Perennial river systems originating from the snow-clad Himalayas, featuring antecedent drainage and massive gorges.
- Ganga River System: Originates as Bhagirathi from Gangotri Glacier; joins Alaknanda at Devprayag to form the Ganga. Total length is approx. 2,525 km, with maximum length flowing through Uttar Pradesh.
- Yamuna River System: Longest and westernmost tributary of the Ganga, originating from Yamunotri Glacier on Bandarpunch peak. Meets Ganga at Triveni Sangam in Prayagraj.
- Brahmaputra River System: Originates from Chemayungdung glacier near Mansarovar lake in Tibet (known as Yarlung Tsangpo). Enters India in Arunachal Pradesh as Dihang.
- Indus River System: Flows west-northwest between the Ladakh and Zanskar ranges. Major tributaries include Jhelum, Chenab, Ravi, Beas, and Sutlej governed by the Indus Waters Treaty (1960).
- Major Left Bank Tributaries of Ganga in UP: Includes Ramganga, Gomti, Ghaghra, Gandak, and Kosi. Gomti originates from Gomat Taal (Fulhar Lake) in Pilibhit district, Uttar Pradesh.
| River Name | Origin Point | Outfall / Mouth |
|---|---|---|
| Ganga | Gangotri Glacier (Uttarakhand) | Bay of Bengal (via Padma) |
| Yamuna | Yamunotri Glacier (Uttarakhand) | Prayagraj, Uttar Pradesh |
| Ghaghra | Mapchachungo Glacier (Tibet) | Ganga at Chapra, Bihar |
| Kosi | Gosainthan Peak (Tibet) | Ganga near Kursela, Bihar |