EM 1110-2-1100 (Change 1)
31 Jul 03
CHANNEL
(1) A natural or artificial waterway of perceptible extent which either periodically or continuously contains moving
water, or which forms a connecting link between two bodies of water. (2) The part of a body of water deep enough to be used
for navigation through an area otherwise too shallow for navigation. (3) A large strait, as the English Channel. (4) The
deepest part of a stream, bay, or strait through which the main volume or current of water flows (see THALWEG).
CHANNEL CAPACITY
The maximum flow which a channel is capable of transmitting without its banks being overtopped.
CHANNEL-MOUTH BAR
A bar built where a stream enters a body of standing water, resulting from decreased flow velocity.
CHARACTERISTIC WAVE HEIGHT
See SIGNIFICANT WAVE HEIGHT.
CHART
A special-purpose map, esp. one designed for navigation such as a bathymetric chart.
CHART DATUM
The plane or level to which soundings (or elevations) or tide heights are referenced (usually LOW WATER
DATUM). The surface is called a tidal datum when referred to a certain phase of tide. To provide a safety factor for
navigation, some level lower than MEAN SEA LEVEL is generally selected for hydrographic charts, such as MEAN LOW
WATER or MEAN LOWER LOW WATER. See DATUM PLANE.
CHEMICAL WEATHERING
Disintegration of rocks and sediments by chemical alteration of the constituent minerals or of the cementing matrix.
It is caused by exposure, oxidation, temperature changes, and biological processes.
CHENIER
A long, narrow wooded beach ridge or sandy hummock forming roughly parallel to a prograding shore, usually
seaward of marsh and mud-flat deposits (as along the south coast of Louisiana)
CHOP
The short-crested waves that may spring up quickly in a moderate breeze, and which break easily at the crest. Also
WIND CHOP.
CHOPPY SEA
Short, rough waves tumbling with a short and quick motion. Short-crested waves that may spring up quickly in a
moderate breeze, and break easily at the crest.
CLAPOTIS
The French equivalent for a type of STANDING WAVE. In American usage it is usually associated with the
standing wave phenomenon caused by the reflection of a nonbreaking wave train from a structure with a face that is vertical
or nearly vertical. Full clapotis is one with 100 percent reflection of the incident wave; partial clapotis is one with less than
100 percent reflection.
CLASTIC ROCKS
Rocks built up of fragments which have been produced by weathering and erosion of pre-existing rocks and
minerals and, typically, transported mechanically to their point of deposition.
CLAY
A fine grained, plastic, sediment with a typical grain size less than 0.004 mm. Possesses electromagnetic properties
which bind the grains together to give a bulk strength or cohesion. See SOIL CLASSIFICATION.
A-14
Appendix A Glossary of Coastal Terminology
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