EM 1110-2-1100 (Change 1)
31 Jul 03
ALONGSHORE
Parallel to and near the shoreline; LONGSHORE.
ALTIMETER
An instrument that determines its distance above a particular surface.
ALTIMETER, LASER
An instrument that determines altitude by measuring the length of time needed for a pulse of coherent light to travel
from the instrument to the surface and back, and multiplies half this time by the speed of light to get the straight-line distance
to the surface.
ALTIMETER, LIDAR
See ALTIMETER, LASER.
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 still-water level to wave crest. For a sinusoidal wave, the amplitude is one-half the wave height. (2)
The semirange of a constituent tide.
ANCHOR ICE
Spongy underwater ice formed on a submerged object or attached to the bottom of a shallow body of water which is
itself not frozen; syn. bottom ice
ANGLE OF REPOSE
The maximum slope (measured from the horizontal) at which soils and loose materials on the banks of canals, rivers
or embankments will stay stable.
ANISOTROPIC
Having properties that change with changing directions.
ANOXIC
Refers to an environment that contain little or no dissolved oxygen and hence little or no benthic marine life. These
conditions arise in some basins or fjords where physical circulation of seawater is limited.
ANTIDUNES
BED FORMS that occur in trains and are in phase with, and strongly interact with, gravity water-surface waves.
ANTINODE
See LOOP.
APRON
Layer of stone, concrete or other material to protect the toe of a structure.
AQUATIC MATERIAL PLACEMENT
Comprises all placement options under which the dredged material is submerged under water and remains
water-saturated after placement terminates.
AQUIFER
A geologic formation that is water-bearing, and which transmits water from one point in the formation to another.
ARCHIPELAGO
A sea that contains numerous islands; also the island group itself.
A-2
Appendix A Glossary of Coastal Terminology
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