The Brahmaputra River

The Himalayan rivers deliver about one-tenth of global particulate and dissolved materials to the ocean from only about 1.6% of the global drainage area indicating very high physical and chemical erosion rates and play a dominant role in controlling the sedimentary and geochemical budgets of the global ocean and regulating the global climate. The Brahmaputra River is the most significant among the Himalayan rivers in terms of supply of sediment and dissolved materials. Its 2900-km long stretch and 636 thousand-km² drainage area lies in very contrasting climatic and geological regions. It originates in arid and cold region of Tibet and has significant drainage in warm and heavy precipitating zones such as Mishmi Hills, Naga-Patkoi ranges and the Shillong Plateau. It has very gentle slope in Tibet to very steep slope in the Eastern Syntaxis where it has created deepest (>5000 m) gorge of the world. Both physical and chemical erosions in the basin are highly variable with lower rates in the Tibet to very high around the Eastern Syntaxis. The Eastern Syntaxis seems to be the hot spot of physical and chemical weathering and for associated CO₂ consumption, which are driven by the higher stream power of the Brahmaputra in this region. Intense and focussed erosion in the Eastern Syntaxis generates about half of the total sediment delivered by the Brahmaputra to the ocean. High sediment yield from this region seems to be responsible for the higher peaks of the Namche Barwa and the Gyala Peri and the knick point in the Tsangpo upstream the Eastern Syntaxis due to isostatic rebound.