Dynamics of the Sand Particles

Tide and waves redistribute sediment that is placed at the coast. This holds especially for a large-scale nourishment like the Sand Motor. However, not all of these sand grains are transported at the same pace. Fine grains typically move much faster than the coarse grains, but the dynamics of sand particles along exposed beaches are not well understood. Some studies have even argued that the coarser grains are more exposed to the flow and therefore more easily picked up than the fine grains. As most of these studies took place in a laboratory, it would be useful to see evidence of this behavior in the field. If the fine and coarse sand grains move differently, then areas with a coarser or finer bed composition will develop, as sand is removed from some regions and accumulates in others. In this sense, the Sand Motor can be seen as a big sandsorting machine, which can provide us with fundamental understanding of the dynamics of sand grains. Such knowledge is essential if we are to protect and manage the coast in the future. This is particularly important to manage and protect fish populations, since changes in the composition of the sandy bed affect their habitat. For example, juvenile flatfish are known to favor the fine sand over coarser sand, since they can more easily hide from predators (Page 119).