3. The River Brahmaputra

The River Brahmaputra is one of the mightiest rivers in the world. Its water rise more than 5000 meters up the Tibetan Plateau and flow for about 3000 km through , and Bangladesh before joining the Ganges and emptying into the Bay of Bengal. The River has originated from the Angsi Glacier on the northern side of Himalayas which is popularly known as Tsangpo in its upper course and by Chinese name as ‘Yarlung Zangbo’. Both from left and right sides many tributaries have joined Tsangpo to flow down to India. The Brahmaputra has entered India through the state of where it has been called as Siang. As it goes down from the hills to the plain areas it has changed its name to Dihang. In two tributaries such as and Lohit River have joined Brahmaputra one after another and converted Brahmaputra into a very wide river. At certain places it is as wide as 10 kms. Brahmaputra flows down in Assam from east to west over a length of approximately 650 km. As the River passes through the valley of Assam many Himalayan streams including Subansiri, Kameng, Bhareli, Dhansiri, Manas, Champamati, Saralbhanga, and Sankosh rivers have joined Brahmaputra and made it too mighty. The main tributaries from the hills and the plateau to the south are the BurhiDihing, Disang, Dikhu and Kopili. The River has been divided into two channels between Dibrugarh and Lakhimpur districts. In the northern side it is known as Kherkutia and in its south it is known as Brahmaputra channel. After going down about 100 km these two channels have joined together to create the Majuli Islands which is the largest river islands in the world. Then the River passes through Meghalaya to finally merge with Bay of Bengal through Bangladesh. In the course of its journey, the Brahmaputra receives as many as 22 major tributaries in , 33 in India and 3 in Bangladesh. With an average annual discharge of 19,830 cubic metres per second at its mouth, the Brahmaputra ranks fourth among the large rivers of the world.

Goswami (2014) in his article has presented a plethora of information on Brahmaputra. The author has dealt with different dimensions pertaining to the river such as its properties, about the people inhabiting its basin, the economic potential of the river, its potential as an important waterway and with much other information. According to him the River has a 580,000 sq. km basin spread over four neighbouring countries such as China (50.5%), India (33.6%), Bangladesh (8.1%) and Bhutan (7.8%). The Indian part of the basin is shared by Arunachal Pradesh (41.9 %), Assam (36.3%), Meghalaya (6.1%), Nagaland (5.6%), Sikkim (3.8%) and West Bengal (6.3%). Annual average rainfall in the basin excluding Tibetan portion is of 230 cm. Due to strong earth quake in 1897 and 1950 of Richter magnitude 8.7, the course of river changed. Particularly the earthquake of 1950 raised the bed level of the river at Dibrugarh by at least three metres leading to increased flood and erosion potential of the river. In the aftermath of the Great Earthquake of 1950, the damage potential, intensity and frequency of floods have increased significantly. Assam has experienced major floods in the years 1954, 1962, 1966, 1972, 1977, 1984, 1986, 1988, 1998, 2000, 2002 and 2004, 2007, and in 2008 with a reduction in area from 1246 sq. km in 1950 to 875 sq. km in 1998.

The River is lifeline to millions of people. Not only it delivers vital nutrients to the plains of Assam but also causes widespread misery to the people. It has earned notoriety for the awesome hazards of annual flood and erosion that create mayhem every year, bringing misery to the people and shattering the fragile agro-economic base of the region. When the water cascades down from the mountain to the soft alluvial soil of Assam it damages banks of the River. As a result thousands of acres of cultivable lands are lost. Besides it deposits tons of sands on nearby cultivable lands making it less fertile or unusable by the farmers. Due to this many farmers have become landless and have been forced to migrate to different parts of the country in search of alternative source of livelihood. It has been experienced that flood occurs almost every year in one or other part of the lower basin in Assam with varying frequency and magnitude. This occurs particularly in the monsoon season from the month of June up to October. Due to frequent flood of violent nature many houses, properties and community infrastructure are damaged on regular basis and there is loss of human life and cattle.