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The Ganga and Brahmaputra systems

Drainage of India · Part 2 / 4 · Fact-checked on 8 November 2026 · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

The headstreams of the Ganga and the five prayags; its course to the Padma and the Sundarbans delta; its left-bank and right-bank tributaries, including the Kosi, the Yamuna with the Chambal, the Son and the Damodar; the Brahmaputra from Tibet through Assam with its tributaries; and the canals, dams, floods, silt and pollution of the northern rivers.

Part 1 followed the Indus; this part moves east to the two river systems that carry most of north India's water, the Ganga and the Brahmaputra. Together with the Meghna they form one of the largest river systems on Earth, and their sediment built the Ganga and Brahmaputra plains and the delta at their joint mouth. The Ganga basin alone covers about a quarter of India and supports a very large share of its people, its farmland and its cities. This part traces the Ganga from its glacier sources and mountain confluence points to the sea, sorts its many tributaries into those arriving from the north and those arriving from the south, follows the Brahmaputra from Tibet through Assam, and ends with the uses and troubles of these rivers: canals, dams, floods, silt and pollution.

The Ganga has two main headstreams in the Garhwal Himalaya of Uttarakhand. The Bhagirathi emerges from an ice cave called Gaumukh at the snout of the Gangotri glacier, while the Alaknanda gathers its water from the Satopanth glacier above Badrinath. As the Alaknanda descends it is fed, one after another, by side rivers at five sacred meeting points known as the Panch Prayag: the Dhauliganga at Vishnuprayag, the Nandakini at Nandprayag, the Pindar at Karnaprayag, the Mandakini at Rudraprayag and, last and most important, the Bhagirathi itself at Devprayag. Only below Devprayag does the united stream take the name Ganga. It then cuts through the Shiwalik hills and leaves the mountains at Haridwar, where it enters the plains. Because the Bhagirathi is fed by a glacier, the river keeps flowing even in the driest months.

From Haridwar the Ganga flows south and then south-east across the plains of Uttar Pradesh, past Kanpur, and is joined by the Yamuna at Prayagraj (formerly Allahabad) before reaching Varanasi. In Bihar it passes Patna and gathers the big rivers from Nepal and the Son from the south, then bends round the Rajmahal hills into West Bengal. Near Farakka a barrage, completed in 1975, diverts part of its flow into a feeder canal that tops up the Bhagirathi-Hooghly, the branch that runs south past Kolkata; the aim was to flush silt from the Hooghly and keep the Kolkata port usable. The main channel turns south-east into Bangladesh, where it is called the Padma. Sharing the dry-season water at Farakka became a long-running issue with Bangladesh, settled for the time being by a treaty in 1996, which Part 4 takes up.

In Bangladesh the Padma receives the Brahmaputra, known there as the Jamuna, and further down the Meghna, and the combined waters spread through countless channels into the Bay of Bengal. Their deposits have built the Ganga-Brahmaputra delta, the largest delta in the world, shared between West Bengal and Bangladesh. Its seaward edge is the Sundarbans, a maze of tidal creeks and mangrove forest named after the sundari tree and home to the Royal Bengal tiger. In India the river carries national symbols too. The Union government declared the Ganga the National River in 2008, and the Ganga-Bhagirathi-Hooghly stretch from Prayagraj to Haldia is National Waterway 1 under the National Waterways Act, 2016. The Ganges river dolphin, which lives in these waters, was declared India's national aquatic animal in 2009.

The tributaries that join the Ganga from the north, on its left bank, are Himalayan rivers. The Ramganga rises in the Garhwal hills and joins near Kannauj. The Gomti is an exception: it begins in the plains of Pilibhit district, is fed by rain and groundwater rather than snow, and flows past Lucknow. The Ghaghara rises in Tibet, crosses Nepal, where it is called the Karnali, and meets the Ganga near Chhapra in Bihar. The Gandak, formed in Nepal from streams such as the Kali Gandaki, enters Bihar in Champaran and joins the Ganga at Sonpur, opposite Patna. The Kosi drains the region around Mount Everest through seven headstreams, which is why Nepal calls it the Sapta Kosi, and the Mahananda, coming down from the Darjeeling hills, is the last left-bank tributary, joining in West Bengal.

These northern rivers bring life and also danger. They come down steep mountain slopes loaded with sand and gravel, and when they reach the nearly flat plain they suddenly lose speed and drop much of that load in their own beds. The beds rise, the banks overflow during the monsoon, and the river may abandon its channel for a lower one. The Kosi is the extreme case: over the last two centuries it has swung its course far to the west across north Bihar, burying fields under sand, which earned it the name 'sorrow of Bihar'. Embankments and a barrage near the India-Nepal border were built to hold it, but in August 2008 the river breached its eastern embankment at Kusaha in Nepal and poured into a channel it had left long before, flooding large parts of Bihar.

On the right bank the biggest tributary is the Yamuna. It rises at the Yamunotri glacier on the slopes of the Bandarpunch range, receives the Tons in the hills, and then runs roughly parallel to the Ganga past Delhi and Agra before meeting it at the Triveni Sangam in Prayagraj. Most of its own right-bank tributaries come from the plateau to the south: the Chambal, Sind, Betwa and Ken. The Chambal rises near Mhow in the Malwa plateau and flows north through Kota, where a chain of dams, Gandhi Sagar, Rana Pratap Sagar and Jawahar Sagar, with the Kota barrage below, uses its water. Lower down it has carved soft alluvium into a maze of gullies and ravines, the Chambal badlands. The National Chambal Sanctuary, shared by Madhya Pradesh, Rajasthan and Uttar Pradesh, protects the gharial in this stretch.

Two more right-bank rivers come straight off the plateau. The Son rises on the Amarkantak plateau, the same high ground that gives rise to the Narmada, and flows north and then north-east to join the Ganga upstream of Patna; the Rihand dam stands on its tributary, the Rihand. The Damodar rises in the Chota Nagpur plateau of Jharkhand and flows east through a rift valley that holds some of India's richest coal deposits, joining the Hooghly below Kolkata. Its sudden monsoon floods earned it the name 'sorrow of Bengal'. To tame it, the Damodar Valley Corporation was set up by an Act of Parliament in 1948, modelled on the Tennessee Valley Authority of the United States. It became independent India's first multipurpose project, combining flood control, irrigation, hydropower and thermal power, with dams such as Tilaiya, Konar, Maithon and Panchet.

The Brahmaputra begins far from India, at the Chemayungdung glacier in the Kailash range of south-west Tibet, not far from the sources of the Indus and the Satluj. As the Yarlung Tsangpo it flows east for a very long distance across the dry plateau of southern Tibet. Near the peak of Namcha Barwa it makes a sharp hairpin turn, the Great Bend, and plunges through one of the deepest gorges on Earth before entering Arunachal Pradesh, where it is called the Siang or Dihang. In the Assam plains it is joined by the Dibang and the Lohit and from there is called the Brahmaputra. The river's steep fall at the Great Bend makes it attractive for hydropower, and in July 2025 China began building a very large hydropower project on the lower Yarlung Tsangpo, which raises concern in India and Bangladesh about downstream flows.

Across the Assam valley the Brahmaputra is wide, shallow and braided: it splits into many channels around shifting sandbars and then rejoins. In one wide stretch the channels enclose Majuli, a very large inhabited river island and a centre of Assam's Vaishnava monasteries, made a district in 2016. Tributaries arrive from both sides. From the Himalaya on the north, or right bank, come the Subansiri, its largest tributary, the Kameng, the Manas from Bhutan and, further west, the Tista from Sikkim, which joins in Bangladesh. From the south, or left bank, come the Burhi Dihing, the Dhansiri and the Kopili. Near Dhubri the river turns south into Bangladesh as the Jamuna. Heavy rain, steep slopes, a huge silt load and an earthquake-prone setting make floods in Assam an almost yearly event, and riverbank erosion keeps eating into villages and farmland.

The northern rivers have long been harnessed. The Upper Ganga Canal, taking off at Haridwar and opened in 1854, was one of the earliest large canal systems of British India, and canals from the Ganga, Yamuna and Sharda still water the Doab of western Uttar Pradesh. In the hills, the Tehri dam on the Bhagirathi, among the tallest dams in India, supplies power and drinking water. The same rivers also carry heavy loads of pollution from cities, industries and farms. The Ganga Action Plan was launched in 1986. Its present successor, the Namami Gange programme, approved in 2014 and run by the National Mission for Clean Ganga under the Ministry of Jal Shakti, builds sewage treatment plants, cleans river fronts and ghats, plants trees along the banks and works on keeping enough water flowing in the river through the year.

Taken together, the Ganga and Brahmaputra systems explain much of north and north-east India. Snow-fed headstreams keep the main rivers flowing all year, so each is a perennial river that can feed canals even in the dry season. Tributaries from the north bring water and silt, and with them floods and shifting channels; tributaries from the south bring plateau water, ravines and dam sites. The same silt that fertilises the plains clogs channels, raises beds and builds the delta at the sea. Part 3 turns south to the older, rain-fed rivers of the Peninsula.

Exam traps

• The Alaknanda, not the Bhagirathi, passes through four of the five prayags; the Bhagirathi joins it only at the last one, Devprayag, and only below Devprayag is the river called the Ganga.
• Order of the prayags going downstream: Vishnuprayag, Nandprayag, Karnaprayag, Rudraprayag, Devprayag. Mandakini is the river at Rudraprayag; Pindar at Karnaprayag.
• The Gomti is a left-bank tributary but is NOT snow-fed: it rises in the plains of Pilibhit district.
• The Son and the Damodar are right-bank rivers from the plateau. Kosi = 'sorrow of Bihar'; Damodar = 'sorrow of Bengal'. Do not swap them.
• The Chambal joins the Yamuna, not the Ganga directly; the Betwa and Ken are also Yamuna tributaries.
• In Bangladesh the Brahmaputra is the Jamuna and the Ganga is the Padma; do not confuse the Jamuna of Bangladesh with India's Yamuna.
• The Subansiri, Kameng, Manas and Tista are right-bank (northern) tributaries of the Brahmaputra; the Burhi Dihing, Dhansiri and Kopili are left-bank.
• The Farakka barrage (1975) diverts water into the Bhagirathi-Hooghly to keep Kolkata port working; it is not mainly a hydropower dam.

Recap

• Headstreams: Bhagirathi from Gaumukh (Gangotri glacier), Alaknanda from the Satopanth glacier; they unite at Devprayag to form the Ganga.
• Panch Prayag: Vishnuprayag (Dhauliganga), Nandprayag (Nandakini), Karnaprayag (Pindar), Rudraprayag (Mandakini), Devprayag (Bhagirathi).
• Course: Haridwar, Kanpur, Prayagraj (Yamuna joins), Varanasi, Patna, Farakka barrage (1975), Padma in Bangladesh.
• Delta: Ganga-Brahmaputra delta, the world's largest; the Sundarbans mangroves. National River 2008; NW-1 Prayagraj to Haldia; river dolphin national aquatic animal 2009.
• Left bank: Ramganga, Gomti (plains-fed), Ghaghara, Gandak, Kosi ('sorrow of Bihar'), Mahananda.
• Right bank: Yamuna (with Chambal, Sind, Betwa, Ken), Son, Damodar ('sorrow of Bengal'; DVC 1948).
• Brahmaputra: Chemayungdung glacier; Yarlung Tsangpo, Great Bend at Namcha Barwa, Siang/Dihang, joined by Dibang and Lohit; Majuli; Jamuna in Bangladesh.
• Brahmaputra tributaries: right bank Subansiri, Kameng, Manas, Tista; left bank Burhi Dihing, Dhansiri, Kopili.
• Uses and problems: Upper Ganga Canal (1854), Tehri dam, floods, silt, pollution; Ganga Action Plan (1986) and Namami Gange (2014).

Practice questions

Sources

• Central Water Commission, Ministry of Jal Shakti, and India-WRIS: Ganga and Brahmaputra basin reports, tributaries and basin areas — https://cwc.gov.in
• Survey of India, Department of Science and Technology: physical map of India showing the courses of the Ganga, the Brahmaputra and their tributaries — https://surveyofindia.gov.in
• National Mission for Clean Ganga, Ministry of Jal Shakti: Namami Gange programme, the Ganga as National River (2008), the Ganges river dolphin, and the Ganga Action Plan — https://nmcg.nic.in
• Damodar Valley Corporation (set up under the Damodar Valley Corporation Act, 1948): history, dams and functions — https://www.dvc.gov.in
• The National Waterways Act, 2016 (National Waterway 1: Ganga-Bhagirathi-Hooghly river system, Prayagraj to Haldia), and Inland Waterways Authority of India — https://iwai.nic.in
• Brahmaputra Board and Ganga Flood Control Commission, Ministry of Jal Shakti: floods, erosion and the Kosi and Brahmaputra basins; Majuli — https://brahmaputraboard.gov.in
• Ministry of External Affairs and Press Information Bureau: India's statements on Chinese hydropower construction on the Yarlung Tsangpo (2025) — https://www.mea.gov.in
• THDC India Limited, Ministry of Power: Tehri dam on the Bhagirathi — https://www.thdc.co.in
• Farakka Barrage Project, Ministry of Jal Shakti: barrage and feeder canal to the Bhagirathi-Hooghly — https://fbp.gov.in
• Ministry of Environment, Forest and Climate Change and state forest departments: National Chambal Sanctuary (Madhya Pradesh, Rajasthan, Uttar Pradesh) and the gharial — https://moef.gov.in