Brahmaputra river system: notes for bank exams

At a glance

The Brahmaputra rises in Tibet as the Yarlung Tsangpo, enters India in Arunachal Pradesh as the Siang, becomes the Brahmaputra in Assam and flows into Bangladesh as the Jamuna before joining the Ganga and Meghna. It carries huge volumes of water and silt, floods Assam almost every year, and is now at the centre of rival mega-dam plans by China and India.

Key facts

Source: Chemayungdung glacier, near Lake Mansarovar in south-western Tibet (some studies place it at the Angsi glacier)
Length: about 2,900 km (estimates vary with the method used)
Names: Yarlung Tsangpo (Tibet) → Siang or Dihang (Arunachal Pradesh) → Brahmaputra (Assam) → Jamuna (Bangladesh)
Great bend: around Namcha Barwa peak in Tibet, before it enters India
Becomes the Brahmaputra: near Sadiya in Assam, where the Dibang and Lohit join the Siang
Joins: the Padma (Ganga) in Bangladesh, then the Meghna, before the Bay of Bengal
Majuli: largest river island in India and India's first island district (2016)
Umananda (Guwahati): among the smallest inhabited river islands
National Waterway 2: Sadiya to Dhubri, about 891 km
Medog (Motuo) hydropower project, China: construction began 19 July 2025; about 60 GW planned
Siang Upper Multipurpose Project, India: about 11,000 MW and about 9.2 billion cubic metres of storage, proposed by NHPC

How it works

Main tributaries in India.

Bank	Tributaries
Right (north)	Subansiri, Kameng (Jia Bharali), Manas, Sankosh
Left (south)	Dibang, Lohit, Burhi Dihing, Dhansiri, Kopili

The Teesta joins the Brahmaputra (Jamuna) inside Bangladesh.

Why it floods. Heavy monsoon rain on steep Himalayan slopes, a heavy silt load that raises the river bed, earthquakes and landslides, and a narrow Assam valley combine to cause frequent floods and erosion. The river is braided, with many channels and sandbars.

Bridges to know. Dhola–Sadiya (Bhupen Hazarika Setu, on the Lohit, 2017) and Bogibeel (India's longest rail-cum-road bridge, near Dibrugarh, 2018).

The dam question. China's Medog project sits just before the river enters India. India fears sudden releases or reduced lean-season flows. The Centre sees the Siang Upper project as a strategic storage that could buffer such shocks and control floods. Local Adi communities oppose it because it would submerge villages and farmland.

Recent developments

23–24 Oct 2026: Protests against the Siang Upper Multipurpose Project turned violent at Pasighat, East Siang district, after a 12-hour bandh; an NHPC office and a police station were set on fire. Chief Minister Pema Khandu appealed for calm and said public consensus would stay central to the project.

Exam traps

In Arunachal the river is the Siang/Dihang; it is called the Brahmaputra only after the Dibang and Lohit join near Sadiya.
In Bangladesh it is the Jamuna, not the Padma; the Padma is the Ganga.
Majuli is on the Brahmaputra in Assam, not in Arunachal.
The Teesta joins the Brahmaputra in Bangladesh, not in India.
Medog is China's dam (Tibet); Siang Upper is India's proposed project (Arunachal).

Quick check

Q: What is the Brahmaputra called in Tibet? A: Yarlung Tsangpo.
Q: Which river island in the Brahmaputra became India's first island district? A: Majuli.
Q: Which company is proposing the Siang Upper Multipurpose Project? A: NHPC.

Brahmaputra river system