Drainage System of the Himalayan Rivers: Indus, Ganga, Brahmaputra River Networks

At a Glance

• Nature Perennial, snow-fed and rain-fed
• Indus Flows to the Arabian Sea
• Ganga Flows to the Bay of Bengal
• Brahmaputra Rises in Tibet, braided
• Treaty Indus Waters Treaty, 1960
• Exam link UPSC Prelims, Geography: Physical Geography of India

Where Does It Fit?

This topic follows the geological regions and takes the first of the two great drainage systems of India, the Himalayan rivers. They drain the Himalaya and the northern plains, while the next topic describes the rivers of the Peninsula. Previous topic: Geological Regions of India: Deccan Plateau, The Himalayas, Other Peninsular Mountain Ranges, Indo-Gangetic-Brahmaputra Plain. Next topic: Drainage System of the Peninsular Rivers: East-Flowing and West-Flowing Rivers.

What Is the Course of the Indus?

In short: the Indus is an antecedent river that starts in Tibet, runs along the Himalayas and crosses Ladakh before turning south through a deep gorge to the plains of Pakistan.

The Indus, known as the Sindhu in Sanskrit and the origin of the name India, rises from glaciers in the Kailas range near Lake Manasarovar. It flows north-west through Tibet, enters Ladakh and flows between the Ladakh and Zanskar ranges, at an average height of about 4,000 m with a very gentle gradient. The Zanskar joins it near Leh, and the Shyok joins near Skardu, with the Gilgit, Hunza and Dras among other Himalayan tributaries. North of Nanga Parbat, it makes a sharp southward turn, the western syntaxial bend, and cuts a gorge more than 5,000 m deep, as in Geological Regions of India: Deccan Plateau, The Himalayas, Other Peninsular Mountain Ranges, Indo-Gangetic-Brahmaputra Plain. The Kabul river joins it near Attock; it crosses the Salt Range, and above Mithankot it receives the Panjnad, which carries the combined water of the five Punjab rivers. It enters the Arabian Sea south of Karachi through a large delta. The total drainage area is about 1.1 million sq km, more than half of it in Pakistan.

What Are the Tributaries of the Indus?

In order from west to east the tributaries are the Jhelum, Chenab, Ravi, Beas and Sutlej, and in decreasing length, the Sutlej, Chenab, Ravi, Jhelum and Beas. The Beas–Sutlej–Ravi waters feed the Punjab and Haryana canal systems, and the Indira Gandhi Canal in Rajasthan, starting at Harike, brings water to the Thar desert.

What Is the Indus Waters Treaty and Where Does It Stand Now?

• The treaty: signed in 1960 with the World Bank as a party, it gives the three eastern rivers, the Ravi, Beas and Sutlej, to India for unrestricted use, and the three western rivers, the Indus, Jhelum and Chenab, mainly to Pakistan, with India allowed run-of-the-river hydropower and limited irrigation on them. In practice, India uses about 20 per cent of the system’s water. Disputes are handled through the Permanent Indus Commission, a neutral expert, and a court of arbitration.
• Projects: India’s hydropower projects on the western rivers include Baglihar and Salal on the Chenab, Kishenganga on a tributary of the Jhelum and Ratle on the Chenab, and Pakistan has raised objections on design features of some.
• Abeyance: in April 2025, after the Pahalgam attack, India announced that it was holding the treaty in abeyance. Pakistan rejected the move and called the treaty binding.
• Arbitration: on 31 August 2026, the Court of Arbitration at the Permanent Court of Arbitration held that the abeyance neither suspended nor terminated the treaty, and issued an interim order limiting work on the Ratle dam. India rejected the ruling, calling the court illegally constituted, and says that the abeyance remains in force. The separate neutral expert process on Kishenganga and Ratle continues, with a decision expected around mid-2027.

As an analytical point, the Indus treaty was seen for decades as a model of cooperation between rivals, and the present dispute shows how far water law now depends on political relations. Physically, India has limited storage on the western rivers, so changes in the use of water would take years of construction, whereas the legal and diplomatic effects are immediate. The Ganga and Brahmaputra systems face similar questions.

What Is the Course of the Ganga?

In short: the Ganga collects the water of many Himalayan and peninsular rivers and carries it across the plain to the Bay of Bengal.

The Ganga starts as the Bhagirathi from the Gangotri glacier in Uttarakhand, at the Gaumukh, as in Geological Regions of India: Deccan Plateau, The Himalayas, Other Peninsular Mountain Ranges, Indo-Gangetic-Brahmaputra Plain. At Devprayag the Bhagirathi meets the Alaknanda, and from there the river is called the Ganga. The Alaknanda is joined on its way by the Dhauliganga at Vishnuprayag, the Nandakini at Nandprayag, the Pindar at Karnaprayag and the Mandakini at Rudraprayag, together the Panch Prayag. The Ganga leaves the mountains at Haridwar, meets the Yamuna at Prayagraj, and flows eastward, joined by the Son near Patna and the Kosi near Kursela. Near the Rajmahal hills it turns south-east, and at Farakka it splits: the Bhagirathi-Hooghly flows south through West Bengal, and the main stream flows into Bangladesh as the Padma, where it meets the Brahmaputra, called the Jamuna there, at Goalundo and later the Meghna. The river then pours into the Bay of Bengal through the largest delta in the world, the Ganga-Brahmaputra delta, as in Indo-Gangetic-Brahmaputra Plain. The length is about 2,525 km, measured along the Hooghly.

What Are the Tributaries of the Ganga?

The Kosi is the most notorious: after it leaves the hills it becomes sluggish and deposits sand, its braided channel shifts widely, and it has changed its course by over 100 km in two centuries. The embankments and the barrage at Hanuman Nagar near the Nepal border, built in 1965, failed to stop the breach of 2008, which displaced millions in Bihar. The Chambal, Betwa, Ken and Son come from the Peninsular Plateau, as in Drainage System of the Peninsular Rivers: East-Flowing and West-Flowing Rivers.

What Are the Issues in the Ganga Basin?

• Pollution and rejuvenation: the Ganga was declared a national river in 2008, and the Ganga Action Plan began in 1986. Under the Namami Gange mission, launched in 2014, the National Mission for Clean Ganga builds sewage treatment plants, cleans the ghats and riverfronts, and promotes afforestation and biodiversity. The mission reported that more than 4,000 million litres a day of sewage treatment capacity had been created by mid-2026, but capacity built does not always mean capacity in use, since much of the pollution still comes from untreated drains and industrial effluents.
• Biodiversity: the Gangetic river dolphin, the national aquatic animal since 2009, numbered about 6,300 in the 2021–2023 survey across the Ganga and Brahmaputra basins.
• Water sharing: the Farakka Barrage, which started operating in 1975, diverts water to the Hooghly to flush silt from Kolkata port. The 1996 Ganges Water Treaty with Bangladesh shares the lean-season flow at Farakka, and it is due to expire on 12 December 2026, so renewal is under discussion in the bilateral mechanism, with Bangladesh seeking a long-term arrangement and a guarantee clause.
• Floods and groundwater: floods in Bihar, eastern Uttar Pradesh and West Bengal, and arsenic in the groundwater of the middle and lower plain.
• Navigation: National Waterway 1 runs along the Ganga from Haldia to Prayagraj.

As an analytical point, the Ganga basin supports around 40 per cent of India’s people on about a quarter of its land, so the river is as much a development and governance question as a religious and ecological one: cleaning it requires control of the pollution of cities, the minimum flow of the river, the management of the floodplain, and coordination between a number of states and neighbours.

What Is the Course of the Brahmaputra?

The northern or left-bank tributaries in the Assam valley include the Subansiri, Kameng, Manas, Dhansiri and Sankosh; the Tista, which once flowed into the Ganga but shifted east to the Brahmaputra after the floods of 1787, joins in Bangladesh. The Dibang and Lohit join from the north-east. The southern tributaries, such as the Burhi Dihing and Kopili, are shorter.

Why Is the Brahmaputra a River of Sorrow and Strength?

• Floods and erosion: the Brahmaputra carries an enormous amount of water and silt. The monsoon rainfall in the Himalayan foothills is among the heaviest in India, the channel is braided, and the banks are weak, so floods in Assam are annual and the river erodes its banks and islands. Majuli, once much larger, has lost a large part of its area to erosion. Majuli is known as the largest river island in the world and became a district in 2016.
• Transport and bridges: National Waterway 2 runs from Dhubri to Sadiya. The Bogibeel Bridge near Dibrugarh, opened in 2018, is a rail-and-road bridge, and the Dhola–Sadiya bridge opened in 2017.
• Hydropower: the Brahmaputra basin holds a large share of India’s hydropower potential, mostly in Arunachal Pradesh, but projects face seismic, flood and displacement concerns, as in epicentre above it Main cause Sudden slip along faults at plate boundaries Scales Magnitude…">Earthquakes: Types, Causes, Effects and Frequency.
• Fertility and biodiversity: Kaziranga and Manas lie on the plain of the river, and the Ganges river dolphin lives in it.

What Is the Medog Dam Debate?

China started building a huge hydropower project on the lower Yarlung Tsangpo, near the Great Bend at Medog in Tibet, with a groundbreaking in July 2025. The planned capacity is about 60 gigawatts, and the estimated cost is about 1.2 trillion yuan, which would make it much larger than the Three Gorges Dam. Downstream states and Bangladesh are concerned about the effects on flow, sediment and flood warnings, and about the risk of building in a region of high seismic activity at the meeting of the plates. India has asked for transparency and data-sharing. India has proposed the Siang Upper Multipurpose Project in Arunachal Pradesh, of about 11,000 MW, which would store water and act as a buffer, but local Adi communities oppose it because it would submerge many villages, and its approval and construction status should be checked against current reports. China is not a party to a water-sharing treaty with India, and cooperation is limited to hydrological data sharing arrangements.

As an analytical point, the Brahmaputra shows the difficulties of an upstream-downstream relationship without a treaty. The river carries a very large volume of water, but it is hard to measure and little used, so India needs flood forecasting, embankment and erosion management in Assam, and a diplomatic framework with China and Bangladesh.

Why Is This Topic Important?

• Facts Tributaries and confluences asked
• Current affairs Treaty status
• Strategy Water diplomacy

What Came Next?

The next topic describes the Peninsular rivers, east-flowing and west-flowing. Next topic: Drainage System of the Peninsular Rivers: East-Flowing and West-Flowing Rivers.

Key People and Terms

• Sindhu Sanskrit name of the Indus
• Panjnad Combined waters of the five Punjab rivers
• Run-of-the-river Hydropower without large storage
• Permanent Indus Commission Treaty body of both countries
• Neutral expert Technical referee under the treaty
• Harike Confluence of Beas and Sutlej

Exam Corner

Mains Angle

Questions link the river system with the treaty. These points add depth.

• Geography Antecedent course
• Use Punjab canals and hydropower
• Law Treaty dispute