tidal prism

The term "tidal prism" refers to the volume of water that moves in and out of a coastal bay or inlet during a tidal cycle. This volume is calculated by multiplying the tidal range (the difference between high and low tide) by the area of the coastal bay served by the inlet.1

Tidal currents, driven by the tidal prism, are crucial for sediment transport, particularly in constricted areas like inlets and estuaries. While open coasts typically lack currents strong enough to move sediment, these constricted areas can experience swift tidal currents, sometimes exceeding two meters per second.1

The tidal prism is a key factor in shaping coastal landforms. The ebb and flow of tides distribute wave energy and influence where sediment is deposited or eroded. In areas with large tidal ranges and gently sloping shores, such as tidal flats, the shoreline can shift significantly between high and low tide. Estuaries, where river water mixes with seawater, are also influenced by tidal action, which plays a role in their unique water circulation patterns and high biological productivity.12