A STUDY ON SILT LOAD ON RIVER BRAHMAPUTRA AND SOME OF THE MAJOR TRIBUTARIES IN LOWER ASSAM

Abstract: Sediment is a naturally occurring material that is broken down by processes of weathering and erosion and is subsequently transported by the action of wind, water or ice or by the force of gravity acting on the particles. Stronger flows will increase the lift and drag on the particle, causing it to rise, while larger or denser particles will be more likely to fall through the flow. The rate of sediment transport is associated to several variables such as water discharge, average flow rate, stream power, energy slope, shear stress, water depth, particle size, water temperature, and strength of turbulence. Throughout the low transport stages, particles move by sliding and rolling over the surface of the bed. With the increase of the velocity, the sediment is entrained into suspension and travels significant distances before being deposed again. This report discusses about the effect of silt on Brahmaputra River in lower Assam by taking the sample using depth integrating sampler technique from different location on river Brahmaputra and its tributaries at different depth during the period of autumn and rainy season. Sediments were separated from the collected samples by the process of filtration in the laboratory. Aim of this study is to analyse the variation of sediment load at shallow depth & contribution of some of tributaries to the river Brahmaputra.

Keywords: Sediment movement, silt, discharge, sliding and rolling, Brahmaputra River