Maarg Manthan · Topic 15.3

Ganga River System

Geography › Drainage Systems of India · Topic 15.3

The Ganga rises as the Bhagirathi from the Gangotri glacier, is joined by the Alaknanda at Devprayag, enters the plains at Haridwar and flows about 2,525 km to the Bay of Bengal, forming the world's largest delta with the Brahmaputra. Its left-bank tributaries come from the Himalayas and the right-bank tributaries from the Peninsula. It is India's largest basin, home to a large part of the population, and is the focus of the Namami Gange mission.

6 min read · UPSC Prelims · Geography · Drainage Systems of India

At a Glance

Length About 2,525 km
Source Gangotri glacier (Bhagirathi)
Becomes Ganga At Devprayag
Enters the plain Haridwar
Divides at Farakka
Exam link UPSC Prelims, Geography: Drainage Systems of India

Where Does It Fit?

This is the third topic of the macro on the drainage systems of India. The previous topic described the Indus system, and this one covers the Ganga, the largest basin in India. The next topic describes the Brahmaputra river system. Previous topic: Indus River System. Next topic: Brahmaputra River System.

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 Himalayan Valleys, Snowline and Glaciers. 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?

Bank	Rivers	Features
Right bank (mostly peninsular)	Yamuna, Chambal, Betwa, Ken, Son, Damodar	Yamuna rises at Yamunotri on Bandarpunch, is the largest tributary, and joins at Prayagraj after about 1,376 km; the Chambal flows through the Malwa plateau and carves ravines; the Son rises at Amarkantak and joins near Patna; the Damodar, once the Sorrow of Bengal, flows in a rift valley with coal and industries and is called the Ruhr of India
Left bank (Himalayan)	Ramganga, Gomati, Ghaghra, Gandak, Burhi Gandak, Bagmati, Kosi	They bring heavy loads of silt and cause frequent floods and shift their courses; the Ghaghra, known as the Karnali in Nepal, rises in Tibet near Gurla Mandhata and has the Sarda and Rapti as tributaries; the Gandak joins at Hajipur; the Kosi, called Sorrow of Bihar, is formed by the Tumar, Arun and Sun Kosi and joins the Ganga near Kursela

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 Peninsular Drainage and East-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.

Why Is This Topic Important?

Facts Prayags and tributaries asked
Current affairs Namami Gange and the 1996 treaty
Hazard Kosi floods

What Came Next?

The next topic describes the Brahmaputra river system. Next topic: Brahmaputra River System.

Key People and Terms

Prayag Confluence of rivers
Gaumukh Snout of the Gangotri glacier
Farakka Barrage Barrage diverting water to the Hooghly
Namami Gange Mission for Ganga rejuvenation
Sorrow of Bihar The Kosi
Ruhr of India Damodar valley

Exam Corner

Points to Remember

Devprayag is where the Ganga is formed.
The Yamuna is the largest tributary.
The Kosi is the Sorrow of Bihar.
The river divides at Farakka.
National Waterway 1 is on the Ganga.

Do Not Confuse With

Right and left bank tributaries Peninsular versus Himalayan
Bhagirathi and Hooghly Upper source stream versus the delta distributary
Padma and Jamuna Ganga in Bangladesh versus Brahmaputra there

Memory Hook

Gangotri to Devprayag, Haridwar to the plain, Yamuna at Prayagraj, split at Farakka, then the delta.

Mains Angle

Questions ask for tributaries and rejuvenation. These points add depth.

Course Bank-wise tributaries
Problem Pollution and floods
Policy Namami Gange and treaty

A Question You May Face

An original practice question, not a past paper question.

“Describe the Ganga river system and evaluate the Namami Gange programme in cleaning the river.”

How to Answer

Course Source to delta.
Tributaries Left and right bank.
Issues Pollution, floods, sharing.
Evaluation Capacity versus outcomes.

GS Relevance

Prelims: source, confluences (prayags), tributaries by bank, Farakka, pollution programmes. GS Paper 1: drainage; GS Paper 3: water pollution, flood management and river rejuvenation.

Frequently Asked Questions

Where does the Ganga originate?

The Ganga originates as the Bhagirathi from the Gangotri glacier at Gaumukh in Uttarakhand. At Devprayag, the Bhagirathi meets the Alaknanda and from there the river is called the Ganga. It leaves the mountains at Haridwar and flows about 2,525 kilometres to the Bay of Bengal.

What are the Panch Prayag?

The Panch Prayag are the five confluences along the Alaknanda river in Uttarakhand: Vishnuprayag, Nandprayag, Karnaprayag, Rudraprayag and Devprayag. Devprayag, where the Alaknanda meets the Bhagirathi, is where the main Ganga is formed and takes its name, so the five are also important pilgrimage sites.

Why is the Kosi called the Sorrow of Bihar?

The Kosi brings a huge load of silt from the Himalaya and deposits it on the plain, which raises the bed, so the river has a braided channel and often shifts its course. Its frequent floods devastate large areas of Bihar, as in the breach of the embankment in 2008.

What is Namami Gange?

Namami Gange is a flagship mission launched in 2014 to clean and rejuvenate the Ganga. It builds sewage treatment plants, treats industrial effluents, develops riverfronts and ghats, supports afforestation and biodiversity protection, and is run by the National Mission for Clean Ganga.

What is the Farakka Barrage?

The Farakka Barrage in West Bengal, which started operating in 1975, diverts a portion of the Ganga water into the Bhagirathi-Hooghly to improve navigation to Kolkata port by flushing silt. The sharing of the Ganga water at Farakka with Bangladesh is governed by the treaty of 1996.

PYQ Practice — Statement Analysis

1 The Ganga is formed at Devprayag by the meeting of the Bhagirathi and the Alaknanda.

True

That is where the name Ganga starts.

2 The Chambal is a left-bank tributary of the Ganga.

False

It is a right-bank tributary of the Yamuna.

3 The Damodar river was called the Sorrow of Bengal.