If there is an inlet, longshore transport will build a spit across the opening. If the spit closes the inlet completely, it is called a baymouth bar . Beach nourishment is nothing more than the dumping of sand on to a beach to replace sand that washes away in the surf. Miami beach and many of the beach resorts in Hawaii have resorted to this practice. The sand may be dredged from offshore or it may be trucked in from more distant locations.
Tides rise and fall as a point on earth is rotated through ocean water bulges.
Since the lunar effect dominates, high tide is always experienced when the moon is most nearly overhead, and when the moon is most nearly underfoot. The drama of tides and tidal currents are mostly determined by the shape of the coastline. At the Rance Estuary of France, a dam and turbine system generates electricity from the tidal flow. Most places have much milder tides, around 10 feet or so total range.