The frequent shifting of the course of the Brahmaputra River in the plains of Assam is mainly due to ____.

The correct answer is heavy deposition of silt that raises the level of the riverbed . Key Points The Brahmaputra River is known as one of the largest braided river systems in the world, particularly in the plains of Assam , where it carries an enormous sediment load . During the monsoon season , the river experiences heavy rainfall in the Himalayan catchment areas , leading to intense soil erosion and high concentrations of suspended solids . As the river enters the flat Assam Valley , the gradient decreases sharply, causing the flow velocity to drop and the heavy deposition of silt on the riverbed. This aggradation (raising of the riverbed level) reduces the channel capacity , forcing the water to cut new paths and resulting in frequent shifting of the course and bank erosion . The region is also tectonically active ; the Great Assam Earthquake of 1950 significantly altered the river's morphology by raising the bed level further through massive landslides and sediment inflow. Additional Information Geographical Context of Brahmaputra : The river originates from the Chemayungdung Glacier in the Kailash Range near Mansarovar Lake , where it is known as the Tsangpo . It enters India through Arunachal Pradesh via a deep gorge at Namcha Barwa and flows through the Assam Valley for about 720 kilometers. The Majuli Island , located in this river, is recognized as the world's largest riverine island , which is also a victim of constant erosion and channel migration . The tributaries like Subansiri , Manas , and Lohit contribute significantly to the discharge and siltation , contradicting the idea of a lack of tributaries. Tidal effects primarily influence the deltaic region in Bangladesh near the Bay of Bengal , rather than the upper plains of Assam .