Sediment mixtures, coastal bedforms and grain sorting phenomena: An overview of the theoretical analyses

Recent studies, which investigate the processes leading to the formation of rhythmic morphological features in the coastal region, are reviewed. Emphasis is given to morphodynamic stability analyses which consider the presence of a heterogeneous sediment. The selective transport of the different fractions of a sediment mixture leads to grain sorting phenomena, which significantly affect the dynamics of the bottom forms. Small scale bedforms (ripples), intermediate bedforms (sorted bedforms and tidal dunes) and large scale bedforms (shoreface-connected ridges and sand banks) are considered. References are given to papers describing the new aspects of the stability analyses arising from the simultaneous presence of a time-dependent forcing flow and a sediment mixture.