SEISMIC SEA WAVE. See TSUNAMI. 



SEMIDIURNAL TIDE. A tide with two high and two low waters in a tidal day with 

 comparatively little diurnal inequality. (See Figure A-10.) 



SET OF CURRENT. The direction toward which a current flows. 



SETUP, WAVE. Superelevation of the water surface over normal surge elevation 

 due to onshore mass transport of the water by wave action alone. 



SETUP, WIND. See WIND SETUP. 



SHALLOW WATER. (1) Commonly, water of such a depth that surface waves are 

 noticeably affected by bottom topography. It is customary to consider 

 water of depths less than one-half the surface wavelength as shallow 

 water. See TRANSITIONAL ZONE and DEEP WATER. (2) More strictly, in 

 hydrodynamics with regard to progressive gravity waves, water in which the 

 depth is less than 1/25 the wavelength; also called VERY SHALLOW WATER. 



SHEET PILE. See PILE, SHEET. 



SHELF, CONTINENTAL. See CONTINENTAL SHELF. 



SHELF, INSULAR. See INSULAR SHELF. 



SHINGLE. (1) Loosely and commonly, any beach material coarser than ordinary 

 gravel, especially any having flat or flattish pebbles. (2) Strictly and 

 accurately, beach material of smooth, well-rounded pebbles that are 

 roughly the same size. The spaces between pebbles are not filled with 

 finer materials. Shingle often gives out a musical sound when stepped on. 



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 heoome shallow gradually. (2) To cause to become 

 shallow. (3) To proaeed 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. 



SHOALING FACTOR. See SHOALING 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). See Figure A-1. 



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