3. The Brahmaputra River

Originating from the glaciers lying to the east of the Mansarovar Lake, at an elevation of 5150 m, the Brahmaputra is known as the Tsangpo in Tibet. It pierces the Greater Himalayas (7755 m) near Namcha Barwa. It passes the Dihang-Gorge in Arunachal Pradesh. At Sadiya, the river comes down to 135 m above sea level.

In India, the river is known as Brahmaputra. The river flows to the west in Assam upto Dhubri (28 m), and further below, it takes a sharp southward bend to enter into Bangladesh.

The catchment area of the Brahmaputra receives heavy rainfall. Consequently, it has numerous tributaries on both of its banks in the 750 kilometre long Assam Valley. Most of the tributaries are large and pour large quantity of water and sediment into the Brahmaputra River. During the rainy season, the river oscillates from one bank to other for a width of 10 kilometres (on an average), and being turbulent with heavy loads of silt, the channel is heavily braided. There is a constant silt movement resulting in the instability of river regime, channel shifting and formation of sandy shoals, Majuli, the largest river island in Asia, lies in this river which is bounded by the Lakhimpur District in the north and the Jorhat District in the south. The Brahmaputra river basin is notorious for flooding and river bank erosion. The floods affect on average, an area of 100,000 hectares annually. The peak annual discharge at Pandu, near Guwahati, is more than 2.5 million cusecs (650,000 cumecs), while the low discharge is 120,000 cusecs (4210 cumecs). Below Pasighat, the river draws a number of tributaries such as Subansiri, Bhareli, Manas, Sankos, Tisla and Raidak on its right bank, while the Dihang, Lohit, and Burhi Dihang are from the east, and Dhansiri, Kalang and Kapili are the left bank tributaries of the Brahmaputra.