Introduction

The Brahmaputra is a Himalayan river originating in the Tibet Autonomous Region (TAR) of China and carrying a large flow. Its flow originates from the Angsi glacier near Mount Kailash at an altitude of 5,300 masl with the name Yarlung- Tsangpo. The river flows for about 1,100 km through the arid and semiarid areas of the TAR and gains its large flow as it crosses the Himalayan crest line and enters the rain- rich south aspect of the mountain. As it descends further, it enters India near the town of Korbo and flows in the Indian state of Arunachal Pradesh as Siang or Dihang. Further downstream, near the town of Sadiya in Assam, three tributaries Lohit, Siang and Dibang meet each other and the combined flow is known by the name Brahmaputra. After crossing the town of Dhubri in Assam, the river enters Bangladesh, where it gets the name Jamuna (Figure 5.1). The Brahmaputra sub- basin1 is taken to be ending at the point of its confluence with Ganga in Bangladesh, little upstream of the town of Goalondo. This sub- basin is part of the Ganges- Brahmaputra- Meghna (GBM) basin, draining the joint flow of the three rivers, to the Bay of Bengal, as lower Meghna, south of the town of Chandpur in Bangladesh (Figure 5.1).

The Brahmaputra sub- basin is a complex drainage system characterized by diversity. It drains parts of southern Tibet, the eastern Himalaya in India, all of the area of Bhutan and a large part of northern Bangladesh. The total drainage area of the subbasin is 580,000 sq. km, of which 50.5 percent is in China, 33.6 percent in India, 8.1 percent in Bangladesh and 7.8 percent in Bhutan (Immerzeel 2008). Along its course from Tibet to Goalondo, it flows across unique and diverse geophysical and environmental settings with local, regional and international significance and implications. In India, the sub- basin is shared by the federal states of Arunachal Pradesh (41.88 percent), Assam 36.33 percent), Nagaland (5.57 percent), Meghalaya (6.10 percent), Sikkim (3.75 percent) and West Bengal (6.47 percent). Like all Himalayan rivers, a holistic perception of the flow of a river should be constituted by water, energy, biodiversity and sediments (webs of rivers). The older engineering perception of rivers as mere stock of water generates great uncertainties in its governance processes.