Ganga River System: Origin, Tributaries, Yamuna and the Ganga Basin

Ganga River Origin: Gangotri, Bhagirathi and Alaknanda

Gangotri Glacier, Gaumukh and the Bhagirathi Headwaters

The Ganga rises in the Gangotri glacier near Gaumukh, at about 3,900 m, in Uttarkashi district of Uttarakhand. Gaumukh is the snout of the glacier, and from it the river is called the Bhagirathi. It cuts through the Central and the Lesser Himalayas in narrow gorges.

Several small streams join the Bhagirathi in its upper course. Kedar Ganga joins it at Gangotri, Jadh Ganga at Bhaironghati and Asi Ganga at Uttarkashi, and the Bhilangana joins at the site of old Tehri. The second and larger headstream is the Alaknanda, which gathers the Dhauliganga, the Pindar and the Mandakini on its way down.

Alaknanda River and the Panch Prayag

The Alaknanda rises in the Satopanth glacier above Badrinath. On its way down it receives four rivers at four confluences, and with the Bhagirathi's meeting at Devprayag these make the five sacred confluences called the Panch Prayag. The word prayag means a confluence, and each one is also a milestone in the river's descent from the high Himalaya.

• Vishnuprayag: The Dhauliganga joins the Alaknanda, whose upper reach is called the Vishnu Ganga, near Joshimath.
• Nandaprayag: The Nandakini joins the Alaknanda.
• Karnaprayag: The Pindar joins the Alaknanda.
• Rudraprayag: The Mandakini, also called the Kali Ganga, joins the Alaknanda.
• Devprayag: The Bhagirathi meets the Alaknanda, and from this point the river is known as the Ganga.

Devprayag therefore marks the start of the main stem. Upstream there are two headstreams of unequal character, and which of them counts as the true source depends on whether the question is about tradition or about hydrology.

Bhagirathi or Alaknanda: Which Is the Source Stream

Hindu tradition, and the official account of the Ganga's course, treat the Bhagirathi as the source stream of the Ganga. Hydrologists count the Alaknanda instead, because it is longer and carries more water. Measured with its tributaries, the Alaknanda is 664.5 km long and the Bhagirathi 456.5 km. The Alaknanda contributes a much larger share of the Ganga's flow at Devprayag.

By tradition, then, the Ganga rises as the Bhagirathi at Gaumukh, while by length and flow the Alaknanda is the main headstream. Both statements are correct, each under its own definition of source.

Ganga River Course from Haridwar to the Bay of Bengal

Ganga River Length and States It Flows Through

The Ganga is 2,525 km long from Gaumukh to the Bay of Bengal. The length is shared among four states. The river enters the plains at Haridwar, flows first to the south, then to the south-east and east, and finally discharges into the Bay of Bengal near Sagar Island.

Jharkhand is sometimes counted as a fifth main-stem state, because the river flows past Sahibganj on its north-eastern edge.

Uttar Pradesh holds 1,450 km of the 2,525 km, which is more than half of the river's length.

Upper Ganga: Haridwar, the Canals and the Ramganga

At Haridwar the Ganga opens onto the Gangetic plains, and a barrage diverts a large quantity of its water into the Upper Ganga Canal for irrigation. At Bijnor another barrage diverts water into the Madhya Ganga Canal, but only in the monsoon months. At Narora a third diversion feeds the Lower Ganga Canal. The Upper Ganga Canal irrigates the Doab region of Uttar Pradesh, the fertile land between the Ganga and the Yamuna.

The upper river is also regulated far upstream. The Tehri Dam on the Bhagirathi, a 260.5 m rock and earth-fill embankment dam completed in 2006 and the tallest dam in India, was built for hydropower and releases additional water in the dry months.

Further down, the Ramganga joins the Ganga near Kannauj and adds water to the river. Between Haridwar and Prayagraj the river has a problem of low flows, and December to May are its lean months.

Middle Ganga: Prayagraj to Farakka

At the Sangam in Prayagraj the Yamuna meets the Ganga and makes a major contribution to the flow. At the confluence the Yamuna is in fact the larger river, contributing about 58.5 per cent of the combined flow. The Ganga's name survives below the confluence all the same.

Beyond Prayagraj the Ganga is joined by several tributaries, most of them from the north and a few from the south. Between Prayagraj in Uttar Pradesh and Malda in West Bengal the river therefore carries a considerable flow. The northern rivers are the Ghaghara, Gandak, Kosi and Mahananda from the Himalayas and the Gomati from the plains of Uttar Pradesh, and the main southern river is the Son from the Peninsula.

Annual flooding is a characteristic of all the rivers of the Ganga basin. The Ganga rises during the monsoon, but its high banks keep the flood water from spreading very far, and the active flood plain is usually 0.5 to 2 km wide and is flooded every year.

Farakka Barrage: The Hooghly and Padma Distributaries

At Farakka in West Bengal a barrage regulates the flow of the river. It diverts some of the water into a feeder canal that links the Ganga with the Hooghly and keeps that river relatively free of silt. The barrage became operational on 21 April 1975, and the feeder canal is about 42 km long.

Downstream of the barrage the Ganga splits into two. The Bhagirathi-Hooghly branch goes to the right and the Padma to the left. The Hooghly meets the Bay of Bengal about 150 km below Kolkata. The Padma enters Bangladesh, where it is joined by the Jamuna, which is the lower stream of the Brahmaputra, and by the Meghna before reaching the sea.

The Ganga-Brahmaputra-Meghna system formed in this way is the second-largest river system on earth by discharge.

Tributaries of the Ganga River: Left Bank, Right Bank and Rankings

Left Bank and Right Bank Tributaries and the Damodar

A tributary is called a left bank or right bank tributary by the side on which it joins, seen when facing downstream. The system holds both perennial and non-perennial rivers. Its right bank tributaries are the Yamuna, the westernmost and longest, and the Son, and its left bank tributaries are the Ramganga, the Gomati, the Ghaghara, the Gandak, the Kosi and the Mahananda. The Chambal and Betwa are called sub-tributaries because they join the Yamuna and not the Ganga.

The Damodar drains the Chotanagpur Plateau, but it joins the Hooghly, a distributary of the Ganga, and not the Ganga itself.

Himalayan and Peninsular Tributaries Compared

The rivers of the Ganga system fall into two groups by origin. The left bank rivers and the Yamuna rise in the Himalayas. The Chambal, Sind, Betwa, Ken and Son rise in the northern part of the Peninsula and also belong to the Ganga system.

The Yamuna is a Himalayan river that joins on the right bank, and it carries the Peninsular rivers Chambal, Sind, Betwa and Ken to the Ganga. The right bank therefore holds both a Himalayan river and Peninsular ones.

Largest, Longest and Largest by Volume: Ranking the Tributaries

Rankings of the Ganga's tributaries use different measures, and the answer depends on which one is meant. The Yamuna is the longest tributary at 1,376 km. The Ghaghara is the largest by volume of water and the second largest by length, at 1,080 km up to its confluence with the Ganga. The Kosi is the third-largest by discharge, after the Ghaghara and the Yamuna. At Prayagraj the Yamuna carries more water than the upper Ganga, yet over the whole course the Ghaghara brings the largest volume of any tributary. The Son is the largest of the rivers that rise on the Peninsula and join the Ganga directly.

The Yamuna, Son, Ghaghara and Kosi together contribute over half of the annual water yield of the Ganga. These tributaries meet the Ganga at Prayagraj and further downstream.

Left Bank Tributaries: Ramganga, Gomati, Ghaghara, Gandak, Kosi and Mahananda

Ramganga and Gomati: Rivers of Uttar Pradesh

The Ramganga is a comparatively small river that rises in the Garhwal hills near Gairsain. It changes course to the south-west after crossing the Shiwaliks. It flows westward from the Patli Dun valley into the Jim Corbett National Park, and a dam has been built near Kalagarh in Pauri Garhwal district, just before it enters the plains of Uttar Pradesh. It finally joins the Ganga near Kannauj. It adds an average annual flow of about 495 cubic metres per second to the Ganga.

The Gomati is different, because it does not rise in the snow. It begins at the Gomat Taal near Madhotanda in Pilibhit district and is fed by monsoon rain and groundwater. After about 190 km it enters Lucknow and meanders for about 30 km through the city, where 25 city drains pour untreated sewage into it. The Sai joins the Gomati near Jaunpur, and the Markandey Mahadeo temple stands at the confluence of the Gomati and the Ganga.

The two rivers show how left bank rivers differ in character. The Ramganga is a hill river that becomes a plains river after the Shiwaliks, while the Gomati is a plains river from its source.

Ghaghara and Sarda: The Largest Tributary by Volume

The Ghaghara is known as the Karnali in Nepal. It originates in the glaciers of Mapchachungo in Tibet, at about 3,962 m, and flows south through one of the most remote and least explored areas of Nepal. After collecting the waters of the Tila, Seti and Beri, it comes out of the mountains and cuts a deep gorge at Shishapani. Its total length to the Ganga is 1,080 km, and it is the largest tributary of the Ganga by volume. It is a perennial river.

The Sarda joins it in the plain. The Sarda rises in Pithoragarh district of Uttarakhand, on the eastern slopes of the Nanda Devi massif, where it is called the Kali; it forms the Indo-Nepal border and takes the name Sarda when it enters the plains. The Ghaghara, which is called the Saryu in its lower course in Awadh, then meets the Ganga at Chhapra in Bihar.

Gandak: Kali Gandaki and Trishuli from Nepal

The Gandak is formed by two streams, the Kali Gandaki and the Trishuli. It rises in the Nepal Himalayas between Dhaulagiri and Mount Everest and drains the central part of Nepal. Within Nepal the river is known as the Kali Gandaki in its upper reaches, where it flows through a famous gorge in Mustang district. When it reaches the Tarai plains near the Trishuli confluence at Devghat in Chitwan, it is called the Narayani. After it crosses the border it is called the Gandak.

The Gandak enters the Ganga plain in Champaran district of Bihar and joins the Ganga at Sonpur near Patna. The Gandak Barrage at Valmikinagar controls it, and the Valmiki National Park of India lies next to Nepal's Chitwan National Park in the same stretch.

The same river thus carries three names, the Kali Gandaki, the Narayani and the Gandak, one for each stretch.

Kosi and Mahananda: The Sorrow of Bihar and the Last Left Bank River

The Kosi is an antecedent river. Its main stream, the Arun, rises north of Mount Everest in Tibet. After crossing the Central Himalayas in Nepal, it is joined by the Sun Kosi from the west and the Tamur from the east. The combined river is called the Sapt Kosi because seven streams, among them the Arun, the Sun Kosi and the Tamur, meet north of the Chatra Gorge in Nepal. The Kosi then crosses into northern Bihar and joins the Ganga near Kursela in Katihar district. It is 720 km long and drains about 74,500 sq km in Tibet, Nepal and Bihar.

The Kosi is called the Sorrow of Bihar. It brings a huge quantity of sediment from its upper reaches and deposits it in the plains. The course gets blocked, and the river changes its course. Its annual floods affect about 21,000 sq km of fertile agricultural land. On 18 August 2008 the river took up an old channel that it had abandoned more than 100 years earlier, broke its embankment at Kusaha and affected about 2.7 million people.

The Kosi Barrage at Bhimnagar, on the Indo-Nepal border, was built between 1959 and 1963 to hold the river in place. The river had been described as moving about 120 km westward in 250 years, but a review of 28 historical maps from 1760 to 1960 found the shift small and oscillating.

East of the Kosi the Mahananda is the last left bank tributary of the Ganga in West Bengal. It rises at the Paglajhora Falls on Mahaldiram Hill, east of Kurseong in Darjeeling district, at about 2,100 m, and flows past Siliguri before crossing Bihar and West Bengal into Bangladesh.

Son River and the Damodar: Rivers from the Peninsular Plateau

Son River: From Amarkantak to Patna

The Son is a large right bank tributary of the Ganga. It originates on the Amarkantak plateau, and after forming a series of waterfalls at the edge of the plateau it reaches Arrah, west of Patna, to join the Ganga. It is 784 km long, and its chief tributaries are the Rihand, Kanhar and North Koel.

The Son shows the character of the Peninsular tributaries. It has a steep gradient of 35 to 55 cm per km and quick run-off, and it is ephemeral. After rain it becomes a roaring river, and soon afterwards it turns into a fordable stream. Being wide and shallow, it leaves disconnected pools of water in the dry months.

The Bansagar project on the Son is an interstate project of Uttar Pradesh, Madhya Pradesh and Bihar, and the Bansagar Control Board was constituted in 1976 for its early execution.

Damodar River and the Damodar Valley Corporation

The Damodar occupies the eastern margins of the Chotanagpur Plateau, where it flows through a rift valley, and it finally joins the Hooghly. It rises on the Khamarpat Hill in Jharkhand and travels about 592 km. The Barakar is its main tributary. It is a rain-fed river, and its floods once earned it the name Sorrow of Bengal.

The Damodar Valley Corporation (DVC) tamed the river. It was set up in 1948 under the Damodar Valley Corporation Act (Act No. XIV of 1948) as the first multipurpose river valley project of independent India. Bihar, now Jharkhand, and West Bengal took part with the Centre. The Corporation built four multipurpose dams at Tilaiya, Konar, Maithon and Panchet, and the barrage at Durgapur feeds an irrigation canal system. It operates thermal and hydel power stations, and by 1990‑91 it also ran a gas turbine station at Maithon of 3 x 27.5 MW.

Yamuna River: Origin, Course and Tributaries

Yamuna River Origin: Yamunotri Glacier and the Upper Course

The Yamuna is the westernmost and the longest tributary of the Ganga. It rises in the Yamunotri glacier on the western slopes of the Banderpunch range (6,316 m), in Uttarkashi district of Uttarakhand. In its first 170 km the Rishi Ganga Kunta, Hanuman Ganga, Tons and Giri join the main river. The Tons is the largest tributary of the upper catchment and holds more water than the main stream.

The river travels 1,376 km and drains 3,66,223 sq km, about two-fifths of the Ganga basin in India, before it joins the Ganga at Prayagraj. It flows through Uttarakhand, Himachal Pradesh, Haryana, Delhi and Uttar Pradesh. After flowing through the lower Himalayan valleys it emerges onto the Indo-Gangetic plain at Dak Pathar in Uttarakhand, where a weir regulates it and diverts water into a canal for power generation.

At Hathnikund and Tajewala in Yamunanagar district of Haryana its water is diverted into the Western and Eastern Yamuna canals for irrigation. During the dry season no water is allowed to flow down the river below Tajewala, and the river remains dry in some stretches between Tajewala and Delhi. It enters Delhi near Palla village, about 224 km below Tajewala.

Yamuna River in the Plains: Delhi, the Doab and Triveni Sangam

The Yamuna is divided into five segments, from the Himalayan stretch above Tajewala to the diluted stretch below the Chambal confluence.

The 22 km Delhi segment is less than 2 per cent of the river's length but accounts for nearly 80 per cent of its total pollution, because 15 drains discharge wastewater between the Wazirabad and Okhla barrages. Nearly 57 million people depend on the river's water.

Below Delhi the Yamuna flows through the Ganga-Yamuna Doab, a highly fertile alluvial region between the two rivers. The stretch after the Chambal confluence is the diluted segment. The Yamuna then merges with the Ganga at the Triveni Sangam in Prayagraj. Tradition says that the mythical Saraswati also joins there, and the Sangam is a site of the Kumbh Mela.

Yamuna River Tributaries: Chambal, Sind, Betwa and Ken

The Yamuna is joined by the Chambal, the Sind, the Betwa and the Ken on its right bank. These rivers originate on the Peninsular plateau. The Hindan, the Rind, the Sengar and the Varuna join it on its left bank. In the hills the Tons and the Giri join it, and the Tons is its largest tributary by water.

The Chambal is its longest tributary and has a large basin of its own. The Chambal, Betwa and Ken reach the Ganga only through the Yamuna, so they are tributaries of the Yamuna and not of the Ganga.

Chambal, Betwa and Ken: Peninsular Rivers of the Ganga System

The Chambal is 1,024 km long. It rises near Mhow, on the Malwa plateau of Madhya Pradesh, at about 843 m, from the Bhadakla Falls in the Janapav Hills. It flows northwards through a gorge, and the Gandhisagar dam stands on it. From Kota it passes Bundi, Sawai Madhopur and Dholpur and finally joins the Yamuna. It is famous for its badland topography, the Chambal ravines of Bhind and Morena.

The Betwa rises in the Vindhya Range just north of Hoshangabad (Narmadapuram) in Madhya Pradesh and flows north-east, entering Uttar Pradesh after Orchha. The Rajghat dam on the Betwa is an interstate project of Uttar Pradesh and Madhya Pradesh, and the Betwa Board was set up in 1973 for its execution.

The Ken rises near Ahirgawan on the north-west slopes of the Barner Range in Katni district. After 427 km it merges with the Yamuna at Chilla village in Banda district of Uttar Pradesh. On its way it cuts a gorge 60 km long and 150 to 180 m deep in the Bijawar-Panna plateau.

The Ken-Betwa Link Project links two of these rivers. It is a plan to transfer surplus water from the Ken in Madhya Pradesh to the Betwa in Uttar Pradesh and involves the Daudhan Dam. Its stated aim is to irrigate 10.6 lakh hectares in drought-stricken Bundelkhand and to provide drinking water to 6.2 million people.

Ganga Delta and the Sundarbans

Ganga Delta: Extent, Distributaries and Fertility

The Ganga Delta is also called the Ganges-Brahmaputra Delta, the Sundarbans Delta or the Bengal Delta. It is the world's largest river delta, and it covers the Bengal region, which is made up of Bangladesh and the Indian state of West Bengal. It covers more than 1,05,000 sq km and stretches from the Hooghly in the west to the Meghna in the east. Its shape is that of an arc-shaped triangle, and its fertile land has earned it the name Green Delta.

The delta is built by the Ganga and the Brahmaputra together. The Bhagirathi-Hooghly, 408 km long, is the first distributary to branch from the Ganga at Farakka, and the Hooghly flows past Murshidabad, Nabadwip, Kolkata and Howrah before it empties into the Bay of Bengal near Sagar Island. The Hooghly receives the Ajay, Damodar, Rupnarayan and Haldi. The Padma is the eastern and main distributary, which flows generally south-east for 356 km to its confluence with the Meghna.

The mouths of the great rivers of the northern plains form some of the largest deltas of the world, and the Sundarbans is the best-known example.

Sundarbans: The Mangrove Delta of the Ganga

The Sundarbans is a mangrove forest in the Ganga Delta, formed by the Ganga, the Brahmaputra and the Meghna where they meet the Bay of Bengal. It spans the area from the Hooghly in West Bengal to the Baleswar River in Bangladesh. It covers 10,277 sq km and is the world's largest mangrove forest. Of this, 6,017 sq km lie in Bangladesh and 4,260 sq km in the South 24 Parganas and North 24 Parganas districts of West Bengal.

The forest takes its name from the sundri tree, Heritiera fomes, which is the predominant mangrove species. A network of waterways makes almost every corner of the forest accessible by boat. It is known for the Bengal tiger and for crocodiles, birds, chital and snakes. Sundarbans National Park in India is among the protected areas listed as UNESCO World Heritage Sites. The Indian Sundarbans were assessed as endangered in 2020 under the IUCN Red List of Ecosystems framework.

Ganga River Basin: Area, Relief, Soils and Water

Drainage Area by State and Culturable Land

The Ganga basin is the largest river basin in India by catchment area. It lies between 73°02' and 89°05' east longitude and between 21°06' and 31°21' north latitude, and it extends over India, Nepal and Bangladesh with a total area of 10,86,000 sq km. The Indian part is 8,61,404 sq km.

The Ganga sub-basin has a culturable area of about 57.96 million hectares, which is 29.5 per cent of the total culturable area of the country. The Ganga and Yamuna canal systems irrigate vast areas using the perennial flow of the rivers.

Physiography of the Ganga Basin: Mountains, Plain and Plateau

The basin has three large structural divisions, namely the Himalayan fold mountains, the Gangetic plain, and the Central Indian highlands with the Peninsular shield. The Himalayan fold mountains include numerous snow peaks rising above 7,000 m, each surrounded by snowfields and glaciers. The Gangetic plain, in which the main stem lies, is an alluvial formation and a vast, flat, depositional surface below 300 m.

The northern plains built by the Indus, Ganga and Brahmaputra extend about 3,200 km from east to west, their average width is 150 to 300 km, and the alluvium reaches a depth of 1,000 to 2,000 m. From north to south they divide into four zones:

• Bhabar: A narrow belt of 8 to 10 km along the Shiwalik foothills, where streams deposit heavy rock and boulders and at times disappear.
• Tarai: A belt of 10 to 20 km south of the Bhabar, where the streams re-emerge without a demarcated channel and create marshy conditions.
• Bhangar: The older alluvium.
• Khadar: The newer alluvium of the flood plains.

Both the Bhangar and the Khadar show sand bars, meanders, ox-bow lakes and braided channels.

The states of Haryana and Delhi form a water divide between the Indus and Ganga river systems.

Soils of the Ganga Basin

The Ganga basin has a wide variety of soils. The soils of the high Himalayas are subject to continuous erosion. The Gangetic plain is a huge receptacle in which thousands of metres of sediments have been deposited to form a wide valley plain. The Deccan plateau on the south has a mantle of residual soils of varying thickness from the weathering of ancient rocks.

Soils in Haryana, Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal, the states drained by the main stem and its tributaries, have very high erodibility. The five groups together cover 98 per cent of the basin.

Water Resources, Flow and Floods of the Ganga Basin

Rainfall, subsurface flows and snowmelt from glaciers are the main sources of water in the Ganga. Its surface water resources are assessed at 525 billion cubic metres. Each square km of the basin receives on average a million cubic metres of water as rainfall. About 30 per cent of this is lost as evaporation, 20 per cent seeps into the subsurface and the remaining 50 per cent is available as surface run-off.

The Ganga Flood Control Commission was set up in 1972 to prepare a comprehensive flood control plan for the basin, whose rivers flood every year. The important storages in the basin include Matatila, Sarda Sagar, Ramganga, Mayurakshi and the DVC reservoirs. Other projects are Rajghat on the Betwa, Bansagar on the Son and Tehri on the Bhagirathi. The hydropower potential of the basin is 10,715 MW at 60 per cent load factor, and a larger part of it remains to be exploited.

Population of the Ganga Basin: Distribution, Density and Pressure on Water

Population Density of the Plains and the Hill States

The Ganga basin has a population of more than 500 million and is the most populated river basin in the world. It held about 43 per cent of India's people in 2001, although it covers 26 per cent of the land. Its average density was 520 persons per sq km against 325 for the whole country.

The density is highest on the plains. In 2011 the density of Bihar was 1,102, West Bengal 1,029 and Uttar Pradesh 828 persons per sq km, against 382 for India. The hill states of the Himalayan region have low densities. The river valley plains have fertile alluvial soil that supports crops such as wheat, rice, sugarcane and jute, and so a large population.

Land, Soil and Water Behind the Density of the Plains

Land, soil and water together explain why the Gangetic plain is so crowded, and each of the three works through farming.

• Flat land: The northern plains are a featureless plain with a general elevation of 50 to 150 m, flat enough for intensive cultivation. The culturable area of the basin is 29.5 per cent of India's.
• Alluvial soil: The plain is built of deep alluvium, and its soils are fertile when farmed, though loose alluvium, like the mountain soils, erodes easily.
• Assured water: Perennial rivers feed the Ganga and Yamuna canal systems, which irrigate vast areas. The flow becomes lean from December to May.

At the margins of the basin the pattern reverses. Mountain soils erode easily, the plateau to the south has thin residual soils, and the Peninsular side of the basin carries far fewer people per sq km than the plain.

Cities and Urban Growth in the Ganga Basin

The major cities of Delhi, Kolkata, Kanpur, Lucknow, Patna, Agra, Meerut, Varanasi and Prayagraj lie in the basin. Their populations are large and growing, and their industry is expanding quickly. Between 2001 and 2011 the urban population of the basin states increased by about 30 per cent, and the pollution load is expected to increase correspondingly.

Groundwater Depletion in the Gangetic Plain and Food Security

Groundwater beneath the plain is falling fast. Between 2002 and 2008, satellites that sense changes in the Earth's gravity field recorded groundwater levels in northern India falling by as much as 33 centimetres a year, and more than 108 cubic kilometres of groundwater disappeared from aquifers in Haryana, Punjab, Rajasthan and Delhi. Haryana, Rajasthan and Delhi lie partly in the Ganga basin. The loss was almost entirely due to human activity, mainly irrigation, even though rainfall in those years was slightly above normal.

For the 114 million residents of the region the consequences may include a collapse of agricultural output and severe shortages of drinking water. The same plains grow much of India's wheat, rice and sugarcane on irrigated alluvium, so a falling water table is a threat to food security.

For the whole country the 2025 assessment by the Central Ground Water Board puts the stage of groundwater extraction at 60.63 per cent. A block with extraction of 70 to 90 per cent is classed semi-critical, one with 90 to 100 per cent is critical, and one above 100 per cent is over-exploited.

Ganga River Pollution, Namami Gange and Conservation

Pollution of the Ganga River: Sewage and Industrial Effluent

In some stretches, particularly in lean seasons, the Ganga has become unfit even for bathing. About 12,000 million litres a day of sewage are generated in the Ganga basin, against a treatment capacity of only about 4,000 million litres a day. Around 3,000 million litres a day are discharged into the main stem from Class I and II towns on its banks, where treatment capacity of about 1,000 million litres a day has been created.

Industrial pollution is about 20 per cent of the volume, but its toxic and non-biodegradable nature gives it much greater significance. The industrial pockets in the catchments of the Ramganga and Kali rivers and in Kanpur city are significant sources. The major contributors are tanneries in Kanpur, and distilleries, paper mills and sugar mills in the Kosi, Ramganga and Kali river catchments.

Pollution is easing but has not ended. In the 2025 assessment of polluted river stretches, the Ganga has no polluted stretch in Uttarakhand or Jharkhand, while the stretch from Bijnor to Tarighat in Uttar Pradesh remains polluted.

Ganga Action Plan, NGRBA and the National Ganga Council

The Ganga Action Plan was launched by Prime Minister Rajiv Gandhi in June 1985. It covered 25 Class I towns, six in Uttar Pradesh, four in Bihar and 15 in West Bengal, and spent ₹862.59 crore on intercepting, diverting and treating domestic sewage. The Government proposed to extend this model nationally through the National River Action Plan.

The National Ganga River Basin Authority (NGRBA) was established on 20 February 2009 under Section 3 of the Environment (Protection) Act, 1986, and the Ganga was declared the National River at the same time. The Prime Minister chaired it, and its members included the chief ministers of the states through which the Ganga flows. It was a planning, financing, monitoring and coordinating authority with a river basin approach. On 5 October 2009, at its first meeting, it decided to declare the river dolphin the National Aquatic Animal. In 2011 the World Bank approved $1 billion in funding for it.

On 20 September 2016 the Government notified the River Ganga (Rejuvenation, Protection and Management) Authorities Order, 2016, which created the National Ganga Council to replace the NGRBA.

Namami Gange Programme: Pillars, Phases and Progress

The Namami Gange Programme is an integrated conservation mission, approved as a flagship programme by the Union Government in June 2014 with a budget outlay of ₹20,000 crore. Its twin objectives are the effective abatement of pollution and the conservation and rejuvenation of the National River Ganga. Its pillars are sewerage treatment infrastructure, river-front development, river-surface cleaning, biodiversity, afforestation, public awareness, industrial effluent monitoring and Ganga Gram. Its work was divided into first-stage activities for immediate visible impact, medium-term activities of five years and long-term activities of ten years.

Phase I ran up to March 2021. Namami Gange Mission-II, the second phase, was approved in 2023 with an outlay of ₹22,500 crore for the period up to March 2026. In all, 524 projects had been sanctioned and 355 of them, or 68 per cent, had been completed by February 2026. The mission had disbursed ₹21,340 crore between June 2014 and 15 March 2026, of which ₹16,025.97 crore went to sewage treatment projects.

Water quality has improved at several sites. The median faecal coliform count at Assighat in Varanasi fell from 2,500 MPN per 100 mL in 2014 to 790 in 2025.

Earlier efforts to clean the Ganga concentrated on a few highly polluting towns and treated wastewater at the end of the pipe. Three-quarters of all the sewage generated in the northern plains remained untreated, and where sewage plants existed more than half were not operating efficiently. Mission Clean Ganga and then Namami Gange plan for the whole basin instead.

Ganges River Dolphin and Gharial: Threats and Protection

The Ganges river dolphin lives along the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India. It prefers deep pools and eddy countercurrents downstream of confluences and sharp meanders. It uses echolocation because it cannot see well in the cloudy water. It has been an Endangered species on the IUCN Red List since 1996.

The Ganges dolphin was declared India's National Aquatic Animal after the first NGRBA meeting in 2009. It is an indicator species of the health of the river, and it is included in Schedule I of the Wildlife (Protection) Act, 1972, which gives it the highest degree of protection. Surveys covering 8,507 km of 28 rivers put the nationwide population at 6,324. Assessments of gharial across 22 rivers recorded 3,037 individuals.

The main threats are the construction of dams and hydroelectric power plants, habitat fragmentation by reduced dry-season flows, accidental entanglement in fishing nets, and pollution from towns and intensive farming near the rivers.

Sources

• Central Water Commission: Ganga basin
• Central Water Commission: Yamuna Basin Organisation, basin details
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• NCERT: India Physical Environment (Class XI), Drainage System
• NCERT: India People and Economy (Class XII), Population: Distribution, Density, Growth and Composition
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• National Mission for Clean Ganga: Demography
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• National Mission for Clean Ganga: Location
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• Press Information Bureau: Dynamic Ground Water Resources Assessment 2025
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• Wikipedia: Animal Welfare Board of India
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• Wikipedia: Chambal River
• Wikipedia: Damodar River
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• Wikipedia: Farakka Barrage
• Wikipedia: Gandaki River
• Wikipedia: Ganges
• Wikipedia: Ganges Basin
• Wikipedia: Ganges Delta
• Wikipedia: Ganges river dolphin
• Wikipedia: Ghaghara
• Wikipedia: Gomti River
• Wikipedia: Hooghly River
• Wikipedia: Kaziranga National Park
• Wikipedia: Ken River
• Wikipedia: Kosi River
• Wikipedia: Mahananda River
• Wikipedia: National Ganga River Basin Authority
• Wikipedia: National Tiger Conservation Authority
• Wikipedia: Padma River
• Wikipedia: Pollution of the Ganges
• Wikipedia: Ramganga
• Wikipedia: Sharda River
• Wikipedia: Silent Valley National Park
• Wikipedia: Sone River
• Wikipedia: Sundarbans
• Wikipedia: Tehri Dam
• Wikipedia: Triveni Sangam
• Wikipedia: Yamuna
• UPSC: Civil Services Examination question papers