The Subansiri, Kameng, Dhansiri, Manas and Teesta are the major rivers, joining it from the north and Burhi Dihing, Disang and Kopoli join it from the south. Another important tributary of the Brahmaputra is Lohit. Teesta is also well known for changing its course though it does not do so as frequently as does the Kosi. Earlier Teesta used to join Ganga and now it had become a tributary of Brahmaputra. Teesta drains Sikkim and one of its major tributaries is Rangeet.
Himalayan rivers have their source in snowfields and are thus perennial.
This fact has an important bearing upon the potential of canal irrigation and generation of hydro-electricity in northern region and the peninsular region.