- The headwaters of Ganga are called Bhagirathi. It is fed by the Gnagotri Glacier. It is joined by Alaknanda at Devprayag in Uttarakhand.
- Ganga emerges from the mountains on to the plains at Haridwar.
- Yamuna, Ghaghra, Gandak and Kosi are the major tributaries of Ganga. Yamuna originates from the Yamunotri Glacier in the Himalayas. It meets Ganga at Allahabad.
- Gaghra, Gandak and Kosi rise in the Nepal Himalaya.
- Chambal, Betwa and Son are the major tributaries which come from the peninsular uplands.
- After taking waters from various tributaries, Ganga flows towards east till Farakka (West Bengal). The river bifurcates at Farakka. The Bhagirathi-Hooghly (a distributary) flows towards south to the Bay of Bengal.
- The mainstream flows southwards into Bangladesh; where it is joined by the Brahmaputra. It is known as Meghan; further downstream.
- Finally, the Ganga and the Brahmaputra flow into the Bay of Bengal forming the Sunderban Delta. The total length of Ganga is 2500 km.
The Brahmaputra River System:
- The Brahmaputra rises in Tibet; east of Mansarowar lake. It is a little longer than the Indus. Most of the course of the Brahmaputra lies outside India. It flows eastwards parallel to the Himalayas.
- After reaching Namcha Barwa, it enters India in Arunachal Pradesh through a gorge. It is known as Dihang in this region. It is joined by Dibang, Lohit, Kenula and many other tribuatries and finally forms the Brahmaputra in Assam.
- Unlike other north Indian rivers the Brahmaputra gets huge deposits of silt on its bed. This results in rising of the river bed. It also shifts its channel frequently.