Morphodynamics of river dunes : suspended sediment transport along mobile dunes and dune development towards upper stage plane bed

Dunes are the most common bedforms present in nearly all fluvial channels. Because of their dimensions, dunes are of central importance in predicting flow roughness and water levels. During floods in several rivers, dunes are observed to undergo an unstable transition regime after which they are washed out in what is called the upper stage plane bed. This morphological evolution of dunes to upper stage plane bed is the strongest bedform adjustment during time-varying flows and is associated with a significant change in hydraulic roughness and water levels. This thesis aims to obtain a better understanding and quantitative data of the flow and sediment transport mechanisms controlling the dune morphology and dune transition to upper stage plane beds.