(1) The Ganga
The Ganga is formed by the confluence of the Alaknanda and Bhagirathi at Devaprayag. The other source rivers of Alaknanda are Vishnu Ganga and Dhauli Ganga which meet at Vishnuprayag.
The Mandakini meets Alaknanda from the west at Rudra Prayag and the Pindar from the cast at Karan Prayag. The Alaknanda, the main source river rises from a height of 7,800 m in Tibet. Bhagirathi is the main Ganga which rises from the Gangotri glacier at a height of 6,600 m.
The river meets the Bay of Bengal in a delta called Sunderbans. The main tributaries of the Ganga are the Yamuna, Sone, Punpun, etc. as the right tributaries. The left tributaries are the Ramganga, Gomti, Ghaghra, Gandak, Kosi and Mahananda.
Its total length is 2,525 km. Its longest section (1,450 km) lies in Uttranchal, 455 km in Bihar and 520 km in W Bengal. Its total catchment area is about one million sq km.
After Farakka, the Ganga enters Bangladesh and is called Padma. Its one branch which flows in W Bengal is called Bhagirathi- Hooghly.
Some of its tributaries in W Bengal are Damodar, Dwarka, Ajay, Mayurakshi, Roopnarayan and Haldi.. The Yamuna, the main branch of the Brahmaputra meets Padma and later Meghna meets downside.
(2) The Yamuna
This river rises from the Jamnotriglacier near the hot water spring at a height of about 6,000 m. It meets the Ganga at Allahabad. It is the most important tributary of the Ganga.
Its length is about 1,300 km and a catchment area of about 3, 59,000 sq km. Its major tributaries are the Chambal, Kali Sindh, Betwa and Ken.
The Western Yamuna canal gets water from the Yamuna. It has a great irrigation potential. A number of urban centres draw water for drinking purposes from this river.
(3) The Ramganga
This river is the left bank tributary of the Ganga. It rises near Naini Tal in the Lower Himalayas. It has a length of 690 km and a catchment area of 32,800 sq km. It meets the Ganga near Farrukhabad. It is flooded near its confluence with the Ganga.
(4) The Gomti
This is the only tributary river of the Ganga which rises in the plains and not the hills. It meets the Ganga down Varanasi.
(5) The Ghaghra
This river raises parallel to the Ganga in Uttranchal. Its source is in the snowclad Himalayan foothills. It joins the Ganga near Chapra.
It is 1,080 km long and its catchment area is 1, 27,500 sq km. It has two main tributaries – Sarda River, the right bank and Rapti, the left bank tributary.
(6) The Gandak
This river rises in Central Himalayas. It is called the Narayani River in Nepal. It is 425 km long and drains 45,800 sq km. out of which the catchment in India is 9,540 sq km. It causes floods in the U.E and Bihar border areas. The Gandak meets the Ganga near Bankipur in Bihar.
(7) The Burhi Gandak
This river rises in Nepal on the western slopes of Sumesar Hills. Its length is 610 km and drains an area of 12,200 sq km. It joins the Ganga in Bihar after Monghyr. It creates flooding in Bihar.
(8) The Kosi
This river rises in the snow clad mountains of Tibet, Nepal and Sikkim. It flows in three streams in the head reaches. The three streams arc Kosi, Aran and Tamur. Out of this, the Arun is an antecedent river.
Its source is north of Mt Everest. It flows to the east of Everest and the Makalu. The river kosi is 730 km long and drains an area of 86,900 sq km. It creates so much havoc by causing floods that it is called ‘Kosi’- the curse.
This river also changes its course and brings about great destruction. It has shifted nearly 112 km towards the west in the last 200 years.
(9) The Mahananda
It is the eastern most tributary of the Ganga. It is about 290 km long and its catchment area is 25,100 sq km. It creates hell when it is in flood.
(10) The Damodar
This river rises in the hills of Chotanagpur Plateau in Hazaribagh district at an elevation of 1,336 m. It flows in the south-eastern direction. Its total length is 541 km and drains an area of22, 000 sq km.
It meets the Hooghly, an estuary of the Ganga, 48 km below Kolkata. It is known as a flashy river. It creates sudden floods. The main cause of the flood is the westward direction of the rain storm emanating from the Bay of Bengal.
This direction is opposite to the direction of the flow of this river. This makes the water of the Damodar cross its sides and overspill in the adjoining areas.
This river is known as sorrow of Bihar. The Damodar has been tamed with the construction of Damodar Valley project.
(11) Other Flashy Rivers
There are other flashy rivers which join Bhagirathi-Hooghly branch of the Ganga. These are the Ajay, Mayurakshi, etc. These are small rivers on which dams have been constructed to tame them.