Ganges Riverriver, Asia Hindi Gaṅgā,

The Ganges rises in the southern Himalayas on the Indian side of the Tibet border. Its five headstreams—the Bhāgīrathi, Alaknanda, Mandākini, Dhaulīganga, and Pindar—all rise in the Uttarakhand region (the northern mountainous districts), a division of the state of Uttar Pradesh. Of these, the two main headstreams are the Alaknanda (the longer of the two), which rises about 30 miles north of the Himalayan peak of Nanda Devi, and the Bhāgīrathi, which originates about 10,000 feet (3,050 metres) above sea level in an ice cave at the foot of the Himalayan glacier known as Gangotri. Gangotri itself is a sacred place for Hindu pilgrimage. The true source of the Ganges, however, is considered to be at Gaumukh, about 13 miles southeast of Gangotri.

After the Alaknanda and Bhāgīrathi unite at Devaprayāg, they form a main stream known as the Ganga, which cuts through the outer (southern) Himalayas to emerge from the mountains at Rishikesh. It then flows onto the plain at Hardiwār, another place held sacred by the Hindus.

Although there is a seasonal variation in the river’s flow, its volume increases markedly as it receives more tributaries and enters a region of heavier rainfall. From April to June the melting Himalayan snows feed the river, while in the rainy season from July to September the rain-bearing monsoon winds cause floods. Within the state of Uttar Pradesh, the principal right bank tributaries are the Yamuna River that flows past Delhi, the capital of India, to join the Ganges near Allahābād and the Tons that flows north from the Vindhya Range in the state of Madhya Pradesh and joins it soon after. The main left-bank tributaries in Uttar Pradesh are the Rāmganga, the Gomati, and the Ghāghara.

The Ganges next enters the state of Bihār, where its main tributaries from the Himalayan region to the north are the Gandak, the Burhi Gandak, the Ghugri, and the Kosi and its most important southern tributary is the Son. The river then skirts the Rājmahal Hills to the south and flows southeast to Farakka, at the apex of the delta. In West Bengal, the last Indian state that the Ganges enters, the Mahānanda joins it from the north. (Throughout West Bengal in India, as well as in Bangladesh, the Ganges is locally called the Padma.) The westernmost distributary of the delta is the Hooghly (Hugli), on the east bank of which stands the city of Calcutta. The Hooghly itself is joined by two tributaries flowing in from the west, the Dāmodar and the Rūpnārāyan. In Bangladesh the Ganges is joined by the mighty Brahmaputra (which for about 150 miles before the junction is called the Yamuna) near Goalundo Ghāt. The combined stream, now called the Padma, joins with the Meghna River above Chāndpur. The waters then flow to the Bay of Bengal through innumerable channels, the largest of which is known as the Meghna estuary.

Dhākā (Dacca), the capital of Bangladesh, stands on the Buriganga (Old Ganges), a tributary of the Dhaleswari. Apart from the Hooghly and the Meghna, the other distributary streams that form the Ganges delta are, in West Bengal, the Jalangi and, in Bangladesh, the Mātābhānga, the Bhairab, the Kabadak, the Garai-Madhumati, and the Ariāl Khān.

The Ganges, as well as its tributaries and distributaries, is constantly vulnerable to changes in its course in the delta region. Such changes have occurred in comparatively recent times, especially since 1750. In 1785 the Brahmaputra flowed past the city of Mymensingh; it now flows more than 40 miles west of it before joining the Ganges.

The delta, the seaward prolongation of silt deposits from the Ganges and Brahmaputra river valleys, covers an area of about 23,000 square miles (60,000 square kilometres) and is composed of repeated alternations of clays, sands, and marls, with recurring layers of peat, lignite, and beds of what were once forests. The new deposits of the delta, known in Hindi and Urdu as the khādar, naturally occur in the vicinity of the present channels.

The southern surface of the Ganges delta has been formed by the rapid and comparatively recent deposition of enormous loads of silt. To the east the seaward side of the delta is being changed at a rapid rate by the formation of new lands, known as chārs, and new islands. The western coastline of the delta, however, has remained practically unchanged since the 18th century.

The rivers in the West Bengal area are sluggish; little water passes down them to the sea. In the Bangladeshi delta region, the rivers are broad and active, carrying plentiful water and connected by innumerable creeks. During the rains (from June to October) the greater part of the region is flooded to a depth of several feet, leaving the villages and homesteads, which are built on artificially raised land, isolated above the floodwaters. Communication between settlements during this season can be accomplished only by boat.

To the seaward side of the delta as a whole there is a vast stretch of tidal forests and swampland. The forests, called Sundarbans, are protected by India and Bangladesh for conservation purposes.

In certain parts of the delta there occur layers of peat, composed of forest vegetation and rice plants. In many natural depressions, known as bīl, peat, still in the process of formation, has been used as a fertilizer by local farmers, and it also has been dried and used as a domestic and industrial fuel.