EM 1110-2-1100 (Change 1)
31 Jul 03
E
EAGER
See BORE.
EBB
Period when tide level is falling; often taken to mean the ebb current which occurs during this period.
EBB CURRENT
The movement of a tidal current away from shore or down a tidal stream. In the semidiurnal type of reversing
current, the terms greater ebb and lesser ebb are applied respectively to the ebb currents of greater and lesser velocity of each
day. The terms of maximum ebb and minimum ebb are applied to the maximum and minimum velocities of a continuously
running ebb current, the velocity alternately increasing and decreasing without coming to a slack or reversing. The
expression maximum ebb is also applicable to any ebb current at the time of greatest velocity.
EBB INTERVAL
The interval between the transit of the moon over the meridian of a place and the time of the following strength of
ebb.
EBB SHIELD
High, landward margin of a flood-tidal shoal that helps divert ebb-tide currents around the shoal.
EBB STRENGTH
The EBB CURRENT at the time of maximum velocity.
EBB TIDAL DELTA
The bulge of sand formed at the seaward mouth of TIDAL INLETS as a result of interaction between tidal currents
and waves. Also called inlet-associated bars and estuary entrance shoals.
EBB TIDE
The period of tide between high water and the succeeding low water; a falling tide. (See Figure II-5-16.)
ECHO SOUNDER
An electronic instrument used to determine the depth of water by measuring the time interval between the emission
of a sonic or ultrasonic signal and the return of its echo from the bottom.
ECOSYSTEM
The living organisms and the nonliving environment interacting in a given area, encompassing the relationships
between biological, geochemical, and geophysical systems.
EDDY
A circular movement of water formed on the side of a main current. Eddies may be created at points where the
main stream passes projecting obstructions or where two adjacent currents flow counter to each other.
EDDY CURRENT
See EDDY.
EDGE WAVE
An ocean wave parallel to a coast, with crests normal to the shoreline. An edge wave may be STANDING or
PROGRESSIVE. Its height diminishes rapidly seaward and is negligible at a distance of one wavelength offshore.
EKMAN TRANSPORT
Resultant flow at right angles to and to the right of the wind direction (in the northern hemisphere) referred to as
UPWELLING and DOWNWELLING.
Appendix A Glossary of Coastal Terminology
A-27
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