Ganga river

Also called: Ganges, Ganga, Bhagirathi and Alaknanda, Devprayag confluence · Topic: Drainage System of India: Rivers, Basins and Patterns · NCERT: Class 6, Ch 3 "Landforms and Life"; Class 7, Ch 1 "Geographical Diversity of India"; Class 7, Ch 1 "The Story of Indian Farming"; Class 11, Ch 3 "Drainage System"; Class 11, Ch 6 "Landforms and their Evolution"

Meaning

The Ganga river is India's most important river. It is formed at Devprayag, where the Bhagirathi and the Alaknanda meet. It flows 2,525 km across the northern plains [3]. At Farakka (West Bengal) it splits into the Bhagirathi–Hugli and the Padma [2]. Both branches then reach the Bay of Bengal.

It matters for two reasons. Its basin is the largest in India and supports about 47% of India's people [4]. It also has a central place in Indian culture and religion. It was declared India's National River in 2008.

Explanation

Headwaters: two source rivers in the Garhwal Himalayas

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

• Alaknanda: the other source stream

• It rises in the Satopanth glacier, above Badrinath.

• The Dhauli and the Vishnu Ganga meet at Joshimath (Vishnuprayag).

• Prayag

• A confluence is a place where two or more rivers meet. In the Garhwal hills a confluence is called a prayag.
• Five sacred prayags lie on the Alaknanda. They are known as the Panch Prayag.

Order (upstream → downstream)	Prayag	River joining the Alaknanda
1	Vishnuprayag	Dhauliganga (near Joshimath)
2	Nandprayag	Nandakini
3	Karnaprayag	Pindar
4	Rudraprayag	Mandakini (from the Kedarnath side)
5	Devprayag	Bhagirathi. The river is called the Ganga from here on.

Main stem: from the mountains to the plains

• The main stem is a river's main channel. It does not include the tributaries.
• The Ganga enters the plains at Haridwar. CWC says the combined stream reaches the plains at Rishikesh, just upstream of Haridwar [2].
• Direction of flow: first south, then south-east, then east.
• Length by state:

State	Length (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 Yamuna joins at Prayagraj. The Son rises on the Amarkantak plateau and is the major right-bank tributary.
• Left bank (joins from the north, from the Himalayas): the Ramganga, Gomati, Ghaghara, Gandak, Kosi and Mahananda.
• CWC lists these principal tributaries: Yamuna, Ramganga, Gomti, Ghaghra, Son, Gandak, Burhi Gandak, Kosi and Mahananda [2].

• The Chambal and the Betwa are sub-tributaries. They join the Yamuna, not the Ganga [3].

• Why the left-bank rivers cause more floods

• They come from the high Himalayas and are fed by both snow and monsoon rain.
• They carry heavy silt (fine soil). The silt settles and raises the riverbed, so the river spills over and 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.

The delta: how the Ganga reaches the sea

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

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

• The split at Farakka (West Bengal) [2]:

• Bhagirathi–Hugli flows through West Bengal. CWC calls it "the former main course" of the river [3]. It reaches the Bay of Bengal at Sagar Island.

• Padma flows into Bangladesh [2]. There it receives the Jamuna, the main stream of the Brahmaputra. Further down it joins the Meghna and reaches the sea 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 grows on this delta.

The basin and its water stress

• A basin (catchment) is all the land whose rain and snowmelt drain into one river.
• The Ganga basin is India's largest river basin. It covers about 27% of India's land (PIB) [4]. NCERT gives about 26%.
• The whole basin covers about 10 lakh sq km and spreads over 4 countries: China (Tibet), Nepal, India and Bangladesh [2].
• The part inside India is 8,61,404 sq km, or 26.2% of India's area [3]. It covers 11 states/UT [2].
• Why there is water stress despite heavy rain
• Water stress means that demand for water comes close to the water available.
• The basin receives 35.5% of India's total rainfall input, and 65.57% of its land is farmed [4].
• Because the population is so large, each person gets only 39% of the average yearly rainwater per person across India's major basins [4].
• So it is India's second most water-stressed basin, after the Sabarmati [4].

Where it occurs

• Source region: Uttarkashi district, Uttarakhand (Gangotri glacier, Gaumukh). Alaknanda: Satopanth glacier above Badrinath. The two meet at Devprayag in the Garhwal hills.
• Main stem states: Uttarakhand → Uttar Pradesh → Bihar → West Bengal.
• Key places on the river:
• Rishikesh/Haridwar: the river enters the plains [2].
• Prayagraj (UP): the Yamuna joins at the Triveni Sangam, with the mythical Sarasvati. The Kumbh Mela is held here.
• Kanpur (Jajmau): centre of factory pollution.
• Farakka (West Bengal): the river splits [2].

• Sagar Island: mouth of the Hugli. The Gangasagar Mela is held here at Makar Sankranti (mid-January).

• Basin location: 22.45°N–31.47°N latitude and 73.37°E–89.31°E longitude [2]. It lies in 11 states/UT: Uttar Pradesh, Uttarakhand, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, Rajasthan, West Bengal, Haryana, Himachal Pradesh and Delhi [2].

• Outside India: Tibet (China) and Nepal in the upper basin [2]. The Padma–Meghna course and the Ganga–Brahmaputra delta are in Bangladesh.
• Cleaning programmes:
• Ganga Action Plan (1985).
• Namami Gange (June 2014), the government's flagship programme. It is run by the NMCG (National Mission for Clean Ganga) under the National Ganga Council.
• Namami Gange is extended to March 2026 with ₹22,500 crore [4].
• It follows the basin plan (GRBMP) made by seven IITs [4].

Don't confuse with

• Bhagirathi vs Alaknanda: Gaumukh (Gangotri glacier) is the source of the Bhagirathi. The Alaknanda rises in the Satopanth glacier above Badrinath.
• Devprayag vs Gangotri/Haridwar: the name "Ganga" starts at Devprayag. Gangotri is the glacier source of the Bhagirathi. Haridwar is where the river enters the plains.
• Padma vs Hugli mouth: the Hugli reaches the sea at Sagar Island in India. The Padma flows into Bangladesh and reaches the sea as the Meghna.
• Triveni Sangam (Prayagraj) vs Harike (Punjab): Triveni is where the Ganga and the Yamuna meet. Harike is where the Beas joins the Satluj, and it has a wetland.

Prelims Hooks

• Panch Prayag, upstream to downstream: Vishnuprayag (Dhauliganga) → Nandprayag (Nandakini) → Karnaprayag (Pindar) → Rudraprayag (Mandakini) → Devprayag (Bhagirathi).
• 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 Sarda (Kali) forms the India–Nepal border.
• Son is the major right-bank tributary (from the Amarkantak plateau). Chambal and Betwa join the Yamuna, not the Ganga [3].
• The Ganga splits at Farakka into the Bhagirathi–Hugli and the Padma [2]. The basin is India's largest but its second most water-stressed, after the Sabarmati [4].
• Dates:
• Ganga Action Plan: 1985
• National River: 2008
• Gangetic dolphin as National Aquatic Animal: 2009. It is an indicator species, meaning its health shows the river's health.
• Namami Gange: June 2014

Mains Points

• Retreating glaciers threaten the Ganga's dry-season flow (GS-I/III)
• Warmer temperatures melt more ice than new snow replaces, so the Gangotri snout moves up the valley.
• Less meltwater reaches the river in the lean season (the dry months before the monsoon). This puts irrigation, drinking water and dams such as Tehri at risk.

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

• Himalayan left-bank tributaries make the plains both fertile and flood-prone (GS-I/III)

• The Kosi and the Gandak carry heavy silt from young mountains. The silt raises their beds, so they spill and shift course, flooding north Bihar.
• The same silt renews the fertile alluvial soil (soil laid down by rivers).

• The basin gets 35.5% of India's rainfall but supports about 47% of its people, so water per person stays low [4].

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

• The Ganga Action Plan (1985) led on to Namami Gange (2014), which uses the IIT-made GRBMP. This approach is called Integrated River Basin Management [4].
• Its goals are Aviral Dhara (continuous flow) and Nirmal Dhara (unpolluted flow) [4].
• Progress by January 2025: 127 STPs (sewage treatment plants) were working, with 3,446 MLD (million litres per day) of capacity, and 33,024 ha had been planted with trees [4].
• Problems that remain: the gap between sewage produced and sewage treated, factory pollution (the Jajmau CETP at Kanpur) and barrages that cut flow and harm dolphin habitat.

Related concepts

• Bhagirathi river
• Gangotri Glacier
• Alaknanda river
• Panch Prayag
• Confluence
• Ganga basin
• Padma river
• Sagar Island

Read more

• The Ganga system: headwaters, main stem and delta