glossary of coastal engineering terms

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U. S. ARMY, COPFS OF ENG@NEIFRS
COASTAL ENGNEEMNG
RESEARCH CIENTER

GB Approved for pubfic Mbsuzz d@Oriboicn UnHuMftd.
450.6
G511
1972

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nated by other authorized documents.

Glossary of Coastal Engineering Terms

Compiled by
Richard H. Allen

MISCELLANEOUS PAPER 2-72
APRIL 1972

U S DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CENTER
2234 SOUTH HOBSON AVENUE
CHARLESTON , SC 29405-24 13

U. S. ARMY, CORPS OF ENGINEERS
COASTAL ENGINEERING
RESEARCH CENTER

Approved for public release@'distri
bution unlimited.

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ABSTRACT

A glossary of terms used by coastal engineers is presented. The
terms apply to such subjects as waves, tides, littoral processes, shore
protection, shore structures', and coastal geomorphology. Primary sources
are cited.

FOREWORD

Shore Protection, Planning and Design, Technical Report No. 4 (TR-4)
and its glossary were revised in 1961 (2d edition) and 1966 (3d edition).
In preparing the glossary for the first edition of TR-4, a glossary pre-
pared at the University of California by Robert L. Wiegel was of special
value., Weigel's glossary was published in July 1953 by the Council on
Wave Research, the Engineer Foundation, as Waves, Tides, Currents, and
Beaches: Glossary of Terms and List of Standard Symbols.

With increased interest in coastal engineering, new terms are being
developed @tnd progress toward a more complete and accepted understanding of
existing terms is being made. The purpose of this Miscellaneous Paper is
to present the latest definitions of terms used in the coastal engineering
field. The primary sources used in the compilation of this glossary were:

American Geological Institute (1957) Glossary of Geology and Related
Sciences with Supplement. 2d Edition.
American Meteorological Society (19S9) - Glossary of Meteorology.
U.S. Army Coastal Engineering Research Center (1966) - Shore Protection,
Planning and Design, Technical Report No. 4. 3d Edition.
U.S. Coast and Geodetic Survey (1949) - Tide and Current Glossary, Special
Publication No. 228. Revised (1949) Edition.
U..S. Navy Oceanographic Office (1966) - Glossary of Oceanographic Terms.,
Special Publication (SP-3S). 2d Edition.
The glossary was compiled by Richard H. Allen, Chief, Publications
Branch under the general supervision of George M. Watts, Chief, Engineering
Development Division.

The glossary was reviewed by members of the Coastal Engineering
Research Board, the Office of the Chief of Engineers, and the U.S. Army
Waterways Experiment Station. CERC is grateful for the valuable sug-
gestions provided by these,re..viewers.
At the time of publication,Lieutenant, C.olonel-Don S. McCoy was
Director of CERC; Thorfidike-Savi'lle, Jr. wastTechnical Director.

NOTE: Comments on this glossary are invited. Readers.who find omissions
or errors are encouraged to submit their suggestions.
This report is published-under authority,of.Public Law, 79th Congress
approved 31 July 1945, as supplemented by Public Law 172, 88th Congress,
approved 7 November 1963.

V.0 aa W!20q,*%%

A GLOSSARY OF

COASTAL ENGINEERING 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 waterborne 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 thevertical
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 distanc e
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.

BACKBEACH See BACKSHORE.

BACKRUSH The seaward return of the water following the uprush of the
waves. For any given tide stage the point of farthest return sea-
ward of the backrush is known as the LIMIT of.BACKRUSH or LIMIT
BACKWASH. (See Figure A-2.)

BACKSHORE - That zone of the shore or beach lying between the foreshore.
and the coastline and acted upon by waves only during severe storms,
especially when combined with exceptionally high water. Also
BACKBEACH. It comprises the BERM or BERMS. (See Figure A-1.)

BACKWASH - (1) See BACKRUSH. (2) Water or waves thrown back by an
obstruction suchas a ship, breakwater, or cliff.

BANK (1) The rising ground bordering a lake, river, or sea; of a
river or channel, designated as right or left as it would appear
facing downstream. (2) An elevation of the sea floor of large
area, located on a Continental (or island) Shelf and over which
the depth is relatively shallow but sufficient for safe surface
navigation; a group of shoals. (3) In its secondary sense, a
shallow area consisting of shifting forms of silt, sand, mud, and
gravel, but in this case it is only used with a qualifying word
such. as "sandbank" or "gravelbank".

BAR A submerged or emerged embankment of sand, gravel, or other un-
consolidated material built on the sea floor in shallow water by
waves and currents.. See BAYMOUTH BAR, CUSPATE BAR. (See Figures
A-2 and A-9.)

BARRIER BEACH - A bar essentially parallel to the shore, the crest of
which is above norinal'high water level. Also called OFFSHORE
BARRIER and BARRIER ISLAND. (See Figure A-9.)

BARRIER LAGOON - A bay roughly parallel to the coast and separated from
the open ocean by barrier islands. Also the body of water encircled
by coral islands and reefs, in which case it may be called an atoll
lagoon.

BARRIER REEF - A coral reef parallel to and separated from the coast by
a lagoon that is too deep for coral growth. Generally, barrier
reefs follow the coasts for long-distances,and are cut through at
irregular intervals by channels or passes.

BASIN, BOAT - A naturally or arti,ficially:enclosed or nearly,enclosed
harbor area for small craft.'

BATHYMETRY The measurIeIment of depths of water in:o*ceans, seas, and
lakes; als6-information' derived from such measurements.

BAY - A recess in the shore or an inlet of a sea between two capes or
headlands,, not as large as a gulf but larger than a cove. See
also BIGHT, EMBA@MENT. (See Figure A-9.)

BAYMOUTH BAR - A bar extending partly or entirely across the mouth of
a bay. (See Figure A-9.)
BAYOU - A minor sluggish waterway Or estuarial creek, tributary to, or
connecting, other streams or bodies of water. Its course is usually
through lowlands or swamps. Sometimes called SLOUGH.

BEACH - The zone of unconsolidated material that extends landward from
the low water line to the place where there is marked change in
material or physiographic form, or to the line of permanent vege-
tation (usually the effective limit of storm waves). The seaward
limit of a beach - unless otherwise specified - is-the mean low
water line. A beach includes FORESHORE and BACKSHORE. (See
Figure A-1.)

BEACH ACCRETION - See ACCRETION.

BEACH BERM - A nearly horizontal part of the beach or backshore formed
by the deposit of material by wave action. Some beaches have no
berms, others have one or several. (See Figure A-1.)

BEACH CUSP - See CUSP.

BEACH EROSION The carrying away of beach materials by wave action,
tidal currents, littoral currents, or wind.

BEACH FACE - The section of the beach normally exposed to the action of
the wave uprush. The FORESHORE of a BEACH. (Not synonymous with
SHOREFACE.) (See.Figure A-2.)

BEACH RIDGE See RIDGE, BEACH.

BEACH SCARP See SCARP, BEACH.

BEACH WIDTH The horizontal dimension of the beach measured normal to
the shoreline.

BED FORMS - Any deviation from a flat bed that is readily detectable by
eye, and higher than the largest sediment size present in the parent
bed material; generated on the bed of an al luvial channel by the
flow.

BEDLOAD See LOAD.

BENCH - (1) A level or gently sloping erosion plane inclined seaward.
(2) A nearly horizontal area at about the level of maximum high
water on the sea side of a dike.

BENCH MARK - A permanently fixed point of known elevation. A primary
bench mark is one close to a tide station to which the tide staff
and tidal datum originally are referenced.

BERM, BEACH See BEACH BERM.

BERM CREST The seaward limit of a berm. Also BERM EDGE. (See
Figure A-1.)

BIGHT- A bend in a coastline forming an open bay. A bay formed by
such a bend. (See Figure A-8.)

BLOWN SANDS See EOLIAN SANDS.

BLUFF - A hi gh steep bank or cliff.

BOLD COASTz- A prominent land mass that rises steeply from the sea..

BORE - A very rapid rise of the tide in which the advancing water pre-
sents an abrupt front of considerable height. In shallow estuaries
where the range of tide is large, the high water is propagated in-
@ward faster than the low water because of the greater depth at high
water.' If the high water overtakes the low water, an abrupt front
is presented with the high water crest finally falling forward as
the tide continues to advance. Also EAGER.

BOTTOM - The ground or bed under any body of water; the bottom of the
sea. (See Figure A-1.)

BOTTOM (NATURE OF) The composition or character of the bed of an ocean
or other body of water (e.g-, clay, coral, gravel,.mud, ooze,
pebbles, rock, shell, shingle, hard, or soft).

BOULDER - A rounded rock more than 10 inches in diameter; larger than a
cobblestone. See SOIL CLASSIFICATION.

BREAKER - A wave breaking on a shore, over-a-reef, etc. Breakers may be
classified into four types (see Figure A-4):

SpMing bubbles and turbulent water spill down front face of
wave. - The upper-25 percent of the front face may become
vertical before breaking. Breaking generally across over
quite a distance.

PZunging - crest curls over air pocket; breaking is usually with
a crash. Smooth splash-up usually follows.

CoUapsing - breaking occurs over lower half of wave. Minimal
air pocket and usually no splash-up. Bubbles and foam
present. (See Figure A-12.)

Surging - wave peaks up, but bottom rushes forward from under
wave, and wave slides up beach face with little or no
bubble production. Water surface remains almost plane
except where ripples may be produced on the beachface
during runback.

BREAKER DEPTH - The stillwater depth at the point where a wave breaks.
Also BREAKING DEPTH. (See Figure A-2.)

BREAKWATER - A structure protecting a shore area, harbor, anchorage,
or basin from waves.

BULKHEAD - A structure or partition to retain or prevent sliding of the
land. A secondary purpose is to protect the upland againstdamage
from wave action.

BUOY-7 A float; especially a floating object moored to the bottom, 'to
mark a channel, anchor, shoal, rock, etc.

BUOYANCY - The resultant of upw'ard forces, exerted by the water-on
a submerged or floating body, equal to the weight of the water
displaced by this body.

BYPASSING, SAND - Hydraulic or mechanical movement of sand from the
accreting updrift side to the eroding downdrift side of'an',inlet
or harbor entrance. The hydraulic movement may include natural
as well as movement caused by man.

CANAL - An artificial watercourse cut through a land area for such,uses
as navigation and irrigation.

CANYON - A relatively narrow, deep depression with steep slopes, the
bottom of which grades continuously downward. May be underwater
(submarine) or on land (subaerial).

CAPE - A relatively extensive land area jutting seaward from a continent
or large island which prominently marks a change in, or interrupts
notably, the coastal trend; a prominent feature. (See Figure A-8.)

CAPILLARY WAVE - A wave whose velocity or propagation is controlled
primarily by the surface tension of the liquid in which the wave is
traveling. Water waves of length less than about I inch are con-
sidered capillary waves. Waves longer than I inch and shorter than
2 inches are in an indeterminate zone between CAPILLARY and GRAVITY
WAVES. See RIPPLE.

CAUSEWAY A raised road, across wet or'marshy ground, or across water.

CAUSTIC In refraction.of waves, the'name given to the curve to which
adjacent orthogonals of waves refracted by a.bottom whose contour
lines are. curved, are tangents. The occurrence of a caustic always
marks a region of crossed orthogonals and high wave convergence.

CAY - See KEY.

CELERITY Wave speed.

CENTRAL PRESSURE INDEX (C PI) - The estimated minimum barometric pressure
in the eye (approximate center) of a particular hurricane. The CPI
is considered the most stable index to intensity of hurricane wind
velocities in the periphery of the storm; the highest wind speeds
are associated with storms having the lowest CPI.

CHANNEL A natural or artificial waterway of perceptible extent
which either periodically or continuously contains moving water,
or which form 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.

CHARACTERISTIC WAVE HEIGHT See SIGNIFICANT WAVE HEIGHT.

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 DATL94 PLANE.

CHOP - The short-crested waves that may spring up quickly in a moderate
breeze, and break easily at the crest. Also WIND CHOP.

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 Aace 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.

CLAY See SOIL CLASSIFICATION.

CLIFF A high, steep face of rock; a precipice. See also SEA CLIFF.

CNOIDAL WAVE - A type of wave in shallow water (depth of water is less
than 1/8 to 1/10 the wavelength). 7- surface profile is expressed
in terms of the Jacobian eliptic function cn u; hence the term
enoidal.

COAST - A strip of land of indefinite width (may be several miles) that
extends from the shoreline inland to the first major change in
terrain features. (See Figure A-1.)

COASTAL AREA - The land and sea area bordering the shoreline. (See
Figure A@1.)

COASTAL PLAIN - The plain composed of horizontal or gently sloping
strata of elastic materials fronting the coast, and generally
representing a strip of sea bottom that has emerged from the
sea in recent geologic time.

COASTLINE - (1) Technically, the line that forms the boundary between
the COAST and the SHORE. (2) Commonly, the line that forms the
boundary between the land and the water.

COBBLE (COBBLESTONE) - See SOIL CLASSIFICATION.

COMBER - (1) A deepwater wave whose crest is pushed forward by a strong
wind; much larger than a whitecap. (2) A long-period.breaker.

CONTINENTAL SHELF - The zone bordering a continent and extending from
the low water line to the depth (usually about.100 fathoms) Where
there is a marked or rather steep descent,toward a greater depth.

CONTOUR - A line on a map or chart representing points of equal eleva-
tion with relation to a DATUM. It is called an ISOBATH when con-
nectin g points of equal depth below a datum.

CONTROLLING DEPTH - The least depth in the navigable parts of a water-
way, governing the maximum draft of vessels that can enter.

CONVERGENCE - (1) In refraction phenomena, the decreasing of the dis-
tance between orthogonals in the direction of wave travel. Denotes
an area of increasing wave height and energy concentration. .(2) In
wind-setup P@enomena, the increase in setup observed over that which
would, occur in an equivalent rectangular basin of uniform depth,
caused by changes in planform or depth; also the decrease in basin
width or depth. causing such increase in setup.

CORAL - (1) (Biology) Marine coelenterates (Madreporaria), solitary or-
col'on'ial, which form a hard external covering of calcium compounds,
or other.materials. The corals which form large reefs are limited
to warm, shallow waters, while those forming solitary, minute
growths may be found in colder waters to great depths. (2) (Geology)
The concretion of coral polyps, composed almost wholly of calcium
carbonate, forming reefs, and tree-like and globular masses. May
also include calcareous algae and other organisms producing cal-'
careous secretions., such as bryozoans and hydrozoans.

CORE - A vertical cylindrical sample of the bottom sediments from which
the nature and stratification of the bottom may be determined.

COVE - A small, sheltered recess in a coast, often inside a larger
embayment. (See Figure A-8.)

CREST LENGTH, WAVE - The length of a wave aZong its crest. Sometimes
called CREST WIDTH.

CREST OF BERM - The seaward limit of a berm. Also BERM EDGE. (See
Figure A-1.)

CREST OF WAVE (1) The highest part of a wave. (2) That part of the
wave above stillwater level. (See Figure A-3.)

CREST wim, WAVE - See CREST LENGTH, WAVE.

CURRENT - A flow of water.

CURRENT, COASTAL One of the offshore currents flowing generally parallel
to the,shoreline in the deeper water beyond and near the surf zone.
They are not related genetically to waves and resulting surf, but
may be related to tides, winds, or distribution of mass.

CURRENT;DRIFT A broad, shallow, slow-moving ocean or lake current.
Opposite of CURRENT, STREAM.

CURRENT, EBB - The tidal current away from shore or down a tidal stream.
: Usually associated with the decrease in the height.of the tide.

CURRENT, EDDY See EDDY.

CURRENTS, FEEDER - The parts of the NEARSHORE CURRENT SYSTEM that flow
parallel to shore before converging and forming the neck of the
RIP CURRENT.

CURRENT, FLOOD - The tidal current toward shore or up a tidal stream.
Usually associated with the increase in the height of the tide.

CURRENT, INSHORE- See INSHORE,CURRENT.

CURRENT, LITTORAL - Any current in the littoral zone caused primarily by
wave,action, e.g., longshore current, rip current. See also CURRENT,
NEARSHORE.

CURRENT, LONGSHORE The littoral current in the breaker zone moving
essentially parallel to the shore, usually generated by waves
breaking at an angle to the shoreline.

CURRENT, NEARSHORE A current in the NEARSHORE ZONE. See Figure A-1.

CURRENT, OFFSHORE See OFFSHORE CURRENT.

CURR ENT, PERIODIC See CURRENT, TIDAL.

CURRENT, PERMANENT See PERMANENT CURRENT.

CURRENT, RIP - See RIP CURRENT.

CURRENT, STREAM - A narrow, deep, and swift ocean current, as the Gulf
Stream. Opposite of CURRENT, DRIFT.

CURRENT SYSTEM, NEARSHORE - See NEARSHORE CURRENT SYSTEM.

CURRENT, TIDAL - The alternating horizontal movement of water associated
with the rise and fall of the tide caused by the astronomical tide-
producing forc:es. Also CURRENT, PERIODIC. See also CURRENT, FLOOD
and CURRENT, EBB.

CUSP - One of a series of low mounds of beach material separated by
crescent-shaped troughs spaced at more or less regular intervals
along the beach face. Also BEACH CUSP. (See Figure A-7.)

CUSPATE BAR A crescent-shaped bar uniting with the shore at each end.
It may be formed by a single spit growing from shore and then turn-
ing back to again meet the shore, or by two spits gr owing from-the
shore and uniting to form a'bar of sharply cuspate form. (See
Figure A-9.)

CYCLOIDAL WAVE - A steep symmetrical wave whose crest forms an@Angle of
120 degrees. The wave form is that.of a cycloid. A trochoidal wave
of maximum steepness. See also TROCHOI DAL WAVE.

DAILY RETARDATION (OF TIDES) - The amount of time by which-corresponding
tidal phases.grow later day by day (about 50 minutes).

DATUM, CHART See CHART DATUM.

DATUM, PLANE- The horizontal plane to which soundings, ground elevations,
or water surface elevations are referred. Also REFERENCE PLANE..
The plane is called a TIDAL DATUM when defined by a certain phase
of the tide. The following datums are ordinarily used on hydro-
graphi c - charts:

MEAN LOW WATER - Atlantic coast (U. S.), Argentina, Sweden,
and Norway;
MEAN LOWER LOW WATER - Pacific coast (U. S.);
MEAN LOW WATER SPRINGS - United Kingdom, Germany, Italy, Brazil,
and Chile;
LOW WATER DATUM - Great Lakes (U. S. and Canada)@
LOWEST LOW WATER SPRINGS - Portugal;
LOW WATER INDIAN SPRINGS - India and Japan (See INDIAN TIDE
PLANE);
LOWEST LOW WATER - France, Spain, and.Greece.
A common datum used on topographic maps is based on MEAN SEA LEVEL.
See also BENCH MARK.

DEBRIS LINE - A line near the limit of storm wave uprush marking the
landward limit of debris deposits.

DECAY DISTANCE - The distance waves travel after leaving the generating
area (FETCH).

DECAY OF WAVES - The change waves undergo after they leave a generating
area (FETCH) and pass through a @-,4alm, or region of lighter winds.
In the process of decay, the significant wave height decreases and
the significant wavelength increases.

DEEP WATER - Water so deep that surface waves are little affectedby the
ocean bottom. Generally, water deeper than one-half the surface
wavelength is considered deep water.

DEFLATION - The removal of loose material from a beach or other land
surface by wind action.

DELTA - An alluvial deposit, roughly triangular or digitate in shape,
formed at a river mouth.

DEPTH -,The vertical distance from a specified tidal datum to the sea
floor.

DEPTH OF BREAKING - The stillwater depth at the point where the wave
breaks., Also,BREAKER DEPTH (See Figure A-2.)

DEPTH CONTOUR See CONTOUR.

DEPTH, CONTROLLING - See CONTROLLING DEPTH.

DEPTH FACTOR - See SHOALING COEFFICIENT.

DERRICK STONE See STONE, DERRICK.

DESIGN HURRICANE.@,See HYPOTHETTCAL,HURRICANE.

DIFFRACTION (of waer.waves) - The phenomenon by which energy is trans-
mitted laterally along a wave crest'. When a part of, a.t-rain,of,waves
is interrupted by a barrier, such as a breakwater, the effect of
diffraction is.manifested by propagation of waves into thesheltered
region within the barrier's geometric shadow.

DIKE(DYKE) A.wall or mound.built.around a 1OW71ying area- to prevent
'',flooding.

DIURNAL - Having a period or cycle of approximately one TIDAL DAY.
DIURNAL'TIDE ktide with on .ehigh water and one low water in a tidal
day. (See Figure A-10,.)

DIVERGENCE - (1) In refraction phenomena, the increasing of distance
between orthogonals in the direction of wave travel. Denotes an
area of decreasing wave height and energy concentration. (2) In
wind--setup phenomena, the decrease in setup observed unde:r that
Which would occur in an equivalent rectangular basin of-un*iform
depth, caused by changes.in planform or depth. Also the increase
in basin width or depth causing such decrease in setup.

DOLPHIN- A c 'luster of piles.

DOWNCOAST - In United States usage, the coastal direction generally
trending toward the south.

DOWNDRIFT - The direction of predominant movement of littoral materials.

DRIFT (noun) (1) Sometimes used as a short form for LITTORAL DRIFT
(2) The speed at which a current runs. (3) Also floating material
deposited on a beach (driftwood). (4) A deposit of a continental
ice sheet, as a drumlin.

DRIFT CURRENT - A broad, shallow, slow-mo.ving ocean or lake current.

DUNES - (1) Ridges or mounds of loose, wind-blown material, usually
sand. (See4igure A-7.) (2) BED FORMS smaller than bars but
larger than ripples that are out of phase with any water-surface
gravity waves associated with them.

DURATION - In wave forecasting, the length of time the wind blows in
nearly the same direction over the FETCH (generating area).

DURATION, MI141MUM The time necessary for steady-state wave conditions
to develop for a given wind velocity over a given fetch length.

EAGER See BORE.

EBB CURRENT The tidal current away from shore or upa tidal stream;
usually associated with the decrease in the height of the tide.
EBB tID*E - The period of tide between high water and the succeeding-low
water; a falling tide. (See Figure A-10.)

ECHO SOUNDER - An electronic instrument used to deter mine the depth of
water by measuring the time interval between emission of a sonic or
'ultrasonic signal and the return of its echo from the bottom.

EDDY - A circular-movement of water formed on the side of a main current.
Eddi6s@ may be created at points where the main stream passes pro-
jecting 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.

EMBANKMENT - An ar tificial bank such as a mound or dike, generally built
to hold back water or to carry a roadway.

EMBAYEP Formedinto a bay or bays, as an embayed shore.'

EMBAYMENT - An indentation in the shoreline forming an open bay.

ENERGY COEFFICIENT - The ratio of the energy in a wave per unit crest
length transmitted forward with the wave at a point in shallow water
to the energy in a wave per unit crest length transmitted forward
with the wave in deep water. On refraction diagrams this is equal
to the ratio of the distance between a pair of orthogonals at a
selected point to the distance between the same pair of orthogonals
in deep water. Also the square of the REFRACTION COEFFICIENT.

ENTRANCE The avenue of access or opening to a navigable channel.

EOLIAN SANDS.- (or BLOWN SANDS) - Sediments of sand size or smaller which
have been transported by winds. They may be recognized in marine
deposits off desert coasts by the greater angularity of the grains
compared with waterborne particles.

EROSION - The wearing away of land by the action of natural forces. On
a beach, the carrying away of beach material by wave action, tidal
currents, littoral currents, or by deflation.

ESCARPMENT - A more or less continuous line of cliffs or steep slopes
facing in one general direction which are caused by erosion or
faulting. Also SCARP. (See Figure A-1.)

ESTUARY (1) The part of a river that is affected by tides. (2) The
region near a river mouth in which the fresh water of the river
mixes with the salt water of the sea.

EYE In meteorology, usually the "eye of the storm" (hurricane); the
roughly circular area of comparatively light winds and fair weather
found at the center of a severe tropical cyclone.

FAIRWAY - The parts of a waterway that are open and unobstructed for
navigation. The main traveled part of a waterway; a marine
thoroughfare.

FATHOM - A unit of measurement used for soundings. It is equal to 6 feet
(1.83 meters).

FATHOME TER- The copyrighted trademark for a type of echo sounder.

FEEDER BEACH - An artificially widened.beach serving to nourish downdrift
beaches by natural littoral currents or forces.

FEEDER CURRENT - See CURRENT, FEEDER.

FEELING BOTTOM - The action of a deepwater wave on runnin g into shoal
water and beginning to be'influenced by the bottom.

FETCH - The area in which SEAS are generated by a wind having a rather
constant direction and speed. Sometimes used synonymously with
FETCH LENGTH. Also GENERATING AREA.

FETCH LENGTH - The horizontal distance (in the direction -of the wind)
over which a wind generates SEAS or creates a WIND SETUP.. -

FIRTH - A narrow arm of the sea; also the opening of a river into the
sea.

FIORD (FJORD) - A narrow, deep, steep-walled inlet of the sea, usually
formed by entrance of the sea into a deep glacial trough.

FLOOD CURRENT - The tidal current toward shore or up a tidal stream,
usually associated with the increase in the height of the tide.

FLOOD TIDE - The period of tide between low water and the succeeding
high water; 4 rising tide. (See Figure A-10.)

FOAM LINE - The front of a wave as it advances.shoreward, afterit has
broken. (See Figure A-4.)

FOLLOWING WIND - Generally, same as tailwind; in wave forecasting, wind
blowing in the direction of ocean-wave advance..

FOREDUNE- The front dune immediately behind,the backshore..

FORERUNNER - Low, long-period ocean SWELL which commonly precedes the
main swell from a distant storm, especially atropical. cyclone.

FORESHORE - The part of the shore lying between the crest of the seaward
berm (or upper limit of wave wash at high tide) and the ordinary low
water mark, that is ordinarily traversed by the uprush and backrush
of the waves as the tides rise and fall. See BEACH FACE. (See
Figure A-1.)

FORWARD SPEED (HURRICANE) - Rate of.movement (propagation) of the hurri-
cane eye in uph or knots.

FREEBOARD - The additional height-of a structure above design high water
level to prevent overflow. Also, at a given time, the vertical dis-
tance between the water level and the top of the structure. On a
ship, the distance from the water line to main deck or gunwale.

FRINGING REEF - A coral reef attached directly to an insular or conti-
nental shore.

FRONT OF THE FETCH In wave forecasting, the end ofthe generating area
toward which.the wind is blowing.

FROUDE NUMBER - The dimensionless ratio of the inertial force to the
force of gravity for a given fluid flow. It may be given as
Fr = V2/Lg where V is a tharacteristic velocity, L is a charac-
teristic length, and g the acceleratior of gravity; or as the
square root of this number.

GENERATING AREA - In wave forecasting the continuous area of water
surface over which the wind blows in nearly a constant direction.
Sometimes used synonymously with FETCH LENGTH. Also FETCH.

GENERATION OF WAVES - (1) The creation of waves by natural or mechanical
means. (2) The creation and growth of waves caused by a wind blowing
over a water surface for a certain period of time. The area involved
is called the GENERATING AREA or FETCH.

GEOMETRIC MEAN DIAMETER - The diameter equivalent of the arithmetic mean
of the logarithmic frequency distribution. In the analysis of beach
sands, it is taken as that grain diameter determined graphically by.
the intersection of a straight line through selected boundary sizes,
(generally points on the distribution curve where 16 and 84 percent
of the sample is coarserby weight) and a vertical line through the
median diameter of the sample.

- In wave diffraction theory, the area outlined by
GEOMETRIC SHADOW
drawing straight lines paralleling the direction of wave approach
through the extremities of the protective structure. It differs
from the actual protected area to the extent that the diffraction
and refraction effects modify the wave pattern.

GEOMORPHOLOGY - That branch of both physiography and geology which deals
with the form of the earth, the general configuration of its surface,
and the changes that take place in the evolution of land forms.

GRADIENT (GRADE) - See SLOPE. With reference to winds or.currents, the
rate of increase or decrease in speed, usually in the vertical; or
the curve that represents this rate.

GRAVEL - See SOIL CLASSIFICATION.

GRAVITY WAVE - A wave whose velocity of'propagation is controlled pri-
marily by gravity. Water waves more than 2 inches long are con-
sidered gravity waves. Waves longer than 1 inch and shorter than
2 inches are in an indeterminate zone between CAPILLARY and GRAVITY
WAVES. See RIPPLE.

GROIN (British, GROYNE) - A shore protection structure built (usually
perpendicular to the shoreline) to trap littoral*drift or:retard
erosion of the shore.

GROIN SYSTEM - A series of groins acting together to protect a section
of beach. Commonly called a groin field.

GROUND SWELL - A long high ocean swell; also, this swell as it rises to
prominent,height in shallow water.,.

GROUND WATER - Subsurface water occupying the zone of saturation., In a
strict,sense, the term is applied only to water below the WATER
TABLE.

GROUP VELOCITY - The velocity of a wave group. In deep water, it is
equal to one-half,the velocity of the individual [email protected]
group.

GULF - A large embayment in a,coast; the entrance is gen erally:wider than
the length. I... I '@ t@@.

GUT - (1) A nar row passage such as a strait or inlet. (2) A channel in
otherwise shallower water, generally formed by water in motion.

HALF-TIDE LEVEL - MEAN TIDE LEVEL.

HARBOR (British, HARBOUR) Any protected water area affording a place
of safety for vessels. See also PORT.

HARBOR OSCILLATION (Harbor Surging) - The nontidal vertical water move-
ment in a harbor or bay. Usually the vertical motions are low, but
when oscillations are-excited by a tsunami or storm surge, they may
be quite large. Variable winds, air oscillations, or surf beat also
may cause oscillations. See SEICHE.

HEADLAND (HEAD) - A high steep-faced promontory extending into the sea.

HEAD OF RIP - The part of a rip current that has widened out seaward of
the breakers. See also CURRENT, RIP; CURRENT, FEEDER; and NECK (RIP).

HEIGHT OF WAVE - See WAVE HEIGHT.

HIGH TIDE, HIGH WATER (HW) - 7he,maximum elevation reached by each rising
tide. See TIDE. (See Figure A-40.)

HIGH WATER@OF ORDINARY SPRING TIDES (HWOST) - A tidal datum appearing in
some British publications, based on high water of ordinary spring
tides.

HIGHER HIGH WATER (HHW) - The higher of the two high waters of any tidal
day. The single high water occurring daily during periods when
the tide is diurnal is considered to be a higher high water.
(See Figure A-10.)

HIGHER.LOW WATER (HLW) - The higher of two low waters of any tidal day.*
(See Figure A-10.)

HIGH WATER - See HIGH TIDE.
HIGH WATER LINE - In strictness,'the intersection of the plane o f mean
high water with the shore. The shoreline delineated on the nautical
charts of the U. S. Coast and Geodetic Survey is an approximation of
the high water line. For specific occurrences, the highest eleva-
tion on the shore reached during a storm or rising tide, including
meteorological effects.

HINDCASTING, WAVE - The use of historic synoptic wind charts to calculate
wave characteristics that probably occurred at some past time.

'HOOK -w A spit or narrow cape of sand or gravel which turns landward at
the outer end.

HURRICANE - An intense tropical cyclone in which winds tend to spiral
inward toward a core of low pressure, with maximum surface wind
velocities that equal or exceed 75 mph (65 knots) for several
minutes or longer at some points. TROPICAL STORM is the term
applied if maximum winds are less than 75 mph.

HURRICANE PATH OR TRACK - Line of movement (propagation) 6f the eye
through an area.

HURRICANE STAGE HYDROGRAPH - A.continuous graph representing water level
.stages that would be recorded in a gage well located at a specified
point of interest during the passage of a particular hurricane, as-
suming that effects of relatively short-period waves are eliminated
from the record by damping features'of the gage well. Unless
specifically excluded and separately accounted for, hurricane surge
hydrographs are assumed to include effects of astronomical tides,
.barometric pressure differences, and all other factors that in-
fluence water level stages within a properly designed gage well
located at a specified point.

HURRICANE SURGE HYDROGRAPH - A continuous graph represen ting the differ-
ence between the hurricane stage hydrograph and the water stage
hydrograph that would have prevailed at the same point and time
if the hurricane had not occurred.

HURRICANE.WIND PATTERN or ISOVEL PATTERNS - An actual or graphical repre-
sentation of near-surface wind velocities covering the entire area
of a hurricane at a particular instant. Isovels are,lines connecting
points of simultaneous equal wind velocities, usually referenced 30
feet above the surface, in knots or mph; wind directions at various
points are indicated by arrows or deflection angles on the isovel
charts. Isovel charts are usually prepared at each hour during a
hurricane, but for each half hour during critical periods.

HYDRAULICALLY EQUIVALENT GRAINS - Sedimentary particles that settle at
the-same rate under the same conditions.

HYDROGRAPHY - (1) A configuration of an underwater surface including its
relief, bottom materials, coastal structures, etc. (2) The de-
scription and study of seas, lakes, rivers, and other waters.

HYPOTHETICAL HURRICANE (11HYPO-HURRICANE11) - A representation of a hurri-
cane, with specified characteristics, that is assumed to occur in
a particular study area, following a specified path and timing
sequence.

TRANSPOSED A hypo-hurricane based on the storm transposition
principle is assumed to have wind patterns and.other charac-
teristics basically comparable to a specified hurricane of
re*cord, but istransposed to follow.a new path to serve as a
basis for computing a hurricane surgehydrograph that would
be expected at a selected point. Moderate adjustments in
timing or rate of forward movement may be made also, if these
are compatible with meteorological considerations and study
objectives.
HYPO-HURRICANE BASED-ON GENERALIZED PARAMETERS - Hypo-hurricane
estimates based on various logical.combinations of hurricane
characteristics used in estimating hurricane surge magnitudes
corresponding to a range of probabilities and potentialities.
The Standard Project Hurricane (SPH) is most commonly used
for this purpose, but estimates corresponding to more severe
or less severe assumptions are important in some project
investigations. :I

STANDARD PROJECT HURRICANE (SPH) - A hypothetical hurricane in-
tended to represent the most severe combination of hurricane
parameters that is reasonabLy,characteristic of a specified
region, excluding extremely rare combinations. It is further
assumed that the SPH would approach,a given project site from
such direction, and at.such rate of movement as to produce
the highest hurricane surge hydrograph, considering pertinent
hydraulic characteristics of the.area. Based on this concept,
and extensive meteorological studies and probability analyses,
atabulation'of "Standard Project Hurricane Index Character-
istics" mutually,agreed upon by representatives of the U. S.
Weather Bureau-and the Corps of Engineers,@is available.

PROBABLE MAXIMUM HURRICANE - A hypo-hurricane that might result
from the most severe combination of hurricane parameters that
is considered reasonably possible in the region involved, if
the hurricane should approach the point under study along a
critical path and at optimum rate of movement. This estimate
is substantially more severe than the SPH criteria.

DESIGN HURRICANE - A representation of a hurricane with specified
characteristics that would produce hurricane surge hydrographs
and coincident wave effects at various key locations along a
proposed project alinement. It governs the project design
after economics and other factors have been duly considered.
The design hurricane may be more or less severe than the SPH,
depending on economics, risk, and local considerations.

IMPERMEABLE GROIN A groin through which sand cannot;pass.

INDIAN SPRING LOW WATER - The approximate leve 1 of the mean-of lower low
waters at spring tides, used principally in the Indian Ocean and
along the east coast of Asia. Also INDIAN TIDE PLANE.

INDIAN TIDE PLANE The datum of INDIAN SPRING LOW WATER.

INLET A short, narrow waterway connecting a bay, lagoon, or similar
body of water with a large parent body of water. -(2) An arm of the
sea (or other other body of water), that is long compared to its
width, and may extend a considerable distance inland. See also
TIDAL INLET.

INLET GORGE - Generally, the deepest region of an inlet channel.

INSHORE (ZONE) - In beach terminology, the zone of variable width extend-
ing from the low water line through the breaker zone. SHOREFACE.
(See Figure A-1.)

INSHORE CURRENT - Any current in or landward of the breaker zone.
INSULAR SHELF - The zone surrounding an island extending from the low
water line to the depth-(usually about 100 fathoms) where there is
a marked or rather steep descent toward the great.depths.
INTERNAL WAVES -@Waves that occur within a fluid whose density changes
with depth, either abruptly at a sharp surface of discontinuity (an
interface) or gradually. Their amplitude is greatest at'the density
discontinuity or, in the case of a gradual density change, somewhere
in the interior of the fluid and not at the free upper'surface where
the surface waves have their maximum amplitude.

IRROTATIONAL WAVE A wave with fluid particles that do n6t...revolve around
an axis through their centers, although the particles,rthemselves may
travel in circular or nearly circular orbits. Irrotationdl waves may
be progressive, standing, oscillatory, or translatory'. For example,
the Airy, Stokes, cnoidal and.solitary wave,theories describe irro-
tational waves. See TROCHOIDAL WAVE..

ISOBATH - A contour line connecting points of equal water depths on a
chart.

ISOVEL PATTERN - See HURRICANE WIND PATTERN.

ISTHMUS - A narrow strip of land, bordered on both sides by water, that
connects two larger bodies of land.

JET To place (as a pile, slab, or pipe) in the ground by means of a
jet of water acting at the lower end.

JETTY - (1) (U. S. usage) On open seacoasts, a structure extending into
a body of water, and designed to prevent shoaling of a channel by
littoral materials, and to direct and confine the stream or tidal
flow. Jetties.are built at the mouth of a river.or tidal inlet to
help deepen and stabilize a channel. (2) (British usage) Jetty is
synonymous with "wharf" or "pier". See TRAINING WALL.

KEY A low insular bank of sand, coral, etc., as one of the islets off
thesouthern coast of Florida, also CAY.

KINETIC ENERGY (OF WAVES) - In a progressive oscillatory wave, a summa-
tion of the energy of motion of the particles within the wave.

KNOLL - A submerged elevation of rounded shape rising less than 1,000
meters from the ocean floor, and of limited extent across the
summit. See SEAMOUNT.

KNOT - The unit of speed used in navigation. It is equal to 1 nautical
mile (6,076.115 feet or 1,852 meters) per hour.

LAGGING See DAILY RETARDATION (OF TIDES).

LAGOON A shallow body of water, as a pond or lake, usually connected
to the sea. (See Figures A-8 and A-9.)

LAND BREEZE - A light wind b/lowing fi@om the land to the sea caused by
unequal cooling of land and water masses.

LAND-SEA BREEZE - The combination of a land breez e and a sea breeze as
a diurnal phenomenon.

LANDLOCKED - An area of water enclosed, or nearly enclosed, by land, as
a bay or a harbor (thus, protected from the sea).

LANDMARK - A conspicuous object natural or artificial, located near or
on land which aids in fixing the position of an observer.

LEADLINE - A line, wire, or cord used in sounding. It is weighted at one
end with a plummet (sounding lead). Also SOUNDING LINE.

LEE - (1) Shelter, or the part or side sheltered or turned away from the
wind or waves. (2) (Chiefly nautical) The quarter or region toward
which the wind blows.

LEEWARD - The direction toward which the wind is blowing; the direction
toward which waves are traveling.

LENGTH OF WAVE - The horizontal distance between similar points on two
successive waves measured perpendicularly to the crest. (See
Figure A-3.)

LEVEE A dike or embankment to protect land from inundation.

LIMIT OF BACKRUSH, LIMIT OF BACKWASH See BACKWASH.

LITTORAL Of or pertaining to a shore, especially of the sea.

LITTORAL CURRENT See CURRENT, LITTORAL.

LITTORAL DEPOSITS Deposits of littoral drift.

LITTORAL DRIFT - The sedimentary material moved in the littoral zone
under the influence of waves and currents.

LITTORAL TRANSPORT - The movement of littoral drift in the lit toral
zone by waves and currents. Includes movement parallel (longshore
transport) and perpendicular (on-offshore transport) to the shore.

LITTORAL TRANSPORT RATE - Rate of transport of sedimentary material
parallel to or perpendicular to the shore in the littoral zone.
Usually expressed in cubic yards (meters) per year. Commonly
used as synonymous with LONGSHORE TRANSPORT RATE.

LITTORAL ZONE - In beach terminology, an indefinite zone extending sea-
ward from the shoreline to just beyond the breaker zone.

LOAD - The quantity of sediment transported by 9 current. It includes
the suspended load of small particles, and the bedload of large
particles that move along the bottom.

LONGSHORE - Parallel to and near the shoreline.

LONGSHORE BAR - A bar running roughly parallel to the shoreline.

LONGSHORE CURRENT - See CURRENT, LONGSHORE.

LONGSHORE TRANSPORT RATE - Rate of transport of-sedimentary material
parallel to the shore. Usually expressed in cubic yards (meters)
per year. Commonly used as synonymous with LITTORAL TRANSPORT.
RATE.

LOOP - That part of a STANDING WAVE where the vertical motion is greatest
and the horizontal velocities are least, LOOPS (sometimes called
ANTINODES) are associated with CLAPOTIS, and with SEICHE action
resulting from wave reflections. (See also NODE.)

LOWER HIGH WATER (LHW) - The lower of the two high waters.of any tidal
day. (See Figure A-10.)

LOWER LOW WATER (LLW) - The lower of the two low waters of any tidal day.
The single low water occurring daily during periods. when the tide
is diurnal is considered to be a lower low water. (See Figure A-10.)

LOW TIDE (LOW WATER, LW) - The minimum elevation reached by each falling
tide. See TIDE. (See Figure A-10.)

LOW WATER DATUM - An approximation to the plane of mean low water that
has been adopted as a standard reference plane. See also DATUM
PLANE and CHART DATUM.

LOW WATER LINE - The intersection of any standard low tide datum plane
with the shore.

LOW WATER OF ORDINARY SPRING TIDES (LWOST) - A tidal datum appearing in
some British publications, based on low water of ordinary spring tides.

MANGROVE - A tropical tree with interlacing prop roots, confined to low-
lying brackish areas.

MARIGRAM - A graphic record of the rise and fall of the tide.

MARSH - An area of soft, wet, or periodically inundated land, generally
treeless and usually characterized by grasses and other low growth.

MARSH, SALT - A marsh periodically flooded by salt water.

MASS TRANSPORT - The net transfer of water by wave action in the direction
of wave travel. See ORBIT.

MEAN DIAMETER, GEOMETRIC - See GEOMETRIC MEAN DIAMETER.

MEAN HIGHER HIGH WATER (MHHW) - The average height of the higher high
waters over a 19-year period. For shorter periods of observation,
corrections are applied to eliminate known variations and reduce
the result to the equivalent of a mean 19-year value.
MEAN HIGH WATER (MHW) - The average height of the high waters over a
19-yeax period. For shorter periods of observations, corrections
are applied to eliminate known variations and reduce the results to
the equivalent of a mean 19-year value. All high water heights are
included in the average where the type of tide is either semidiurnal
or mixed. Only the higher high water heights are included in the
average where the type of tide is diurnal. So determined, mean high
water in the latter case is the same as mean higher high water.

MAN HIGH WATER SPRINGS - The average height of the high waters occurring
at-the time of spring tide. Frequently abbreviated to HIGH WATER
SPRINGS.

MEAN LOWER LOW WATER (MLLW) - The average height of the lower low waters
over a 19-year period. For shorter periods of observations., cor-
rections are applied to eliminate known variations and reduce the
results to the equivalent of a mean 19-year value. Frequently
abbreviated to LOWER LOW WATER.

MEAN LOW,_WATER (MLW) - The average height of the low waters over a 19-
year period. For shorter periods of observations, corrections are
applie..d.,:to -eliminate known variations and reduce the results to the
equivalent of a mean 19-year value. All low water heights are in-
cluded in the average where the type-of tide is either semidiurnal
.or mixed. Only,lower low water heights are included in.the-average
where the type of.tide is diurnal,. So determined, mean low water in
the latter case is the same as mean lower low water.

MEAN LOW WATER SPRINGS The average height of low waters.occurring at
the time of the spring tides. It is usually derived by taking a
plane depressed below the half-tide level by an amount equal to
one-half the spring range of tide, necessary corrections being
applied to reduce the result to a mean value. This plane is used
to a considerable extent for hydrographic work outsidelof the United
States and isthe plane of reference for the Pacific approaches to
the Panama Canal. Frequently abbreviated to LOW WATER SPRINGS.

MEAN SEA LEVEL -,The average height of the surface of the sea for all
stages of the tide over a 19-year period, usually determined from
hourly height readings. Not necessarily equal to MEAN TIDE LEVEL.

MEAN TIDE LEVEL - A plane midway between MEAN HIGH WATER AND WAN LOW
WATER. Not necessarily equal to MEAN SEA LEVEL. Also called
HALF-TIDE LEVEL.

MEDIAN DIAMETER - The diameter which marks the division of a given sand
sample into two equal parts by weight, one part containing all
grains larger than that diameter and the other part containing
grains smaller.

MEGARIPPLE - See SAND WAVE.

MIDDLEGROUND SHOAL - A shoal formed by ebb and flood tides in the middle
of the channel of the lagoon or estuary end of an inlet.

MINIMUM DURATION - See DURATION, MINIMUM.

MINIMUM FETCH - The least,distance in which steady state wave conditions
will develop for a wind@,of given speed blowing a given duration of
time.

MIXED TIDE - A type of tide in which the presence of a diurnal wave is
conspicuous by a large inequality in either the high- or low-water
heights with two high waters and two low waters usually occurring
each tidal day. In Strictness, all tides are mixed, but the name
is usually applied without definite limits to the tide intermediate
to those predominantly semidiurnal and those predominantly diurnal.
(See Figure A-10.)

MOLE - In coastal terminology, a massive land-connected, solid-fill
structure of earth (gene-rally revetted), masonry, or large stone.
It may serve as a breakwater or pier.

MONOCHROMATIC WAVES - A series of waves generated in a laboratory; each
wave has the same length and period.

MONOLITHIC - Like a single stone or block. In coastal structures, the
type of construction in which the structure's component.parts are
bound together to act as one.

MUD - A fluid-to-plastic mixture of finely divided particles of solid
material and water.

'NAUTICAL MILE - The length of a minute of arc, 1/21,600 of an average
great circle of the earth. Generally one minute of latitude is.
considered equal to one nautical mile. The accepted United States
value as of 1 July 1959 is 6,076.115 feet or.1,852 meters., approxi-
mately 1.15 times as long as the statute mile of 5,280 feet. !Also
geographical mile.

NEAP TIDE - A tide occurring near the time of quadrature of the moon with
the sun. The neap tidal range is usually 10 to 30 percent less than
the mean tidal range.

NEARSHORE (ZONE) - In beach terminology an indefinite zone extending.sea-
ward from the shoreline'well beyond the breaker zone.' It'defines
the area of NEARSHORE CURRENTS. (See Figure A-1j.

NEARSHORE CIRCULATION - The ocean circulation pattern composed of the
CURRENTS, NEARSHORE and CURRENTS,- COASTAL. See CURRENT.

NEARSHORE CURRENT SYSTEM - The current system caused primarily by wave
action in and near the breaker zone, and which consists of four
parts: The shoreward mass transport of water; longshore currents;
seaward return flow, including rip currents; and the longshore
movement of the expanding heads of rip currents. (See Figure A-7.)
See also NEARSHORE CIRCULATION.

NECK - (1) The nar.row;band of water flowing seaward through the surf.
Also RIP. (2) The narrow strip of land connecting two larger bodies
of land, as an isthmus.

2 3

NIP - The cut made by waves in a shoreline of emergence.

NODAL ZONE - An area in which the predominant direction of the LONGSHORE
TRANSPORT changes.

NODE - That part of a STANDING WAVE where,the vertical motion is least
and the horizontal velocities are greatest. Nodes are associated
with CLAPOTIS and with SEICHE action resulting from wave reflections.
See also LOOP.

NOURISHMENT - The process of replenishing a beach. It may be brought
about naturally, by longshore transport, or artificially by the
deposition of dredged materials.

OCEANOGRAPHY - The study of the sea, embracing and indicating all
knowledge pertaining to the sea's physical boundaries, the chem-
istry and physics of sea water, and marine biology.

OFFSHORE - (1) In beach terminology, the comparatively flat zone of
variahle width, extending from the breaker zone to the seaward edge
of the Continental Shelf. (2) A direction seaward from the shore.
(See Figure A-1.)

OFFSHORE BARRIER See BARRIER BEACH.

OFFSHORE CURRENT -.(I) Any current in the offshore zone. (2) Any
current flowing away from shore.

OFFSHORE WIND - A wind blowing seaward from the land in the coastal area.

ONSHORE A direction landward.from the sea.

ONSHORE WIND A wind blowing landward from the sea in the coastal area.

OPPOSING WIND In wave forecasting, a wind blowing in a direction opposite
to the ocean-wave advance; generally, same as headwind.

ORBIT - In water waves, the path of a water particle affected by the wave
motion. In deepwater waves the orbit is nearly circular and in
shallow-water waves the orbit is nearly elliptical. In general,
the orbits are slightly open in the direction of wave motion giving
rise to MASS TRANSPORT. (See Figure A-3.)

ORBITAL CURRENT - The flow of water accompanying the orbital movement of
the water particles in a wave. Not to be confused with wave-generated
LITTORAL CIJRRENTS. (See Figure A-3.)

ORTHOGONAL - On a wave-refract ion diagram, a line drawn perpendicularly to
the wave crests. (See Figure A-6.)

OSCILLATION - A periodic motion backward and forward. To vibrate or vary
above and below a mean value.

OSCILLATORY WAVE - A wave in which each individual particle oscillates
about a point with little or no-permanent change in mean position.
The term is cominonly applied to progressive oscillatory waves in
which only the form advances, the individual particles moving in
closed or nearly closed orbits. Distinguished from a WAVE OF
TRANSLATION. See also ORBIT.

-OUTFALL - A structure extending into a body of water for the purpose of
discharging sewage, storm runoff, or cooling water.

OVERTOPPING - Passing of water over the top of a structure as a result
of wave -runup 6.T1 surge action.

OVERWASH - That portion of the aprush that carries over the crest of a
berm or of a structure.

PARAPET - A low wall built along the edge of a structure as on a seawall
or quay.

PARTICLE VELOCITY - Thevelocity induced by wave motion with which a
specific water particle moves within a wave.

PASS -'In hydrographic us age, a navigable channel through a bar, reef,
or shoal, or between closely adjacent islands.

PEBBLES - See SOIL CLASSIFICATION..

PENINSULA - An elongated body of land nearly surrounde d by water, and
connected to a larger body of land.

PERCHED BEACH - A beach or fillet of sand retained above the otherwise
normal profile level by a submerged dike.

PERCOLATION - The process by which water flows through the interstices of
a sediment. Specifically, in wave phenomena, the process by which
wave action forces water through the interstices of the bottom
sediment. Tends to reduce-wave heights.

PERIODIC CURRENT A current caused by the tide-producing forces of the
moon and the sun, a part of the same general movement of the sea that
is manifested in the vertical rise and fall of'the tides.. See 'also
CURRENT, FLOOD and CURRENT, EBB.

PERMANENT CURRENT - A current that runs continuously, independent of the
tides and tenporary causes. Permanent currents include the fresh-
water discharge of a river and the currents that form the general
circulatory systems of the oceans.

PERMEABLE GROIN - A groin with openings large enough to permit passage of
appreciable quantities-'of littoral drift.

PETROGRAPHY 7 The systematic description and classification of rocks.

PHASE - In surface wave motion, a point in the period to which the wave
motion has advanced with. respect.to a given initial reference point.

PHASE INEQUALITY - Variations in the tides or tidal currents associated
with changes in the phase of the moon in relation to the sun.

PHASE VELOCITY - Propagation velocity of an individual wave as opposed to
the velocity of a wave group.

PHI GRADE SCALE - A logarithmic transformation of the.:Wentworth grade
scale for size classifications of sediment grains.based on the
negative logarithm to the base 2 of the particle diameter.
-1092d. See SOIL CLASSIFICATION.

PIER A.structure, usually of open construction, extending out into the
water from the shore, to serve as a landing place, a recreational
facility, etc., rather than to afford coastal protection. In the
Great Lakes, a term sometimes improperly applied to jetties.

PILE A long, heavy timber or section of concrete or metal to be
driven,or jetted into the earth or seabed to serve as a support
or protection.

PILE, SHEET - A pile with a generally slender flat cross section to be
driven into the ground or seabed and meshed or interlocked with like
members to form a diaphragm, wall, or bulkhead.

PILING - A group of piles.

PLAIN, COASTAL See COASTAL PLAIN.

PLANFORM - The outline or shape of a body of water as determined by the
Stillwater line.

PLATEAU A land area (usually extensive) having a relatively level
surface raised sharply above adjacent land on at least one side;
table land. A similar undersea feature.

PLUNGE POINT - (1) For a plunging wave, the point at which the wave curls
over and falls. (2) The final breaking point of the waves just
before they rush up on the beach. (See Figure A-1.)

PLUNGING BREAKER See BREAKER.

POCKET BEACH A beach, usually small, in a coastal reentrant or between
two littoral barriers.

POINT - The extreme end of a cape, or the outer end 'of,any land area
protruding into the water, usually less prominent than a cape.

PORT - A place where vessels may discharge or receive cargo; may be the
entire harbor including its approaches and anchorages, or may be the
commercial part of a harbor where the quays, wharves, facilities for
transfer of cargo, docks, and repair shops are situated.

POTENTIAL ENERGY OF WAVES - In a progressive oscillatory wave, the energy
resulting from the elevation or depression of the watersurface.from
the undisturbed level.

PRISM - See TIDAL PRISM.

PROBABLE MAXIMUM WATER LEVEL - A hypothetical water level (exclusive of
wave runup from normal wind-generated waves) that might result from
the most severe combination of hydrometeorological, geoseismic and,
other geophysical factors that is considered reasonably possible in
the region involved, with each of these factors considered as affect-
ing the locality in a maximum manner.

This level represents the physical response of a body of water
to maximum applied phenomena such as hurricanes, moving squall lines,
other cyclonic meteorological events, tsunamis, and astronomical tide
combined with maximum probable ambient hydrological conditions such
as wave setup, rainfall, runoff, and river flow. It is a water level
with virtually no risk of being exceeded.

PROFILE, BEACH - The intersection of the ground surface with a.vertical
plane; may extend from the top of the dune line to the seaward limit
of sand movement. (See Figure A-1.)

PROGRESSION (of a beach) - See AD VANCE.

PROGRESSIVE WAVE - A wave that moves relative to a fixed coordinate system
in a fluid. The direction in which it moves is termed the direction
of wave propagation.

PROMONTORY - A high point of land projecting into a body of water; a
HEADLAND.

PROPAGATION OF WAVES - The transmission of waves through water.

PROTOTYPE - In laboratory usag,e, the full-scale structure, concept,,or
phenomenon used as a basis for constructing a scale model or copy.

QUAY (Pronounced KEY) - A stretch of paved ban]., or a solid artificial
landing place parallel to the navigable waterway, for'use in loading
and unloading vessels,.

QUICKSAND - Loose, yielding, wet sand which offers no support to heavy
objects. The upward flow of*.th'e water has ',a velocity that eliminates
contact pressures between the sand grains, and causes-the sand-water
mass to behave like a fluid.

RADIUS OF MAXIMUM WINDS - Distance from the eye of a hurrican e, where
surface and wind velocities are zero to the place where surface
wind speeds are maximum.

RAY, WAVE - See ORTHOGONAL.

RECESSION (of a beach) - (1) A continuing landward movement of the
shoreline. (2) A net landward movement of the shoreline over
a specified time. Also RETROGRESSION.

REEF - An offshore consolidated rock hazard to navigation with a least
depth of 10 fathoms (about 20 meters) or less.

REEF, ATOLL See ATOLL.

REEF, BARRIER See BARRIER REEF.

REEF, FRINGING See FRINGING REEF..

.REEF, SAND - Synonymous with BAR.

REFERENCE PLANE - See DATUM PLANE.

REFERENCE STATION - A place for which tidal constants have previously
been determined and which is used as a standard for the comparison
of simultaneoi,:3 observations at a second station; also a station
for which independent daily predictions are given in the tide or
current tables from which corresponding predictions are obtained
for other stations by means of differences or factors.

REFLECTED WAVE - That part of an incident wave that is returned seaward
when a wave impinges on a steep beach, barrier, or bther reflecting
surface.

REFRACTION (OF WATER WAVES) - (1) The process by which the direction of a
wave moving in shallow water at an angle to the contours is changed.
The part of the wave advancing in shallower water moves more slowly
than that part stilladvancing in deeper water, causing the wave
crest to. bend toward alignment with the underwater contours. (2)
The-bending of wave crests by currents. (See Figure A-5.)

REFRACTION COEFFICIENT - The square root of the ratio of the spacing
between adjacent orthogonals in deep water and in shallow water at
a selected point. When multiplied by the SHOALING FACTOR and a
factor for friction and percolation, this becomes the WAVE HEIGHT
COEFFICIENT or the-ratio of the refracted wave height at any point.,
to the deepwater wave height. Also the square root of the.E,NERGY
COEFFICIENT.

REFRACTION DIAGRAM - A drawing showing positions of wave crests and/or
orthogonals in a given .area for a specific deepwater wave period
and direction. (See Figure A-6.)

RESONANCE - The phenomenon of amplification of a free wave or oscilla-
tion of a system by a forced wave or oscillation of exactly equal
period. The forced wave may arise from an impressed force upon
the system or from a boundary condition.

RETARDATION - The amount of time by which corresponding tidal phases
grow later day by day (about 50 minutes).

RETROGRESSION OF A BEACH - (1) A continuing landward movement of the
shoreline. (2) A net landward movement of the shoreline over a
specified time. Also RECESSION.

REVETMENT - A facing of stone, concrete, etc., built to protect a scarp,
embankment, or shore structure against erosion by wave action or
currents.

REYNOLDS NUMBER - The dimensionless ratio of the inertial force to the
viscous force in fluid motion,
LV
Re - V
where L is a characteristic length, v the kinematic viscosity.,
and V a characteristic velocity. The Reynolds number is of im-
portance in the theory of hydrodynamic stability and the origin
of turbulence.

RIA A long, narrow inlet, with depth gradually diminishing inward.

RIDGE, BEACH - A nearly continuous mound of beach material that has been
shaped up by wave or other action. Ridges may occur singly or as
a series of approximately parallel deposits. (See Figure A-7.)
British usage, fulls.

RILL MARKS - Tiny drainage channels in a beach caused by the flow seaward
of water left in the sands of the upper part of the beach after the
retreat of the tide or after the dying down of storm waves.

RIP - A body of water made rough by waves meeting an opposing current,
particularly a tidal current; often found where tidal currents are
converging and sinking.

RIPARIAN - Pertaining to the ba7*s of a body of water.

RIPARIAN RIGHTS - The rights of a person owning land containing or border-
ing on a water course or other body of water in or to its banks, bed,
or waters.

2 9

RIP CURRENT - A strong surface current flowing seaward from the shore.
It usually appears as a.visible band of agitated water and is the
return movement of water piled up on the shore by incoming waves
and wind. With the seaward movement concentrated in a limited
band its velocity is somewhat accentuated. A rip consists of
three parts: the FEEDER CURRENTS flowing parallel to the shore
inside the breakers; the NECK, where the feeder currents converge
and flow through the breakers in a narrow band or "rip"; and the
HEAD, where the current widens and slackens outside the breaker
line. A rip current is often miscalled a rip tide. Also RIP SURF.
See NEARSHORE CURRENT SYSTEM. (See Figure A-7.)

RIP SURF - See RIP CURRENT.

RIPPLE - (1) The ruffling of the surface of water, hence a little curling
wave or undulation. (2) A wave less than 2 inches long controlled
to a significant degree by both surface tension and gravity. See
WAVE, CAPILLARY and WAVE, GRAVITY.

RIPPLES (BED FORMS) - Small bed forms with wavelengths.less than 1 foot
and heights less than 0.1 foot.

RIPRAP_ - A layer, facing, or protective mound of stones randomly placed
to prevent erosion, scour, or sloughing of a structure or embank-
also the stone so used.

ROADSTEAD (Nautical) - A sheltered area of water near shore whe re vessels
may anchor in relative safety. Also road.

ROLLER - An indefinite term, sometimes considered to denote one of a
series of long-crested, large waves which roll in on a shore, as
after a storm.

RUBBLE - (1) Loose angular waterworn stones along a beach. (2) Rough,
irregular fragments of broken rock.

RUBBLE-MOUND STRUCTURE - A mound of ran dbm-shaped and random-placed
stones protected with a cover layer of selected stones or specially
shaped concrete armor units. (Armor units in primary cover layer
,,may be placed in orderly manner or dumped at random.)

RUNNEL - A corrugation or trough formed in the foreshore or in the bottom
just offshore by waves or tidal currents.

RUNUP - The rush of water up a structure or beach on the breaking of a
wave..-Also.UPRUSH.., The,amount of runup is*the vertical height
above stillwater level that the rush of-water reaches.

30.

SALTATION - That method of sand movement in a fluid in which individual
particles leave the bed by bounding nearly vertically and, because
the motion of the fluid is not strong or turbulent enough to retain.
them in suspension, return to the bed at some distance downstream.
The travel path of the particles is a series of hops and bounds.

SALT MARSH - A marsh periodically flooded by salt water.

SAND - See SOIL CLASSIFICATION.

SANDBAR - (1) See BAR. (2) In a river, a ridge of sand built up to or
near the surfa:ce by river currents.

SAND BYPASSING Set BYPASSING, 'SAND.

SAND REEF - Synonymous with BAR.

SAND WAVE (or MEGARIPPLE) - A large wavelike sediment feature composed
of sand in very shallow water. Wavelength may reach 100 meters;
amplitude is about 0.5 meters.

SCARP - See ESCARPMENT.

SCARP, BEACH An almost vertical slope along the beach.caused.by erosion
by wave action. It may vary in height from a few inches to several
feet, depending on wave action and the nature and composition of,
the beach. (See Figure A-1.)

SCOUR - Removal of underwater material by waves and currents, especially
at the base or toe of a shore structure.

SEAS - Waves caused by wind at the place and time of observation.

SEA STATE - Description of,the sea surface with regard to wave action.
Also called s'tate of sea.

SEA BREEZE A light wind blowing from the sea toward the land caused
by unequal heating of land and water masses.

SEA CLIFF - A cliff situated at the seaward edge of the coast.

SEA LEVEL - See MEAN SEA LEVEL.
SEAMOUNT -- An elevation rising more than 1,000 meters above the ocean
floor, and of limited extent across the summit.

SEA PUSS - A dangerous longshore current;,a:rip,current caused by return
flow; loosely,-@tht submerged channel or inletthrough a bar caused
by those currents.

SEASHORE The SHORE of a sea or ocean.

SEAWALL A structure separating land and water areas, primarily
designed to prevent erosion and other damage due to wave action.
See also BULKHEAD.

SE ICHE - (1) A standing wave oscillation of an enclosed water body that
continues, pendulum fashion, after the cessation of the originating
force, which may have been either seismic or atmospheric. (2) An
oscillation of a fluid body in response to a disturbing force having
the same frequency as the natural.frequency of the fluid system.
Tides are now considered to be seiches induced primarily by the
periodic forces caused by the sun and moon. (3) In the Great Lakes
area, any sudden rise in the water of a harbor or a lake whether or
not it is oscillatory. Although inaccurate in a strict sense, this
usage is well established in-the Great-Lakes area.

SEISMIC SEA WAVE (TSU NAMI) - A long-period wave caused by an underwater
seismic disturbance or volcanic eruption. Commonly misnamed
"tidal wave".

SEMIDIURNAL TIDE - A tide with two high and two low waters in a tidal
day with comparatively little diurnal inequality (See Figure A-10.)

SET OF CURRENT - The direction toward which a current flows.

SETUP, WAVE - Superelevation of the water surface over normal surge
elevation due to onshore mass transport of the water by wave
action alone.

SETUP, WIND - See WIND SETUP.

SHALLOW WATER - (1) Commonly, water of such a depth that surface waves
are noticeably affected by bottom topography. It"is customary,to
consider water of depths less than one-half the surface wavelength
as shallow water. See TRANSITIONAL ZONE and DEEP WATER. (2) More
strictly, in hydrodynamics with regard to progressive gravity waves,
,water in which the depth is less than 1/25 the wavelength. Also
called VERY SHALLOW WATER.

SHEET PILE - See PILE, SHEET.

SHELF, CONTINENTAL - See CONTINENTAL SHELF

SHELF, INSULAR - See INSULAW SHELF

SHINGLE - (1) Loosely and commonly, any beach material coarser than
ordinary gravel, especially any having flat or flattish pebbles.
(2) Strictly and accurately, beach material of smooth, well-rounded
pebbles that are roughly the same size. The spaces between pebbles
are not filled with finer materials. Shingle often gives out a
musical sound when stepped on.

SHOAL (noun) - A detached elevation of the sea bottom, comprised of any
material except rock or coral, which may endanger surface navigation.

SHOAL (verb) - (1) To become shallow gradually. (2) To cause to become
shallow. '(3) To proceed from a great er to a lesser depth of water.

SHOALING COEFFICIENT - 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 COEFFICIENT and REFRACTION
COEFFICIENT.

SHORE - 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.)

SHOREFACE - 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) and Figure A-1.

SHORELINE - The intersection of a specified plane of water with-the shore
or beach. (e.g., the highwateT shoreline would be the intersection
of the plane of mean high water with the shore or beach.) -The line
delineating the shoreline on U. S. Coast and Geodetic Survey nau-
tical charts and surveys approximates the mean high water line.

SIGNIFICANT WAVE - A statistical term relating to the one-third highest
waves of a given wave group and defined by the average@oftheir
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 es't'ablish .
the character of the higher waves will.record values-whi,ch approxi-
mately fit the definition 6f.the significant wave.

SIGNIFICANT WAVE HEIGHT - Theaverage height of theone-third highest
waves of a given wave group. Note that the composition.of the
highest wav.'es depends upon the extent to which the.lower waves,are
considered. In wave record analysis, the.average height of the
highestone-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 tak6n 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 re-.
curring of the larger well-defined waves in the record under study.

SILT - See SOIL CLASSIFICATION.

SINUSOIDAL WAVE An oscillatory wave having the form of a sinusoid.

SLACK TIDE-(SLACK WATER) - The state of a tidal current when its velocity
is, near zero, especially the moment when a reversing current changes
direction.and its velocity is zero. Sometimes considered the inter-
mediate period between ebb and flood currents during which the ve-
locity of the currents is less than 0.1 knot. See STAND OF TIDE.

SLIP A berthing.space between two piers.

SLOPE The degree of inclination to the horizontal. Usually expressed
as a ratio, such as 1:25 or I on 25, indicating I unit vertical rise
in 25 units of horizontal distance; or in a decimal fraction (0.04);
degrees (2* 181); or percent (4%).

SLOUGH See BAYOU.

SOIL CLASSIFICATION (size) - An arbitrary division of a continuous scale
of grain sizes such that each scale unit or grade may serve as a
convenient class interval-for conducting the analysis or for ex-
pressing the results of an analysis. There are many classifications
used, the two most often used are shown graphically on the next page.

SOLITARY WAVE.- A wave consisting of a single elevation (above the origi-
nal water surface), its height not necessarily small compared to the
depth, and neither followed nor preceded by another elevation or de-
pression of the water surfaces.

SORTING COEFFICIENT A coefficient used in describing the distribution of
grain sizes in a'sample of unconsolidated material. It is defined as
so = 'QI/Q3.1 where Q, is the diameter (in millimeters) which has
75 perc.ent of the@cumulative size-frequency (by weight) distribution
Ismaller than itself and 25 percent larger than itself, and Q3 is that
diameter having 25 percent smaller and 75 percent larger than itself.

SOUND (noun) - (1) A wide waterway between the mainland and an island, or
a wide waterway connecting two sea areas. See also STRAIT. (2) A
relatively long arm of the sea or ocean forming a channel between
an island and a mainland or connecting two larger bodies, as a sea
and the ocean, or two parts of the same body; usually wider.and more
extensive than a strait.

SOUND (verb) To measure the depth of the water.

SOUNDING - A measured depth of water. On hydrographic charts the sound-
ings are adj,usted to a specific plane of reference (SOUNDING DATUM).

SOUNDING DATUM.- The plane to which soundings are referred. See also
CHART DATUM.

GRAIN SIZE SCALES
(Soil Classification)

Wentworth Phi Units Grain U.S. Std. Unified Soil
Scale Diameter, Sieve Classification
(Size Description) D (mm) Size (USC)

Boulder
-8 256 Cobble

Cobble 76.2 311

-6 64.0 Coarse
19.0 3/411 Fine Gravel
Pebble 4.76 No. 4

-2 @4. 0 Coarse
Granule
-1 2.0 No. 10
Very Coarse 0 1.0 SaInd
Coarse Medium
1 0.5
Medium 0.142 No. 40
Sand
2 0.25
Fine Fine
3 0.125

Very Fine 0.074 No. 200

4 0.0625
Silt
8 0.00391 Silt or Clay
Clay
12 0.00024
Colloid

-1092 D (mm)

SOUNDING LINE - A line, wire, or cord used in sounding. It is weighted
at one end with a plummet (sounding' lead). Also LEADLINE.

SPILLING BREAKER.- See BREAKER.

SPIT - A small point of land or a narrow shoal projecting into a body of
water from the shore. (See Figure A-9.)

SPRING TIDE A tide that occurs at or near the time of new or full moon
(syzygy), and which rises highest and falls lowest from the mean
sea level.

STANDARD PROJECT HURRICANE - See HYPOTHETICAL HURRICANE.

STAND OF TIDE -An interval at high or low water when there is no sensible
change in the height of the tide. The water level is stationary at
high and''low water for only an instant, but the change in level near
these times is so slow that it is not usually perceptible. See SLACK
TIDE.'

STANDING WAVE type of wave in which the surface of the water oscillates
vertically'between fixed points, called nodes, without progression.
The points of maximum vertical rise and fall are called antinodes
or loops. At the nodes, the underlying water particles exhibit no
vertical motion, but maximum horizontal motion. At the antinodes,
the underlying water particles have no horizontal motion but maximum
vertical motion. They may be the result of two equal progressive
wave trains'traveling through each other in opposite directions.
Sometimes called CLAPOTIS or STATIONARY WAVE.

STATIONARY WAVE -'A wave of essentially stable form which does not move
with respect to a selected reference point; a fixed swelling.
Sometimes called STANDING WAVE.

STILLWATER LEVEL The elevation that the surface of the water would
assume if all wave action were absent.

STOCKPILE - Sand piled on a beach foreshore to nourish downdrift beaches
.by natural littoral currents or forces. See. FEEDER BEACH.

STONE, DERRICK - Stone heavy enough to require handling individual pieces
by mechanical means, generally 1 ton and up.

STORM SURGE - A rise above normal water'level on the open coast due to
the action of wind stress on the water surface. Storm surge result-
ing from a hurricane also includes that rise in level due to atmos-
pheric pressure reduction as well as that due to wind stress. See
WIND SETUP.

STORM TIDE - See STORM SURGE.

STRAIT - A relatively narrow waterway between two larger bodies of water.
See also SOUND.

STREAM - (1) A course of water flowing along a.bed in the earth. (2) A
current in the sea formed by wind action, water density differ-
ences, etc. (Gulf Stream). See also CURRENT, STREAM.

SURF The wave activity in the area between the shoreline and the
outermost limit of breakers.

SURF BEAT - Irregular oscillations of the nearshore water level, with
periods of the order of several minutes.

SURF ZONE - The area between the outermost breaker and the limit of
wave uprush. (See Figures A-2 and A-5.)

SURGE (1) The name applied to wave motion with a period intermediate
between that of the ordinary wind wave and that of the tide, say
from 1/2 to 60 minutes. It is of low height; usually less than
0.3 foot. See also SEICHE. (2) In fluid flow, long interval
variations in velocity and pressure, not necessarily periodic,
perhaps even transient in nature. (3) See STORM SURGE.

SURGING BREAKER See BREAKER.

SUSPENDED LOAD (1) The material moving in suspension in a fluid, being
kept up by the upward components of the turbulent currents or by
colloidal suspension. (2) The material collected in or computed
from samples collected with a suspended load sampler. .(A suspen-
ded load sampler is a sampler which attempts to secure a sample
of the water with.its sediment load without separating the sedi-
ment from.the water.) Where it is necessary to distinguish
between the two meanings given above, the first one may be called
the "true suspended load".

SWALE - The depression between two beach ridges.

SWASH - The rush of water up onto the beach face following thebreaking
of a wave. Also UPRUSH, RUNUP. (See Figure A-2.)

SWASH CHANNEL - (1) On the open shore, a channel cut by flowing water in
its return to the parent body (e.g., a rip channel). (2) A sec-
ondary channel passing through or shoreward of an inlet or river
bar. (See Figure A-9.)

SWASH MARK - The thin wavy line of fine sand, mica scales, bits of sea-
weed, etc.,' left by the uprush when it recedes from its upward
limit of movement on the beach face.

SWELL - Wind-generated-waves that have traveled out of their generating
area. Swell characteristically exhibit s a more regular and longer
period, and has flatter crests than waves within their fetch
(SEAS).

SY NOPTIC CHART - A chart showing the distribution of meterological
conditions over a given area at a given time. Popularly called
a weather map.

SYZYGY - The two points in the moon's orbit when the moon is in con-
junction or opposition to the sun relative to the earth; time of
new or full moon in the cycle of phases.

TERRACE - A horizontal or nearly horizontal natural or artificia:1 topo-m
graphic feature interrupting a steeper slope, sometimes occurring
in a series.

THALWEG - In hydraulics, the line joining the deepest points of an
inlet or stream channel.

TIDAL CURRENT - See CURRENT, TIDAL

TIDAL DATUM - See CHART DATUM and DATUM PLANE.

TIDAL DAY - The time of the rotation of the earth with respect to the
moon, or the interval between two successive upper transits of the
,moon over the meridian of a place, approximately 24.84 solar hours
(24 hours and 50 minutes) or 1.035 times the mean solar day. (See
Figure A-10.) Also called lunar day.

TIDAL FLATS - Marshy or muddy land areas which are covered and un-
covered by the rise and fall of the tide.

TIDAL INLET - (1) A natural inlet maintained by tidal flow. (2)
Loosely, any inlet in which the tide ebbs and flows. Also TIDAL
OUTLET.

TIDAL PERIOD - The interval of time between two consecutive like phases
of the tide. (See Figure A-10.)

TIDAL POOL - A pool of water remaining on a beach or reef after reces-
sion of the tide.

TIDAL PRISM.- The total amount of water that flows into a harbor or
estuary or out again with movement of the tide, excluding any
freshwater flow.'

TIDAL RA NGE - The difference in height between 'consecutive high and low
(or higher,high and lower low) waters. (See Figure A-10.)

TIDAL RISE - The 'height of tide as referred to the datum of a chart.
(See Figure A-10.)

TIDAL WAVE - (1) The wave motion of the tides. (2) In popular usage,
any unusually high and destructive water level along a shore. It
usually refers to STORM-SURGE or TSUNAMI.

TIDE - The periodic rising and falling of the water that results from
gravitational attraction of the moon and sun and other astronomi-
cal bodies acting upon the rotating earth. Although the accompany-
ing horizontal movement of the water resulting from the same-cause
is also sometimes called the tide, it is preferable to designate
the latter as TIDAL CURRENT, reserving the name TIDE for the ver-
tical movement.

TIDE, DAILY RETARDATION OF - The amount of time by which correspond-
ing tides grow later day by day (about 50 minutes).

,TIDE, DIURNAL - A tide with one high water and one low water in a
tidal day. (See Figure A-10)

TIDE, EBB - See EBB TIDE.

TIDE, FLOOD See FLOOD TIDE

TIDE, MIXED See MIXED TIDE.

TIDE, NEAP-- See NEAP TIDE.

TIDE, SEMIDIURNAL - See SEMIDIURNAL TIDE.

TIDE, SLACK - See SLACK TIDE.

TIDE, SPRING - See SPRING TIDE.

TIDE STATION - A place at which tide observations are being taken. it
is called a primary tide station when continuous observations are
to be taken over a number of years to obtain basic tidal data for
the locality. A secondary tide station is-one operated ovey'a:
short period of time to obtain data for a specific purpose.

TIDE, STORM - See STORM SURGE.

TOMBOLO - A bar or spit that connects or "ties" an island to the main-
land or to another island. (See Figure A-9.)

TOPOGRAPHY - The configuration of a surface, including its relief, the
position of its streams.,;roads.,'building-, etc.

TRAINING WALL - A wall or jetty to direct current flow.

TRANSITIONAL ZONE (TRANSITIONAL WATER) - In regard to progressive
gravity waves, water whose depth is less than 1/2 but more than
1/25 the wave length. Often called SHALLOW WATER.

TRANSLATORY WAVE - See WAVE OF TRANSLATION.

TRANSPOSED HURRICANE - See HYPOTHETICAL HURRICANE.

TROCHOIDAL WAVE - A theoretical, progressive oscillatory wave first
proposed by Gerstner in 1802 to describe the surface profile and
particle orbits of finite amplitude, nonsinusoidal waves. The
wave form is that of a prolate cycloid or trochoid, and the fluid
particle motion is rotational as opposed to the usual irrotational
particle motion for waves generated by normal forces. See IRRO-
TATIONAL WAVE

TROPICAL CYCLONE See HURRICANE

TROPICAL STORM - A tropical cyclone with maximum winds less than 75
mph.

TROUGH OF WAVE - The lowest part of a wave form between successive
crests. Also that part of a wave below stillwater level. (See
Figure A-3.)

TSUNAMI - A long-period wave caused by an underwater disturbance such
as a volcanic eruption or earthquake. Commonly.miscalled "tidal
wavell.

TYPHOON - See HURRICANE.

UNDERTOW- A seaward current neat the bottom on a sloping inshore zone.
It is caused by the return, under the action of gravity, of the
water carried up on the shore by waves. Often a misnomer for
RIP CURRENT.

UNDERWATER GRADIENT - The slope of the sea bottom. See also SLOPE.

UNDULATIO14 - A continuously propagated motion to and fro, in any fluid
or elastic medium, with no permanent translation of the particles
themselves.

UPCOAST - In United States usage, the coastal direction generally
trending toward the north.

UPDRIFT - The direction opposite that of the predominant movement of
littoral materials.

UPLIFT - The upward water pressure on the base of a structure or
pavement.

UPRUSH - The rush of water up onto the beach following the breaking of
a wave. Also SWASH, RUNUP. (See Figure A-2.)

VALLEY, SEA - A submarine depression of broad valley form without the
steep side slopes which characterize a canyon.

VALLEY, SUBMARINE - A prolongation of a land valley into or across a
continental or insular shelf, which generally gives evidence of
having been formed by stream erosion.

VARIABILITY OF WAVES - (1) The variation of heights and periods be-
tween individual waves within a wave train. (Wave trains are not
composed of waves of equal height and period., but rather of-
heights and periods which vary in a statistical manner.) (2) The
variation in direction of propagation of waves leaving the gen-
erating area. (3) The variation in height along the crest,
usually called "variation along the wave".

VELOCITY OF WAVES - The speed at which-an individual wave advances.
See WAVE CELERITY.

VISCOSITY - (or internal friction) That molecular property of a
fluid that enables it to support tangential stresses for a
finite time and thus to resist deformation.

WATERLINE - A juncture of land and sea. This line migrates, changing
with the tide or other fluctuation in the water level. Where
waves are present on the beach, this line is also known as the
limit of backrush. (Approximately the intersection of the land
with the stillwater level.)

WAVE - A ridge, deformation, or undulation of the surface of a liquid.

WAVE AGE - The ratio of wave speed to wind speed.

WAVE, CAPILLARY - See CAPILLARY WAVE.

WAVE CELERITY - Wave speed.

WAVE CREST See CREST OF WAVE.

WAVE CREST LENGTH See CREST LENGTH, WAVE

WAVE, CYCLOIDAL - See CYCLOIDAL WAVE.

WAVE DECAY - See DECAY OF WAVES.

WAVE DIRECTION - The direction from which a wave approaches.

WAVE FORECASTING - The theoretical determination of future wave char-
acteristics, usually from observed or predicted meteorological
phenomena.

WAVE GENERATION - See.GENERATION OF WAVES.

WAVE, GRAVITY See GRAVITY WAVE.

WAVE GROUP - A series of waves in which the wave direction, wave-
length, and wave height vary only slightly. See also GROUP
VELOCITY.

WAVE HEIGHT - The vertical distance between a crest and the preceding
trough. See also SIGNIFICANT WAVE HEIGHT. (See Figure A-3.)

WAVE HEIGHT COEFFICIENT - The ratio of the wave height at a selected
point to the-deepwater wave height. The refraction coefficient
multiplied by the shoaling factor.

WAVE HINDCASTING See HINDCASTING, WAVE.

WAVE, IRROTATIONAL See IRROTATIONAL WAVE.

WAVELENGTH - The.horizontal distance between similar points on.two
successive waves measured perpendicular to the crest. (See
Figure A-3.) 7-

WAVE, MONOCHROMATIC See MONOCHROMATIC WAVE.

WAVE,, OSCILLATORY - See OSCILLATORY WAVE.

WAVE PERIOD - The time for a wave crest to traverse a distance equal
to one wave length. The time for two successive wave crests to
pass a fixed point. See also SIGNIFICANT WAVE PERIOD.

WAVE, PROGRESSIVE See PROGRESSIVE WAVE.

WAVE PROPAGATION The transmission of waves through water.

WAVE RAY - See ORTHOGONAL.

WAVE, REFLECTED - That part of an incident wave that is returned sea-
ward when a wave impinges on a steep beach., barrier, or other re-..
flecting surface.

WAVE REFRACTION See REFRACTION OF WATER WAVES.

WAVE SETUP - See SETUP, WAVE.

WAVE, SINUSOIDAL - An oscillatory wave having the form of a sinusoid.

WAVE, SOLITARY - See SOLITARY WAVE

WAVE, STANDING - See STANDING WAVE.

WAVE STEEPNESS - The ratio of the wave height to the wavelength.

WAVE TRAIN - A series of waves fromthe same direction.

WAVE OF TRANSLATION - A wave in which the water particles are per-
manently desplaced to a significant degree in the direction of
wave travel. Distinguished from an OSCILLATORY WAVE.

WAVE, TROCHOIDAL - See TROCHOIDAL WAVE.
WAVE TROUGH /_ The lowest part of a wave form between successive crests.
Also that part of a wave below stillwater level.

WAVE VARIABILITY - See VARIABILITY OF WAVES.

WAVE VELOCITY The speed at which an individual wave advances.

WAVE, WIND - See WIND WAVES.

WAVES, INTERNAL - See INTERNAL WAVES.

WEIR JETTY An updrift jetty with a low section or weir over which
littoral drift moves into a predredged deposition basin which is
dredged periodically.

WHARF A structure bui.lt on the shore of a harbor, river, or canal,
so that vessels may lie alongside to receive and discharge cargo
and passengers..

WHITECAP On the crest of a wave, the white froth caused by wind.

WIND CHOP See CHOP.

WIND, FOLLOWING See FOLLOWING WIND.

WIND, OFFSHORE A wind blowing seaward from the land in a coastal
area.

WIND, ONSHORE A wind blowing landward from the sea in a coastal area.'

WIND, OPPOSING See OPPOSING WIND.

WIND SETUP - (1) The vertical rise in the stillwater level on the lee-
ward side of a body of water caused by wind stresses on the sur-
'face of the water. (2) The difference in stillwater levels on
the windward and the leeward sides of a body of water caused by
wind stresses on the surface of the water. (3) Synonymous with
WIND TIDE and STORM SURGE. STORM SURGE is usually reserved for
use on the ocean and large bodies of water. WIND SETUP is
usually reserved for use on reservoirs and smaller bodies of
water. (See Figure A-11.)

WIND TIDE See WIND SETUP, STORM SURGE.

WINDWARD The direction from which the wind is blowing.

WIND WAVES - (1) Waves being formed and built up by the wind. (2)
Loosely, any wave generated by wind.

Coastal area

Nearshore zone
(defines area of nearshors, currents)
Coast Beach or shore
Backshore I Fartshow Inshore or Shorefoce -Offshore
or (extends through breaker zone
Beach
Face
Bl-ff
r
--e.r)P'_t -*rm
.. 7..rp we ter level Breakers
Crest of ber

Ordinary low waftr- Is

Plunge point
Bottom

Figure A-1. Beach Profile-Related Terms.

surf or Breaker zone

wo peak up but
do not break on
this bor at NO tift
Tr&Wowv waves POO
tj wher line Re-formed Outer line Waves fla"an
of oscillatory

wolarlevel

MLLW Breaker dspthwl.3H

sloch face

bow bar

Outer bar Deep bor
Ilener bar. low lids) (Outer bor. W Me)

Figu re A-2. Schematic Diagram of Waves in the Breaker Zone.
m

Direction of Wave Travel
Wave Crest L: Wavelength ve He
H = Wo ight

Length
Region Wave Tr fillwater Level
-Trough Length--@
Region d = Depth

Ocean Bottom

.... .. . ..........
.............. . ..... .
. . .......
...........
. . ....... . .........
...........

Directio n of Wave Travel--,,- Orbit Diameter Ho)
Lo
Ho

I ode

Still Water Level

LO/
2 Direction of orbital movement of water
d ' I/
particles in different parts of a deep
water wove.

Small m .otion of water below L 0/2

Direction of Wove. Travel

d < 0/2

..................
......... ......... ....
............... ............... . .. ........ . .
................... . ..................
................ ...
............... .........................
..............
... .......... . .................. ::%% .....
... . ...... . ............
Beach gross shows the direction of movement
o of water particles under various parts of a
.shallow water wove.

I Wi ego 1, 1953)
Figure A-3. Wave Characteristics and Direction of
T-
A@Wl Trou7gh
@Stillwoter

Water Particle.Movement.

BREAKING
FOAM POINT
4

AAJT
T 11

BEACH BOTTOM

BEACH IS USUALLY VERY @FLAT

SKETCH SHOWING THE GENERAL CHARACTER
SPILLING BREAKER OF SPILLING BREAKERS

0 MN
1& 1-0
RK;

BREAKING
POINT
. . . . . . . FOAM 4 3 2
@S i

BEACH BOTTOM

BEACH IS USUALLY STEEP

SKETCH SHOWING THE GENERAL CHARACTER
PLUNGING BREAKER OF PLUNGING BREAKERS

FOAM LINE FOAM LINE
FOAM LINE OF 2
O@ 4 OF 3
40@ �11.L@L AT
_K_ _gIL L I t!E
4

BEACII 801.1,0

BEACH IS USUALLY VERY STEEP
-T-W7
SURGING BREAKER SKETCH SHOWING THE GENERAL CHARACTER
OF SURGING BREAKERS

lEIoth photographs and diagrams of thethree types of breakers,are
presented above. the sketches consist of a series of profiles of the
wave form as if appears before breaking , during brea-king and after
breaking. The num.ber.s opposite the prof (le .1ines.indicate the relative
times of occurences.
(Wiegel,1953)

Figure A-4. Breaker Types.
5 4 1@1@
'L
T

B AC. BOTTOM

-! W3 -,

NARROW
SURF ZONE

J,
7

Pt. Pinos, California

Waves mov ing over a submarine ridge concentrate to give large
wove heights on a point.

IV
z
iz -
6V
WIDE
ZONE
SPI@F

0
M4,11 '5'
P I N
NARR(
',',SURF Z NE

SURF ZONE f@

L V7

NOUN"

Haltmoon Boy, California Purisimo Pt., Californio
Note the increasing width of the surf zone with increasing degree Refraction of waves around a headland produces low waves and
of exposure to the South. a narrow surf zone where bending is greatest.
(Wiegel, 1953)
Figure A-5. Refraction of Waves.

T I
I

@q
_X
3 H C

4,
B
LOW WAVES WVw
IN -COVE
Gov
Ing
M
4"
P
p F,
IE,
T

JkL ;,
o o,:,4
HIGH" WAVES T
W
0 N POINT j,- , , " @
7#1
7
k
-2
iu
a

ll;@g"7

06.0aft"CE OP
GOT"O*OkA%$
PRODUCE$ L W
WAVES M TMIS
AREA

ARENA
COVE

QC"vtR*tkCE Of CATHOGONALS
PRODUCE$ "I** WAVES IN TNIS
ARE,%

- - - OEVTM CONYOUNSL
IN lAlMO.S
WAIJE FRONTS I SECOND 06-100

SCALE
Al Wiege 1 19 53) 1
Figure A-6. Refraction Diagram.

At, t

2AF
AF@&k
xu@ A 09
A

K- MASS TRANSPORT OF WAVES
S Fj i
ZO@R
0 E
01 NEC
LUNII ORE
"'FEEDER CURRE-
DCLU
ocg T CURRENT
SHORE L

q!,-t
11- , e, -`& q'-
K4 ,
!R@ Y
P
Y, A

&J@

Al ,

Figure A-,7,. Beach Features.

3AR

a-mado
gig"

ek,

lie

(Wiegel, 1953)

Figure A-8. Shoreline Features.

'Y"

x
oews
GOO

Cuspote Bar
Boymouth Bar

Kotama Boy Swosh Channel

04@6ore bar
River
mouth
Boymouth Bar bar Bars

"All

Port Orchord

JL
Spits Single Tornbolo

Logoon

Double Tornbolo Barrier Beach

Figure A-9. Bar and Beach Forms. (from D. W. Johnson, Shore Process
GOO" e'*s

Boymouth Bar
3@MOBOY
..........

'10

and Shoreline Development, 1919, published by John Wiley
& Sons, Inc.)

0 6 12 18 0 6 12 18 0 6 12 hours

-
12 ft. I I I .
-10 Tidal Day
-8 Tidal Periocl@
6

2
O-Datum
--2

SEMI DIURNAL

0 6 12 18 0 6 12 18 0 6 12 hours
-12 ft. I I
- 10 High Tide Flood Tide
8

-4

-2
O-Datum \27 .01
---2 \@ L
-4 ft.

DIURNAL

0 6 12 18 0 6 12 18 0 6 12 hours
-Q ft. Tidal Day igher High WateF
-10 Tidal Period
8
-6 Tidal Rise Lower High Water
-4

-2

-0-Dotum-
--2 J Tidal Range Higher Low Wo'ter
--4 ft. Lower Low Water

MIXED (WIS 1,1953)

Figure A-10. Types of Tides.
H
N

06 /Water surface with east wind
/Water surface with west wind
0.4
0.
Ol

Ic'-O I/,-- W1 d setup Wind setup
(Deflnition 1) (Definition 2

Water level

tom
20
'm 301
j

Nodal line
BUFFALO

AM14ERSTS
L AKE ERIE

TOLEDO

SCALE
LEVELA04D 0 so ioa, Krm

(Hellstrom, 19411

Figure A-11. Setup or Wind Tide.

AS
. .. ... .

MIT,

"i sR

. . . . . . .----

Figure A-12. Collapsing Breaker.
'n,

UNCLASSIFIED
Security Classi.fication
DOCUMENT CONTROL DATA - R & D
(Security classification of title, body of ab tract and.! !.be entered when th overal repoiltjo classifie I
I .ORIGINATING ACTIVITY (Corporate author) REPORT S12CURITV CLASSIFICATION
Coastal Engineering Research Center ;(CERC) UNCLASSIFIED
Corps of Engineers, Department of .,.the Army 12b. GROUP
Washington, D.C. 20016
3. REPORT TITLE
A GLOSSARY OF COASTAL ENGINEERING. TERMS

4. DESCRIPTIVE NOTES (Type of report and inclusive date&)

S. AUT HOR(S) (Fitattidlime, middle initial, lastname)

Richard,H. Allen
6. REPORT DATE 7a. TOTAL NO. OF PAGES 17b. NO. OF REFS
June 1972 55 (12 figures) 5-
80. CONTRACT OR GRANT NO. 9a. ORIGINATOR-S REPORT NUWBERIS)
Miscellaneous Paper 2-72
b. PROJECT NO.

9b. OTHER REPORT NO(S) (Any OthOr-mbers thatmay, be assigned
this report)

10. OtSTRI,BUTION STATEMENT

This documenthas been approved for public release and sale; its distribution is
unlimited..

11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY

13. ABSTRACT

A glossary of terms usedby coastal engineers is presented. The terms apply to such
subjects.as waves, tides, littoral prodesses, shore protection, shore structures,
and,coastal geomorphology. Primary sources are cited.

FORK PLACIRS 00 FORM 1473, 1 JAN 04, WHICH IS
DDINOV061473 :a-S0j-ZTK FOR ARMY USK. UNCL.ASSIFIED
Security Clealtification

IINCT Is, .01,01,T11i; Rssifi cation
KEY WOROS LIN A LINK 8 LINK C
RO I- E WT ROLE WT ROLE WT

Glossary of Terms
Waves
Tides
Littoral Processes
Shore Protection
Shore Structures
Coastal Geomorphology
F@lossa3@

UNCLASSIFIED

Security Classification

--------- --------------- ---------------------------

U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms U.S. ARMY COASTAL ENGRG RESEARC14 CENTER, CE I . Glossary of Terms
WASHINGTON, D.C. 20016 2. Waves WASHINGTON, D.C. 20016 2. Waves
3. Tides 3. Tides
A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes
by Richard H. Allen 55 pages including S. Shore Protection by Richard H. Allen 5S pages including S. Shore Protection
12 figures. June 1972 6. Shore Structures 12 figures. June 1972 6. Shore Structures
7. Coastal 7. Coastal
MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology

I. Title 1. Title
TI. CERC Staff II. CERC Staff

A glossary of terms used by coastal engineers is presented. The A glossary of terms used by coastal engineers is presented. The
terms apply to such subjects as waves, tides, littoral processes, shore terms apply to such subjects as waves, tides, littoral processes, shore
protection, shore structures, and coastal geomorphology. Primary protection, shore structures, and coastal geomorphology. Primary,
sources are cited. sources are cited.

U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms
WASHINGTON, D.C. 20016 2. Waves WASHINGTON, D.C. 20016 2. Waves
3. Tides 3. Tides
A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes
by Richard H. Allen 55 pages including S. Shore Protection by Richard H. Allen 55 pages including S. Shore Protection
12 figures. June 1972 6. Shore Structures 12 figures. June 1972 6. Shore Structures
7. Coastal 7. Coastal
MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology

I. Title I. Title
II. CERC Staff 11. CERC Staff

A glossary of terms used by coastal engineers is presented. The A glossary of terms used by coastal engineers is presented. The
terms apply to such subjects as waves, tides, littoral processes, shore terms apply to such subjects as waves, tides, littoral processes, shore
protection, shore structures, and coastal geomorphology. Primary protection, shore structures, and coastal gcomorphology. Primary
sources are cited. sources are cited.

---------------

U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1 . Glossary of Terms
WASHINGTON, D.C. 20016 2. Waves WASHINGTON, D.C. 20016 2. Waves
3. Tides 3. Tides
A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes
by Richard H. Allen 55 pages including S. Shore Protection by Richard H. Allen 5S pages including S. Shore Protection
12 figures. June 1972 6. Shore Structures 12 figures. June 1972 6. Shore Structures
7. Coastal 7. Coastal
MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology

I. Title 1. Title
Il. CERC Staff 11. CERC Staff

U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms U.S. ARMY COASTAL ENGRG RESEARCH CENTER, CE 1. Glossary of Terms
WASHINGTON, D.C. 20016 2. Waves WASHINGTON, D.C. 20016 2. Waves
3. Tides 3. Tides
A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes A GLOSSARY OF COASTAL ENGINEERING TERMS 4. Littoral Processes
by Richard H. Allen 55 pages including S. Shore Protection by Richard H. Allen 55 pages including 5. Shore Protection
12 figures. June 1972 6. Shore Structures 12 figures. June 1972 6. Shore Structures
7. Coastal 7. Coastal
MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology MISCELLANEOUS PAPER 2-72 UNCLASSIFIED Geomorphology

1. Title I. Title
11, CERC Staff II. CERC Staff

A glossary of terms used by coastal engineers is presented. The A glossary of terms used by coastal engineers is presented. The
terms apply to such.subjects as waves, tides, littoral processes, shore terms apply to such subjects as waves, tides, littoral processes, shore
protection, shore structures, and coastal geomorphology. Primary protection, shore structures, and coastal geomorphology. Primary
sources are cited. sources are cited,

COASTAL ZONE
INFORMATION CENTER