A semi diurnal constituent has two maxima and two minima each constituent day, and its symbol is the subscript 2. See type of tide. The order in which the four tides of a day occur, with special reference as to whether the higher high water immediately precedes or follows the lower low water. The direction towards which the current flows. Shallow water constituents include the overtides and compound tides.
Tidal waves are shallow water waves.
The intersection of the land with the water surface. The shoreline shown on charts represents the line of contact between the land and a selected water elevation. In areas affected by tidal fluctuations, this line of contact is the mean high water line. In confined coastal waters of diminished tidal influence, the mean water level line may be used. See coast line.