Exchanges at the bed sediments-water column interface
Interactions at the interface between bed sediments and the overlying waters have a tremendous importance for diverse natural and man-made processes such as fining and armouring in rivers, erosion/sedimentation in bays, and the cycling of different contaminants in water bodies at large. This chapter benefits from a focus on the interface of bed sediments and water to present and discuss the vast area of phenomena related to the transport of sediment particles and contaminants in water resources. We start by presenting the “modes” of sediment transport and follow with the discussion of the concept of incipient motion and the mass balance of solids at the interface – the Exner Equation. We then turn to predictors of different variables needed for the mass balance, such as bed load flow rates, entrainment functions, and the settling velocity. We continue with the theory of suspended sediment and of bed load, exposing separate and consistent treatments. Next section addresses the problem of sediment-laden transport of contaminants in water bodies. The chapter closes with an evaluation of future work in this important subject.