The Ganga system: headwaters, main stem and delta

Detail

1. Why the Ganga matters

• The Ganga river is India's most important river. Two things make it so:
• Its basin. A basin (catchment) is all the land whose rain and snowmelt drain into one river.

• Its place in Indian culture and religion.

• The Ganga basin is the largest river basin in India. It covers about 27% of India's land and supports about 47% of its people (PIB, March 2025) [4]. (NCERT and other sources give about 26% and over 500 million people.)

• The whole basin covers about 10 lakh sq km. It spreads over 4 countries: China (Tibet), Nepal, India and Bangladesh [2]. The figure is 10,86,000 sq km if the Ganga sub-basin is counted in full [3].
• The part of the basin inside India is 8,61,404 sq km, which is 26.2% of India's area (CWC) [3]. (NCERT: about 8.6 lakh sq km.)
• Location: the basin lies between 22.45°N and 31.47°N latitude and 73.37°E and 89.31°E longitude [2].
• 11 states/UT: Uttar Pradesh, Uttarakhand, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, Rajasthan, West Bengal, Haryana, Himachal Pradesh and Delhi [2].

State (older boundaries, CWC)	Basin area in India (sq km)
Uttar Pradesh (incl. present Uttarakhand)	2,94,364
Madhya Pradesh (incl. present Chhattisgarh)	1,98,962
Bihar (incl. present Jharkhand)	1,43,961
Rajasthan	1,12,490
West Bengal	71,485
Haryana	34,341
Himachal Pradesh	4,317
Delhi	1,484
[3]

• Land use and water stress [4]:
• About 65.57% of the basin is farmland, and 3.47% is covered by water bodies.
• The basin receives 35.5% of India's total rainfall input.
• Even so, it is India's second most water-stressed basin, after the Sabarmati. Water stress means demand comes close to the water available.
• The reason is the huge population. Each person gets only 39% of the average yearly rainwater per person across India's major basins.

2. Headwaters: the Bhagirathi

• Gangotri glacier: a glacier is a large, slow-moving river of ice. The Gangotri glacier is in Uttarkashi district, Uttarakhand.
• Gaumukh ("cow's mouth") is the snout of the glacier, at 3,900 m. A snout is the lower edge of a glacier, where the ice melts. This meltwater is the source of the Bhagirathi river.
• The upper part of the Gangotri glaciers lies much higher, at about 7,000 m [2].

• So the river starts at 3,900 m (the snout), but its ice comes from about 7,000 m.

• Course: the Bhagirathi cuts through the Central and Lesser Himalayas in narrow gorges. A gorge is a deep, narrow valley with steep sides, cut by a fast river.

• The Tehri dam is on the Bhagirathi.
• The Gangotri glacier is retreating. Its snout is moving back up the valley year after year.
• Warmer temperatures → more ice melts than new snow can replace → the snout moves upstream.
• Over a long time this can change how much water the Ganga carries in the dry season.

3. Headwaters: the Alaknanda and the Panch Prayag

• The Alaknanda river rises in the Satopanth glacier, above Badrinath.
• A confluence is the place where two or more rivers meet. In the Garhwal hills a confluence is called a prayag (a sacred meeting point).
• At Devprayag the Bhagirathi and the Alaknanda meet. From here on the river is called the Ganga. (NCERT exercise 1(v).)
• The source streams of the Alaknanda:
• The Dhauli and the Vishnu Ganga meet at Joshimath (Vishnuprayag).
• The Pindar joins at Karnaprayag.
• The Mandakini (Kali Ganga) joins at Rudraprayag.

Panch Prayag: the five sacred confluences on the Alaknanda, from upstream to downstream

Order	Prayag	River joining the Alaknanda	Note
1	Vishnuprayag	Dhauliganga	near Joshimath
2	Nandprayag	Nandakini	—
3	Karnaprayag	Pindar	—
4	Rudraprayag	Mandakini	Mandakini comes down from the Kedarnath side
5	Devprayag	Bhagirathi	the Ganga begins here

• Other important confluences:
• Triveni Sangam, Prayagraj (UP): the Ganga, the Yamuna and the mythical (believed but not real) Sarasvati meet here. The Kumbh Mela is held here.
• Harike (Punjab): the Beas joins the Satluj. The Harike wetland is here.

4. Main stem: from the mountains to the plains

• The main stem is the main channel of a river, not counting its tributaries.
• The Ganga enters the plains at Haridwar. (CWC says the combined stream enters the plains at Rishikesh, just upstream of Haridwar [2].)
• Direction of flow: first south, then south-east, then east.
• Length: 2,525 km in total (CWC also gives this figure [3]).

State	Length of the Ganga (km)
Uttarakhand	110
Uttar Pradesh	1,450 (longest stretch)
Bihar	445
West Bengal	520

• Tributaries: a tributary is a smaller river that flows into a bigger one.
• Right bank (joins from the south, from the Peninsular plateau): the Son is the major one. It rises on the Amarkantak plateau. The Yamuna also joins from the right bank at Prayagraj.
• Left bank (joins from the north, from the Himalayas): the Ramganga, Gomati, Ghaghara, Gandak, Kosi and Mahananda.

• CWC's list of principal tributaries: Yamuna, Ramganga, Gomti, Ghaghra, Son, Gandak, Burhi Gandak, Kosi and Mahananda [2]. Chambal and Betwa are important sub-tributaries (they join the Yamuna, not the Ganga) [3].

• Why the left-bank rivers matter more for floods:

• They come from the high Himalayas. They are fed by snow and monsoon rain.
• They carry a lot of silt (fine soil). When it settles, the riverbed rises and the river often changes its course. The Kosi is the best-known example.
• The right-bank rivers drain the old, stable plateau. Most depend only on rain, so they carry less water in the dry season.

5. Rivers crossed along the foothills (NCERT exercise 4(ii))

• Going west to east from Haridwar to Siliguri, along the Himalayan foothills, you cross: Ganga → Ramganga → Sarda → Ghaghara → Rapti → Gandak → Bagmati → Kosi → Mahananda.

• This order is a common MCQ. The Sarda (Kali) forms the India–Nepal border and joins the Ghaghara.

6. The delta: Farakka, Hugli and Padma

• A delta is a fan-shaped area of new land at a river's mouth. It forms in steps:
• The river slows down as it reaches the sea.
• It drops its silt.

• The silt builds new land, and the river splits into many branches (distributaries).

• The split: at Farakka (West Bengal) the Ganga splits into two branches [2]:

• Bhagirathi–Hugli (flows through West Bengal). CWC calls this "the former main course" of the river [3].

• Padma river (flows into Bangladesh) [2].

• Hugli branch: it reaches the Bay of Bengal at Sagar Island. The Gangasagar Mela is held here at Makar Sankranti (mid-January).

• Padma branch:
• In Bangladesh it receives the Jamuna, which is the main stream of the Brahmaputra.
• Further down it joins the Meghna.

• It then reaches the Bay of Bengal under the name Meghna.

• Together the Ganga and the Brahmaputra build the Ganga–Brahmaputra delta, the largest delta in the world. The Sundarbans mangrove forest is on this delta.

7. Cleaning the Ganga

Earlier steps

• Ganga Action Plan (1985): the first big plan to clean the river.
• Ganga declared National River (2008).
• Gangetic dolphin declared National Aquatic Animal (2009). The dolphin needs clean, flowing water, so it acts as an indicator species (its health shows the river's health).

Namami Gange (from 2014)

• Namami Gange was approved in June 2014 as the government's flagship (most important) programme. It is an Integrated Conservation Mission [4].
• Money [4]:
• First outlay: ₹20,000 crore for five years, up to March 2021.
• Extended to March 2026 with ₹22,500 crore more.

• Outlay for the National Ganga Plan in 2025-26: ₹3,400 crore.

• Who runs it:

• NMCG (National Mission for Clean Ganga) carries out the work.

• The National Ganga Council sits at the top and guides it.

• Pillars: sewerage (treating dirty water from towns), river-front development, river-surface cleaning, biodiversity, afforestation (planting trees), public awareness, monitoring of industrial effluents (factory waste water) and Ganga Gram (cleaner villages on the river bank).

• Vision [4]:
• Aviral Dhara: continuous flow.
• Nirmal Dhara: unpolluted flow.

• Keeping the river's geological and ecological integrity, meaning its natural shape and life stay healthy.

• Basin plan: a consortium (group) of seven IITs prepared the Ganga River Basin Management Plan (GRBMP). It treats the whole basin as one unit, an approach called Integrated River Basin Management [4].

• Four areas of work [4]:
• Nirmal Ganga: cutting pollution.
• Aviral Ganga: improving ecology and flow.
• Jan Ganga: connecting people with the river.

• Gyan Ganga: research and policy.

• Progress (as of 31 January 2025) [4]:

• 492 projects worth ₹40,121.48 crore were taken up, and 307 were completed.
• 203 sewerage projects (₹32,613 crore) were taken up, with 6,255 MLD of treatment capacity. MLD means million litres per day. 127 STPs (sewage treatment plants) with 3,446 MLD are working.
• 33,024 hectares were planted with trees along the main stem, at about ₹398 crore.
• 143.8 lakh fingerlings (young fish) of Indian Major Carp have been released since 2017. This adds to fish stocks and gives food (prey) to river dolphins.
• CETPs (Common Effluent Treatment Plants: shared plants that clean factory waste water) were sanctioned at Jajmau (Kanpur, 20 MLD), Banther (4.5 MLD) and Mathura (6.25 MLD). Jajmau and Mathura are complete.

Prelims Hooks

• Gaumukh (3,900 m) is the snout of the Gangotri glacier in Uttarkashi, Uttarakhand. It is the source of the Bhagirathi, not the Alaknanda.
• The Alaknanda rises in the Satopanth glacier above Badrinath.
• Panch Prayag, upstream to downstream: Vishnuprayag (Dhauliganga) → Nandprayag (Nandakini) → Karnaprayag (Pindar) → Rudraprayag (Mandakini) → Devprayag (Bhagirathi).
• The name "Ganga" starts at Devprayag, not at Gangotri or Haridwar.
• Length by state: UP (1,450 km) > West Bengal (520 km) > Bihar (445 km) > Uttarakhand (110 km). Trap: West Bengal's stretch is longer than Bihar's.
• Foothill rivers, west to east (Haridwar to Siliguri): Ganga, Ramganga, Sarda, Ghaghara, Rapti, Gandak, Bagmati, Kosi, Mahananda.
• The Son is the major right-bank tributary. The Ramganga, Gomati, Ghaghara, Gandak, Kosi and Mahananda join from the left bank.
• The Ganga splits at Farakka (West Bengal) into the Bhagirathi–Hugli and the Padma [2]. The Padma joins the Jamuna (Brahmaputra) and reaches the sea as the Meghna.
• Sagar Island is at the Hugli mouth, where the Gangasagar Mela is held at Makar Sankranti. Harike is the Beas–Satluj confluence.
• The Ganga basin is India's largest basin (about 26–27% of India's area) but its second most water-stressed, after the Sabarmati [3][4].
• Dates: Ganga Action Plan 1985, National River 2008, Gangetic dolphin as National Aquatic Animal 2009, Namami Gange June 2014 (extended to March 2026 with ₹22,500 crore [4]).

Mains Points

• Retreating glaciers threaten the Ganga's dry-season flow (GS-I/III):
• Warmer temperatures shrink the Gangotri glacier.
• Less meltwater reaches the river in the lean season (the dry months before the monsoon).
• Water for irrigation, drinking and dams such as Tehri is at risk.

• Adaptation needs: glacier monitoring, environmental flows (a minimum amount of water always left in the river) and watershed management.

• A rich basin that is still water-stressed (GS-I):

• The basin gets 35.5% of India's rainfall but supports about 47% of its people. About 65.57% of its land is farmed [4].
• So each person gets little water, and groundwater is over-used.

• Rainfall is plentiful, but the basin ranks second only to the Sabarmati in water stress [4].

• The Himalayan left-bank tributaries make the plains fertile but flood-prone (GS-I/III):

• Rivers like the Kosi and Gandak carry heavy silt from young mountains.
• The silt raises their beds, so they spill and shift course, causing floods in north Bihar.

• The same silt renews the fertile alluvial soil (soil laid down by rivers) of the plains.

• Ganga cleaning has moved from projects to managing the whole basin (GS-III):

• Early plans: Ganga Action Plan (1985) and the National River status (2008).
• Namami Gange (2014) uses a basin plan made by seven IITs (GRBMP) and aims for Aviral (continuous) and Nirmal (unpolluted) Dhara.
• Progress: 3,446 MLD of sewage treatment capacity working, and 33,024 ha afforested by January 2025 [4].
• Problems that remain: the gap between sewage produced and sewage treated, factory pollution at places like Kanpur (Jajmau CETP), and barrages that cut river flow and harm dolphin habitat.