansiri lends its name to two districts in Arunachal Pradesh: Upper Subansiri and Lower Subansiri.

The observed discharge of Subansiri is a maximum of , and minimum of . It contributes 7.92% of the Brahmaputra's total flow.

Tributaries Char Chu

Tsari Chu

Tsari Chu (, "Lo River"; known as Lensi River in Arunachal Pradesh)Satellite images show Chinese building infrastructures in Arunachal, The Arunachal Times, 19 January 2021. rises near the village of Chosam in Tibet and flows east for about 25 miles till the town of Migyitun, where it turns south. It merges with the Subansiri at Gelensiniak. The district of Tsari, consisting of the Tsari Chu valley and its vicinity, is considered holy ground by the Tibetans. No animals are killed and no food is grown in these areas, with the exception of Migyitun. The holiness comes from the Dakpa Sheri mountain peak at the centre of the Tsari district, considered the home of the Buddhist Tantric deity Demchok (Chakrasamvara) and his consort Dorje Phagmo (Vajravārāhī). The pious Tibetans used to carry out a wide circumabulation (called rongkor or "ravine circuit") around the mountain once every 12 years, during the monkey year. They traversed the valley of the Tsari Chu river until its junction with Subansiri, and returned via the Subansiri and Yume Chu valleys. The last such circumambulation took place in 1956, after which the Sino-Indian border conflict has put an end to the practice.

Lower Subansiri Dam The Lower Subansiri Dam or Lower Subansiri Hydro-Electric Project is an under-construction dam gravity dam on the river. The dam is seen as a problem with environmental and social impacts, and many organisations are protesting against it. The River is a fiction book based on the issue and displays the issue as viewed by common Assamese people through its imaginary dolphins, fishes, and human characters.

See also List of rivers of Assam Lower Subansiri Dam

Notes

References

Bibliography

External links Subansiri Basin Study – Another Chapter of Environment Subversion in Northeast, South Asia Network on Dams, Rivers and People, 25 September 2013.