The Ganges

The Ganges is the most sacred river in Hinduism and one of the most important rivers in the world by the sheer number of people who depend on it. Over 400 million people live in the Ganges basin in India and Bangladesh, more than live near any other river. The Ganges flows for around 2,525 km from the Himalayan glaciers to the Bay of Bengal.

• Length2,525 kmLong but not as long as the Nile or Amazon
• Countries2India and Bangladesh
• SourceGangotri GlacierHigh in the Indian Himalayas
• MouthBay of BengalThrough the Sundarbans, the largest mangrove forest
• People in basinapprox. 400 millionMore than any other river basin
• Sacred toHindusA goddess called Ganga personifies the river

The Ganges compared to other great rivers

Length (km)

Nile6,650

Amazon6,400

Yangtze6,300

Mississ.6,275

Ganges2,525

The Ganges is not the longest river, but it supports more people than any other river basin in the world.

What is the Ganges?

The Ganges (called Ganga in India) flows from the high glaciers of the Himalayas southeast across the flat plains of northern India, then enters Bangladesh, joins with the Brahmaputra River, and pours into the Bay of Bengal through a vast delta. Along its length sit some of the most populous cities on Earth, including Kanpur, Allahabad, Varanasi, Patna and (in Bangladesh) Dhaka. The river is the lifeblood of the great Gangetic Plain, one of the most fertile agricultural regions in the world.

Why is it sacred?

For Hindus, the Ganges is not just a river but a goddess called Ganga. Bathing in the Ganges is believed to wash away sins and bring people closer to spiritual liberation. Dying near the Ganges, or having ashes scattered in it after cremation, is considered the holiest possible end of life. Millions of pilgrims come to the river every year. The Kumbh Mela festival, held every 12 years where the Ganges meets two other rivers at Allahabad, is the largest peaceful gathering of humans on Earth: around 50 million people may attend over the course of the festival.

Fact The city of Varanasi on the banks of the Ganges is considered one of the oldest continuously-inhabited cities in the world, with around 3,500 years of history. The riverfront ghats (stone steps leading down to the water) of Varanasi have been the most sacred Hindu site for over 2,500 years.

The pollution crisis

The Ganges is also one of the most polluted rivers in the world. Vast amounts of untreated sewage, industrial waste, and rubbish enter the river every day. Religious offerings, plus partly-cremated bodies and ashes, add their own complications. In some stretches the bacterial count is over a thousand times higher than is safe for swimming, let alone drinking. Yet millions of people still drink the water and bathe in it daily.

The Indian government has been trying to clean up the Ganges for decades. The latest effort is the Namami Gange programme, launched in 2014 with a multi-billion-dollar budget to build sewage treatment plants and clean up the river. Progress has been slow but the river is now cleaner in some sections than it was a decade ago.

Wildlife of the Ganges

Despite the pollution, the Ganges still has unique wildlife. The Ganges river dolphin is a freshwater dolphin found only here and in nearby rivers. It is almost blind (the muddy water makes eyesight useless) and navigates by sound. There are also fewer than 4,000 left in the wild. The huge mangrove forests of the Sundarbans Delta, where the Ganges meets the sea, are home to one of the last populations of Bengal tigers, plus saltwater crocodiles and several species of dolphin.

Did you know? The Ganges has unusual self-cleaning properties. The water contains naturally-occurring bacterial viruses called bacteriophages that kill some harmful bacteria. Scientists have studied this for over a hundred years and it is part of why the polluted river does not cause even more disease than it does.

Deeper dive: the Gangetic Plain, monsoon dependence and glacial melt

The Gangetic Plain, the flat lowland the river crosses, is one of the largest and most fertile agricultural regions on Earth. The plain stretches over 250,000 square km across northern India and Bangladesh and was built up over millions of years by sediment carried down from the rising Himalayas by the Ganges and its tributaries. The fertile alluvial soil supports two crop seasons a year, growing rice, wheat, sugarcane, jute and pulses for nearly half a billion people. The plain is the historical heartland of Indian civilisation; the ancient kingdoms of the Mauryan, Gupta, and Mughal empires were all centred here.

The Ganges depends heavily on the monsoon. About 80% of the river's annual flow arrives during the four-month monsoon season from June to September. The rest of the year the river runs much lower, sometimes too low to navigate. Climate change is affecting the monsoon: rainfall is becoming more variable, with both more droughts and more devastating floods, making water management more difficult.

The Ganges also depends on Himalayan glaciers for the steady year-round portion of its flow. The Gangotri Glacier and others provide meltwater throughout the dry season, allowing rivers like the Ganges and the Yamuna to keep flowing even when there is no rain. These glaciers are now retreating at around 20 metres per year due to climate change. In the short term, faster melt means more water in the river. In the long term, the loss of the glaciers will mean far less dry-season water and a heavier dependence on the unpredictable monsoon. The Ganges basin is therefore one of the most climate-vulnerable river systems in the world.

The country is India. The other vast Asian river is the Yangtze in China.