As the interest in long-term modelling of sediment transport and morphodynamics in environmental flows increases due to concerns such as climate change and increasing human pressure, more emphasis has to be put on the understanding and modelling of the basic, though complex, physical processes involved. Sediment transport and morphodynamics are of crucial importance for many environmental and coastal engineering applications, and much advancement has been achieved in these areas. However, the effect of barotropic vortices has been seldom studied despite their ubiquity and importance in environmental flows like rip currents, flows in tidal basins, and flows behind solid obstacles such as piers and embankments. A comprehensive study is proposed to produce a complete and coherent theory of sediment transport by vertical vortices. Such structures have particular signatures and effects that must be understood to better model the erosion/transport/deposition of sediment in coastal areas. Without a better formulation of sediment dynamics, and in particular, the inclusion of barotropic vortex dynamics, the predictive capabilities of state-of the-art models will remain limited and the societal/governmental needs for prediction of changes due to human intervention might not be met. I propose to study well-controlled generic flow configurations that will allow us to model and understand several environmental situations. The proposed approach is composed of state-of-the-art laboratory experiments, direct numerical simulations, and numerical simulations using coastal ocean models. It is only through such a comprehensive approach that well known difficulties, like the scaling experimental results to real-world flows, can be tackled and a complete theory from small-scale laboratory experiments to the large-scale ocean can be achieved. This research and its results will be used to test and improve sediment transport and bed composition modules in coastal ocean models.