Video observations of crescentic sandbar formation and modelling implications

The development of surf zonc crescentic sandbars has beeo analyzed using video observations al lhrce sites: Duck (USA), Gold Coast (Australia). and NoordwiJk (The Netherlands). Video observations indicate the developmenl of crescentic bars is related to non linear dynamics involving merging and spliuing of individual crescents as well as substantial changes in the alongshore spaciog of crescenlic fealures. Observalions have beeo co·mpaced with a numerical model based on (he discretization of the n~>nlinear shallow water equations and a simplified sediment transport fonnulation. Comparisons are Iimited by the difficuhy of includmg in the model al1 of (he physical processes (hat in the field mighl be important. Nevertheless, this work stimulates improvements in surf zone numerical modeling and provides new research dircctions