Effect of Variation of Inter-Particle Distance on the Erodibility of a Riverbank under Cohesive and Viscous Forces

The riverbank erosion mechanism is very complex, and sediment particles on the riverbank are subjected to a number of forces. Among those forces, the force of cohesion between the particles plays a very significant role. Also important is the viscous force coming into play due to the presence of water-bridge between each pair of particles. Frequency of bank failure is proportional to the erosion rate and bank failure causes flood. Every particle is surrounded by a family of similar particles, and all are bound together under this force of cohesion. In this paper, a recently published analytical model named the ''Truncated Pyramid Model'' for the arrangement of particles has been used, and the general equations for the impending acceleration, as well as the escape velocity, of a particle have been modified to accommodate the viscous force. The effect of the forces on a soil particle is presented graphically for pure water. The graphs depict the deviation from results of the previously published research work due to the consideration of the viscous force. The escape velocity of a particle is the key to determining the other parameters related to riverbank erosion, such as the entrainment rate and the volumetric rate of bank erosion.