EM 1110-2-1100 (Change 1)
31 Jul 03
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
See SHOALING COEFFICIENT.
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). Also used in a general sense to mean the
coastal area (e.g., to live at the shore). Also sometimes known as the LITTORAL.
A line at right-angles to the contours in the surf zone.
A terrace made along a COAST by the action of waves and shore currents; it may become dry land by the uplifting
of the shore or the lowering of the water. Also known as shore platform or wave-cut platform.
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)
The intersection of a specified plane of water with the shore or beach (e.g., the high water shoreline would be the
intersection of the plane of mean high water with the shore or beach). The line delineating the shoreline on National Ocean
Service nautical charts and surveys approximates the mean high water line (United States).
The development of strategic, long-term and sustainable coastal defense and land-use policy within a sediment cell.
A wave, the crest length of which is of the same order of magnitude as the wave length. A system of short-crested
waves has the appearance of hills being separated by troughs.
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.
Experience indicates that a careful observer who attempts to establish the character of the higher waves will record values
which approximately 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 recurring of the larger well-defined waves in the record under
Appendix A Glossary of Coastal Terminology