SHOAL (noun) - A detached elevation of the sea bottom^ comprised of any 



material except rock or coral, which may endanger surface navigation. 



SHOAL (verb) - (1) To become shallow gradually, (2) To cause to become 

 shallow. (3) To proceed from a greater to a lesser depth of water. 



SHOALING COEFFICIENT - The ratio of the height of a wave in water of any 

 depth to its height in deep water with the effects of refraction, 

 friction, and percolation eliminated. Sometimes SHOALING FACTOR 

 or DEPTH FACTOR. See also ENERGY COEFFICIENT and REFRACTION 

 COEFFICIENT. 



SHORE - The narrow strip of land in immediate contact with the sea, 



including the zone between high and low water lines. A shore of 

 unconsolidated material is usually called a beach. (See Figure 

 A-1.) 



SHOREFACE - The narrow zone seaward from the low tide SHORELINE covered 

 by water over which the beach sands and gravels actively oscillate 

 with changing wave conditions. See INSHORE (ZONE) and Figure A-1. 



SHORELINE - The intersection of a specified plane of water with the shore 

 or beach, (e.g., the highwater shoreline would be the intersection 

 of the plane of mean high water with the shore or beach.) The line 

 delineating the shoreline on U. S. Coast and Geodetic Survey nautical 

 charts and surveys approximates the mean high water line. 



SIGNIFICANT WAVE - A statistical term relating to the one-third highest 

 waves of a given wave group and defined by the average of their 

 heights and periods. The composition of the higher waves depends 

 upon the extent to which the lower waves are considered. Experi- 

 ence indicates that a careful observer who attempts to establish 

 the character of the higher waves will record values which approxi- 

 mately fit the definition of the significant wave. 



SIGNIFICANT WAVE HEIGHT - The average height of the one-third highest 

 waves of a given wave group. Note that the composition of the 

 highest waves depends upon the extent to which the lower waves are 

 considered. In wave record analysis, the average height of the 

 highest one-third of a selected number of waves, this number being 

 determined by dividing the time of record by the significant period. 

 Also CHARACTERISTIC WAVE HEIGHT. 



SIGNIFICANT WAVE PERIOD - An arbitrary period generally taken as the 



period of the one-third highest waves within a given group. Note 

 that the composition of the highest waves depends upon the extent 

 to which the lower waves are considered. In wave record analysis, 

 this is determined as the average period of the most frequently re- 

 curring of the larger well-defined waves in the record under study. 



SILT - See SOIL CLASSIFICATION. 



A-33 



