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APPENDIX A 

 GLOSSARY O r TERMS 



ACCRETION - May be either NATURAL or ARTIFICIAL. Natural accretion is 

 the buildup of land, solely by the action of the forces of nature, 

 on a BEACH by deposition of waterbome or airborne material. 

 Artificial accretion is a similar buildup of land by reason of an 

 act of man, such as the accretion formed by a groin, breakwater, 

 or beach fill deposited by mechanical means. Also AGGRADATION. 



ADVANCE (OF A BEACH) - (1) A continuing seaward movement of the shore- 

 line. (2) A net seaward movement of the shoreline over a specified 

 time. Also PROGRESSION. 



AGE, WAVE - The ratio of wave velocity to wind velocity (in wave fore- 

 casting theory) . 



AGGRADATION - See ACCRETION. 



ALLUVIUM - Soil (sand, mud, or similar detrital material) deposited by 

 streams, or the deposits formed. 



ALONGSHORE - Parallel to and near the shoreline; same as LONGSHORE. 



AMPLITUDE, WAVE - (1) The magnitude of the displacement of a wave from a 

 mean value. An ocean wave has an amplitude equal to the vertical 

 distance from Stillwater level to wave crest. For a sinusoidal 

 wave, amplitude is one-half the wave height. (2) The semirange 

 of a constituent tide. 



ANTIDUNES - BED FORMS that occur in trains, and are in phase with and 

 strongly interact with gravity water-surface waves. 



ANTINODE - See LOOP. 



ARTIFICIAL NOURISHMENT - The process of replenishing a beach with material 

 (usually sand) obtained from another location. 



ATOLL - A ring-shaped coral reef, often carrying low sand islands, 

 enclosing a lagoon. 



ATTENUATION - (1) A lessening of the amplitude of a wave with distance 

 from the origin. (2) The decrease of water-particle motion with 

 increasing depth. Particle motion resulting from surface oscillatory 

 waves attenuates rapidly with depth, and practically disappears at 

 a depth equal to a surface wavelength. 



AWASH - Situated so that the top is intermittently washed by waves or 



tidal action. Condition of being exposed or just bare at any stage 

 of the tide between high water and chart datum. 



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