Sediment transport data from the field and laboratory tests are used to gain insight into two fundamental questions. Firstly: What is the relative importance of coexisting waves and currents for the resulting sediment transport? Secondly: Is the influence of grain size as strong as traditional models predict, or is it as weak as the empirical CERC-formula indicates? Wave tank data reveal that the oscillatory velocity will in most cases determine the direction as well as the magnitude of the

more »

... e normal sediment transport, and wave flume data on shore normal transport as well as field data on littoral drift show weaker grain size dependance than traditional sediment transport models predict. It is suggested that wave dominance as well as weak grain size dependence are manifestations of the fact that the dominant transport mechanisms are often more organised than the diffusion process on which many traditional models are based.