Glossary

The following terms as defined in HEC-18, Section 9.2 are used in this program. Please refer to the figure below for the graphic representation.

Diurnal tide: Tides with an approximate tidal period of 24 hours.

Flood or flood tide: Flow of water from the ocean to the bay or estuary.

Semi-diurnal tide: Tides with an approximate tidal period of 12 hours.

Storm tide: Coastal flooding resulting from combination of storm surge and astronomical tide (often referred to as storm surge).

Tidal amplitude: Generally, half of tidal range.

Tidal cycle: One complete rise and fall of the tide.

Tidal period: Duration of one complete tidal cycle. When the tidal period equals the tidal day (24.84 hours), the tide exhibits diurnal behavior. Should two complete tidal periods occur during the tidal day, the tide exhibits semi-diurnal behavior.

Tidal prism: Volume of water contained in a tidal bay, inlet or estuary between low and high tide levels.

Tidal range: Vertical distance between specified low and high tide levels.

Tides, astronomical: Rhythmic diurnal or semi-diurnal variations in sea level that result from gravitational attraction of the moon and sun and other astronomical bodies acting on the rotating Earth.

Tide Figure