There are two types of erosion that could move sand along a shoreline:
Water (Hydraulic) Erosion: the process by which water is responsible for moving the sand from one location to another along the shoreline. This type of erosion is associated with the tidal movement of the ocean as well as weather patterns with wind creating different reactions with the body of water.
Wind Erosion: the process by which air/wind moves the sand from one location to another. This type of erosion is based on the weather patterns for that particular area and time of day.