EFFECT OF SUSPENDED SEDIMENT ON BED EVOLUTION IN A MEANDERING RIVER OF THE BOLIVIAN AMAZON

Abstract

 This study analyzes the effect of suspended sediment transport on the bed evolution of a suspended load dominated meandering river by using a two-dimensional (2D) numerical model. The numerical simulations were performed under steady and unsteady flow conditions using bathymetric data and in situ sediment samples. The erosion rate was calculated using a turbulent entrainment equation for fine particles. The results showed active changes in the riverbed when suspended sediment was considered in terms of changes in the riverbed profiles and cross sections. For the steady case, erosion was predominant in areas near the inflection points due to topographic features (narrower width and cross-sectional area) which led to active sediment erosion together with a phase-shifting in deposition patterns. Complex changes were observed for the case of unsteady flow that are caused partly by the non-equilibrium nature of suspended sediment.