Glossary Hydraulic Engineering terms


Abutment landhoofd That part of the valley side against which the dam is constructed, or the approach embankment in case of bridges which may intrude some distance into the waterway.
Accretion Aanzanding Build up of material solely by the action of the forces of nature through the deposition of waterborne or airborne material.
Aggradation Aanzanding A build up or raising of the channel bed due to sediment deposition
Alongshore Parallel aan de kustlijn of dichtbij de kustlijn Parallel to and near the shoreline; LONGSHORE.
Amplitude amplitude (1) The magnitude of the displacement of a wave from a mean value. An ocean wave has an amplitude equal to the vertical distance from still-water level to wave crest. For a sinusoidal wave, the amplitude is one-half the wave height. (2) The semirange of a constituent tide.
Angle of repose hoek van het natuurlijke talud
Anisotropic Anisotropisch Property of the mineral fabric of a rock block or piece of rock such that its strength and visual appearance is not the same in all directions.
Antinode Buik (van trilling) See LOOP.
Apron stortebed, bodembescherming (lett. beschermlap, Layer of stone, concrete or other material to protect the toe of a structure against scour.
Aquifer aquifer
Aquifer watervoerende laag
Aquitard aquitard underground layer with low permeability
Armour layer Toplaag Protective layer on rubble mound breakwater composed of armour units
Armour unit Bekledingselement A relatively large quarrystone or concrete shape that is selected to fit specified geometric characteristics and density. It is usually of nearly uniform size and usually large enough to require individual placement. In normal cases it is used as primary wave protection and in case of rock it is placed in layers that are at least two units thick.
armouring beschermen, pantseren
Artificial nourishment Zandsuppletie Supplementing the natural supply of beach material to a BEACH, using imported material.
Backrush Terug- of afloop The seaward return of the water following the uprush of the waves. For any given tide stage the point of farthest return seaward of the backrush is known as the LIMIT of BACKRUSH or LIMIT BACKWASH.
Backwash terugstroming (in golfoploop) (1) See BACKRUSH. (2) Water or waves thrown back by an obstruction such as a ship, breakwater, or cliff.
Backwater curve Stuwkromme The longitudinal profile of the water surface in an open channel where the depth of flow has been increased by an obstruction as a WEIR or a DAM across the channel, by increase in channel roughness, by decrease in channel width or by a decrease of the bed gradient.
bank oever
bar bank (zandbank)
bar zandbank
barrage stuw, kering A barrage built across a (tidal) river, comprising a series of gates which when fully open allow the flood to pass without appreciably increasing the flood level upstream of the barrage.
Barrier Stuw The function of a barrier is to control the water level. It consists of a combination of a concrete or a steel structure with or without adjacent ROCKFILL DAMS.
Bastion A massive GROYNE, or projecting section of seawall normally constructed with its crest above water level.
Bathymetry Diepteligging, bodemprofiel The measurement of depths of water in oceans, seas, and lakes; also information derived from such measurements.
Beach Strand By common usage, the zone of BEACH MATERIAL that extends landward from the lowest water line to the place beyond the high water line, where there is a marked change in material or physiographic form, or to the line of permanent vegetation.
Beach replenishment Zandsuppletie Supplementing the natural supply of beach material to a BEACH, using imported material.
bed bodem
Bed load Bodemtransport The quantity of sediment moving along the bed by rolling, jumping or sliding with at least intermittent contact.
Bed protection Bodembescherming A (rock) structure on the sea bed or on the bed of a river or estuary in order to protect the underlying bed against erosion due to current and/or wave action.
Benchmark A permanently fixed point of known elevation. A primary benchmark is one close to a tide station to which the tide staff and tidal datum originally are referenced.
bend scour bochterosie Erosion in (the other part of) a river bed
Berm Berm 1) Relative small mound to support or key-in an ARMOUR LAYER. 2) A horizontal step in the sloping profile of an EMBANKMENT.
Berm Breakwater Rubble mound structure with horizontal BERM of ARMOUR STONES at about sea side water level, which is allowed to be (re)shaped by the waves.
Bifurcation Splitsingspunt Location where a river separates in two or more reaches or branches.
Blanket bodembescherming A layer or layers of graded fine stones underlying a breakwater, GROYNE or rock EMBANKMENT to prevent the natural bed material from being washed away.
Bottom Bodem The ground or bed under any body of water; the bottom of the sea. The nature of the bottom gives 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 Bolder A rounded rock more than 10 inches in diameter. A stone larger than a cobblestone. See SOIL CLASSIFICATION.
boulder clay keileem clay type formed in the ice age, including rocks from moraines; very resistant against erosion.
Boundary condition randvoorwaarde
boundary depth grensdiepte Waterdepth in case of critical flow, i.e. the froude number is one: hb=(q^2/g)^(1/3) in which hb is the bourndary depth and q the discharge in m^2/s. The boundary depth is sometimes called limiting depth
bow boeg Front part of a ship
Braided river Vlechtende rivier A river type with multiple channels separated by shoals, bars and islands.
Braiding belt Area extending on both sides along a braided river out to the extreme historic alignments of the river banks.
Breach Bres breach in a levee, dike or sand dune
Breaker Breker, brekende golf A wave breaking on a shore, over a reef, etc. Breakers may be classified into four types. See also Breakerdepth
Breaker parameter Iribarrengetal dimensionless parameter to descibe wave-structure interaction, the ratio between structur slope and wave steepness
Breakerdepth Breekdiepte The still-water depth at the point where a wave breaks. Also called BREAKING DEPTH.
Breakwater Golfbreker A structure protecting a shore area, harbor, anchorage, or basin from waves.
Breastwork Timber structure generally parallel to coast
brushwood rijshout thin, flexible branches of wood (usally Osier)
Bull nose Substantial lip or protuberance at the top of the seaward face of a wall, to deflect waves seaward
Buoyancy Opdrijving The resultant of upward forces, exerted by the water on a submerged or floating body, equal to the weight of the water displaced by this body.
Bypassing Omleiden van sediment 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 movement as well as movement caused by man.
Caisson Caisson Concrete box-type structure
Canal Geul, kanaal, gracht An artificial watercourse cut through a land area for such uses as navigation and irrigation andesigned for low velocity flow
Cascading dike failures trapsgewijs falen van opeenvolgende dijken
Catchment stroomgebied The area which drains naturally to a particular point on a river, thus contributing to its natural discharge
Celerity Golfsnelheid Wave speed.
Channel Geul, kanaal, zeestraat (1) A natural or artificial waterway of perceptible extent which either periodically or continuously contains moving water, or which forms a connecting link between two bodies of water. (2) The part of a body of water deep enough to be used for navigation through an area otherwise too shallow for navigation. (3) A large strait, as the English Channel. (4) The deepest part of a stream, bay, or strait through which the main volume or current of water flows.
Characteristic value karakteristieke waarde
Chart Zeekaart Hydrographic map; see also CHART DATUM
Chart datum Referentiepeil The plane or level to which soundings (or elevations) or tide heights are referenced (usually LOW WATER DATUM). The surface is called a tidal datum when referred to a certain phase of tide. To provide a safety factor for navigation, some level lower than MEAN SEA LEVEL is generally selected for hydrographic charts, such as MEAN LOW WATER or MEAN LOWER LOW WATER. See DATUM PLANE.
Chop The short-crested waves that may spring up quickly in a moderate breeze, and which break easily at the crest. Also WIND CHOP.
Clapotis Staande Golf 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 non-breaking wave train from a structure with a face that is vertical or nearly vertical. Full clapotis is one with 100 percent reflection of the incident wave; partial clapotis is one with less than 100 percent reflection.
Clay Klei See SOIL CLASSIFICATION.
clear weir, perfect weir, clear overfall Volkomen overlaat
Clogging Dichtslibben
Cnoidal Cnoïdaal Cnoidal waveA type of wave in shallow water (i.e., where the depth of water is less than 1/8 to 1/10 the wavelength). The surface profile is expressed in terms of the Jacobian elliptic function cn u; hence the term cnoidal.
Coastline Kustlijn (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 rolsteen Cobblestone, see SOIL CLASSIFICATION.
Cofferdam Kistdam A temporary watertight structure enclosing all or part of the construction area so that construction can proceed in the dry.
coherent samenhangend
cohesive cohesief Soil material consisting of fine particles which are in some way bonded (in contradiction to loose sand) like clay
collapse in elkaar storten Collapsing breakers - breaking occurs over lower half of wave, with minimal air pocket and usually no splash up. Bubbles and foam present.
collide botsen
Compacting verdichten
concrete beton
Confluence Samenvloeiing The junction of two or more river reaches or branches.
Confluene scour Erosion at the CONFLUENCE of rivers
Consolidation consolidatie
constriction vernauwing
construction bouw, uitvoering, constructie
Contour Dieptelijnen A line on a map or chart representing points of equal elevation with relation to a DATUM. It is called an ISOBATH when connecting points of equal depth below a datum. Also called DEPTH CONTOUR.
Convergence Convergentie (1) In refraction phenomena, the decreasing of the distance between orthogonals in the direction of wave travel. Denotes an area of increasing wave height and energy concentration. ¶(2) In wind-setup phenomena, the observed increase in setup (above the increase that would occur in an equivalent rectangular basin of uniform depth), that is caused by changes in plan form or depth. Also the decrease in basin width or depth causing such an increase in setup.
coping dekzerk coverstone covering masonry work
Coral Koraal (1) (Biology) Marine coelenterates (Madreporaria), solitary or colonial, which form a hard external covering of calcium compounds or other materials. The corals that form large reefs are limited to warm, shallow waters, while that 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 calcareous secretions, such as bryozoans and hydrozoans.
Core Boorkern A vertical cylindrical sample of the bottom sediments from which the nature and stratification of the bottom may be determined.
Core Kern The most inner part of a breakwater or a dam, usually consisting of rock (all sizes) or sand
Correlation correlatie
Cover layer Toplaag The outer layer used in a revetment system as protection against external hydraulic loads
CPT (cone penetration test) sondering
Creep kruip
Crenulate An indented or wavy shoreline beach form, with the regular, seaward pointing parts rounded rather than sharp, as in the CUSPATE type.
Crest Golftop (1) Crest of wave, wave crest: The highest part of a wave. (2) That part of the wave above still-water level. Crest lenght, sometimes called crest width, is the length of the wave crest, perpendcular to the wave movement.
crest kruin top part of a construction
Critical head difference kritisch stijghoogteverschil
Crown kruin Top of a structure
Crown wall Borstwering Concrete superstructure on a RUBBLE MOUND.
culvert duiker underground connection for water of limited size
Cumulative distribution function verdelingsfunctie
Current Stroom, stroming A flow of water Coastal Current: One of the offshore currents flowing generally parallel to the shoreline in the deeper water beyond and near the surf zone. These are not genetically related to waves and the resulting surf, but may be related to tides, winds, or distribution of mass. >>Ebb current: The tidal current away from shore or down a tidal stream. Usually associated with the decrease in the height of the tide. >>Flood current: The tidal current toward shore or up a tidal stream. Usually associated with the increase in the height of the tide. >>Littoral current: Any current in the littoral zone caused primarily by wave action; e.g., LONGSHORE CURRENT, RIP CURRENT. See also CURRENT, NEARSHORE. >>Longshore current:The littoral current in the breaker zone moving essentially parallel to the shore that is usually generated by waves breaking at an angle to the shoreline. >>Tidal current: The alternating horizontal movement of water associated with the rise and fall of the tide caused by the astronomical tide-producing forces.
cusp interferentie piek
Cuspate Gepiekt Form of beach shoreline involving sharp seaward pointing cusps (normally at regular intervals) between which the shoreline follows a smooth arc.
Dam Dam Structure built in rivers or estuaries, basically to separate water at both sides and/or to retain water at one side. See also BARRAGE.
Damage function schadefunctie
Damping demping
Datum Referentievlak See also CHART DATUM.Datum plane is 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 hydrographic charts: >>MEAN LOW WATER--Atlantic coast (US), Argentina, Sweden, and Norway >>MEAN LOWER LOW WATER--Pacific coast (US) >>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 BENCHMARK.
debris rommel, afval
Decay afname 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 calm, or region of lighter winds. In the process of decay, the significant wave height decreases and the significant wavelength increases.
Deep water Diep water Water so deep that surface waves are little affected by the ocean bottom. Generally, water deeper than one-half the surface wavelength is considered deep water. Compare SHALLOW WATER.
Depth Diepte The vertical distance from a specified tidal datum to the sea floor. See also DEEP WATER and SHALLOW WATER
Design storm Ontwerpstorm Sea walls will often be designed to withstand wave attack by the extreme design storm. The severity of the storm (i.e. RETURN PERIOD) is chosen in view of the acceptable level of risk of damage or failure.
design water level ontwerpwaterstand water level used in the design, usually a waterlevel with a given return probability
Deterministic deterministisch
Diffraction Diffractie The phenomenon by which energy is transmitted laterally along a wave crest. When a part of a train of waves is interrupted by a barrier) such as a breakwater) the effect of diffraction is manifested by propagation of waves into the sheltered region within the barrier's geometric shadow.
dike (dyke) dijk A long, low embankment with a height usually less than four to five metres and a length more than ten or fifteen times the maximum height. Usually applied to protect land from flooding. (Dike is to be preferred above Dyke)
dike circle dijkring system of dikes (or high grounds) surronding a polder, protecting this polder against inundation
Discharge debiet amount of water flowing trough a cross section per unit of time (m3/s)
Discontinuity Any actual or incipient fracture plane in a rock mass including bedding planes, laminations, foliation planes, joints and fault planes.
Ditch sloot
Ditch greppel
Diurnal Enkeldaags Having a period or cycle of approximately one tidal day. A diurnal tide is a tide with one high water and one low water in a tidal day.
Divergence Divergentie (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 observed decrease in setup under that which would occur in an equivalent rectangular basin of uniform depth) that is caused by changes in plan form or depth. Also the increase in basin width or depth causing such a decrease in setup.
Diversion channel A WATERWAY used to divert water from its natural course. The term is generally applied to a temporary arrangement e.g. to by-pass water round a DAM site during construction.
Downdrift Benedenstrooms The direction of predominant movement of LITTORAL DRIFT along the shore
downrush terugstromen (in golfoploop)
drag slepen - trekken - stromingsweerstand
Drawdown snelle daling waterniveau
Drowned flow Verdonken overlaat see SUBCRITICAL FLOW
dune foot duinvoet transition from the sloping dune face to the beach
Durability The ability of a rock to retain its physical and mechanical properties (i.e. resist DEGRADATION) in engineering service.
Duration Tijdsduur In wave forecasting, the length of time the wind blows in nearly the same direction over the FETCH (generating area).
Duricrust A hard layer formed at a present or past desert surface where salts carried in solution by capillary action have precipitated and cemented the surface layer sediments.
Dynamic equilibrium Short term morphological changes that do not affect the MORPHOLOGY over a long period.
Ebb Eb - vallend water Ebb current: The tidal current away from shore or down a tidal stream and usually associated with the decrease in height of the tide.¶ Ebb tide:The period of tide between high water and the succeeding low water; a falling tide.
Echo Echo see also: Echo sounder
Echo sounder Echolood An electronic instrument used to determine the depth of water by measuring the time interval between the emission of a sonic or ultrasonic signal and the return of its echo from the bottom.
Eddy Wervel, neer A circular movement of water formed on the side of a main current. Eddies may be created at points where the main stream passes projecting obstructions or where two adjacent currents flow counter to each other. Also EDDY CURRENT.
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.
Effective stress effectieve korrelspanning
Embankment Dijk, kade An artificial bank such as a mound or dike generally built to retain (hold back) water or to carry a roadway. An embankment is generally higher than a DIKE.
Energy Energie See energy coefficient
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 shallow-water point to the distance between the same pair of orthogonals in deep water. Also the square of the REFRACTION COEFFICIENT.
Equi-potential line potentiaallijn
equilibrium evenwicht
Erosion Erosie 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.
Estuary zeearm
Exit gradient uittreegradient
Exit point uittreepunt
Expected annual damage verwachte jaarlijkse schade
External safety externe veiligheid
Extreme value extreme waarde
Facing A coating of a different material, masonry or brick, for architectural or protection purposes e.g. stonework facing, brickwork facing (concrete dam) or an impervious coating on the upstream slope of the DAM.
Factor of safety veiligheidsfactor
faggot wiep Bundle of brushwood, with a circumference of approx. 50 cm, as part of a mattress.
Failure mechanism faalmechanisme
Failure mode faalmechanisme
Failure probability Faalkans The probability that a construction is no longer able to perform its function (is not the probability of collapse)
Failure probability Bezwijkkans Probablity that a structure fails
Fairway Vaargeul The parts of a waterway that are open and unobstructed for navigation. The main travelled part of a waterway; a marine thoroughfare.
fascine mattress zinkstuk mattress made of brushwood
Fathom Vadem A unit of measurement used for soundings equal to 1.83 meters (6 feet).
Fathometer The copyrighted trademark for a type of echo sounder.
Fault tree foutenboom
Feeder Feeder beach, beach constructed to nourish a longshore transport in order to prevent erosion upstream of the feeder beach
Fetch Strijklengte The area in which SEAS are generated by a wind having a fairly constant direction and speed. Sometimes used synonymously with FETCH LENGTH, which is the horizontal distance, (in the direction of the wind) over which a wind generate SEAS of creates WIND SETUP.
Filter Filter Intermediate layer, preventing fine materials of an underlayer from being washed through the voids of an upper layer.
Flaws Discontinuities and voids within a piece of rock.
Flood Vloed, opkomend water The period of tide between low water and the succeeding high water; a rising tide. A flood current is the tidal current toward shore or up a tidal stream, which is usually associated with the increase in the height of the tide. Note1:Flood is not the moment of high water. Note2: In river engineering the term FLOOD is also used for the whigh water wave coming down a river during peak runoff.
Flood defence waterkering
Flood defence act wet op de waterkering
Flood risk overstromingsrisico
Flood routing The attenuating effect of storage on a flood passing through a valley, a CHANNEL or RESERVOIR by reason of a feature acting as a control e.g. a reservoir with a spillway capacity less than the flood inflow or the widening or narrowing of a valley.
Flood wall Keermuur Wall, retired from the seaward edge of the sea wall crest, to prevent water from flowing on to the land behind.
Floodplain uiterwaard Part of the riverbed flooded during high river run-off
Flotsam veek
Flow net vierkantennet
Flow regime Combinations of river discharge and corresponding water levels and their respective (yearly or seasonally) averaged values and characteristic fluctuations around these values.
flow slide zettingsvloeiing
Forecasting Wave forecasting: the theoretical determination of future wave characteristics, usually from observed or predicted meteorological phenomena.
Foreshore Vooroever 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.
Fracture toughness The characteristic level of stress intensity ahead of a crack tip that is required to propagate the new crack catastrophically through the mineral fabric of the rock.
Fragility curve kwetsbaarheidscurve Functios indicating the conditional failure probablility as a function of the load
Freeboard waakhoogte height of a defence above the still water level
Freeboard Waakhoogte, vrijboord The additional height of a structure above design high water level that is added to prevent overflow. Also, the vertical distance between the water level and the top of the structure at a given time. On a ship, the distance from the waterline to main deck or gunwale.
Friction angle wrijvingshoek
Froude Froude-getal The Froude number is the dimensionless ratio of the inertial force to the force of gravity for a given fluid flow. It may be given as Fr = V /Lg where V is a characteristic velocity, L is a characteristic length, and g the acceleration of gravity--or as the square root of this number.
Gabion schanskorf a basket or cage filled with earth or rocks and used especially in building a support or abutment or shoreline
Geotextile Geotextiel A synthetic fabric which may be woven or non-woven used as a FILTER or separation layer.
Gradient Gradient, verhang 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.
gradient verhang change in value over a length difference. Height difference divided by distance in height gradient
Gradings Gradering Distribution, with regard to size or weight, of individual stones within a bulk volume. Heavy, light and fine gradings are distinguished.
Gradual closure Geleidelijke sluiting Method in which the final gap is closed gradually either by the VERTICAL or the HORIZONTAL CLOSURE method or a combination of both methods. This method includes the use of large, massive CAISSONS to be placed on a SILL.
Granular filter Granulair filter A band of granular material which is incorporated in an EMBANKMENT dam and is graded so as to allow SEEPAGE to flow across or down the filter zone without causing the migration of the material from zones adjacent to the FILTER.
Gravel Grind - kiezel See SOIL CLASSIFICATION.
Gravity Zwaartekracht see GRAVITY WAVE
Gravity wave Zwaartekrachtsgolf A wave whose velocity of propagation is controlled primarily by gravity. Water waves more than 2 inches long are considered gravity waves. Waves longer than 1 inch and shorter than 2 inches are in an indeterminate zone between capilarry and GRAVITY WAVES. See RIPPLE.
Groin Strandhoofd US term for a Groyne, a shore protection structure built (usually perpendicular to the shoreline) to trap littoral drift or retard erosion of the shore.
Group Groep see GROUP VELOCITY
Group velocity Groepssnelheid The velocity of a wave group. In deep water, it is equal to one-half the velocity of the individual waves within the group.
Groyne (beach groyne) Strandhoofd dam perpendicular to the beach with the purpose to decrease longshore transport
Groyne (river groyne) Krib (rivierkrib) short dam in a river perpendicular to the embankment with the purpose to concentrate the flow in the middle of the river
Groyne system Serie strandhoofden A series of groynes acting together to protect a section of beach. Commonly called a groyne field.
Harbour Haven (In US: Harbor). Any protected water area affording a place of safety for vessels. See also PORT.
Head stijghoogte
Head difference stijghoogteverschil
heave opdrijven heave of the topsoil becasue of overpressure in the underground
heave heave unstable sand, quicksand, caused by upwards flowing water
heel post achterhar vertical beam in a lock door (mitre door) at the side of the lock wall
HHW HHW HIGHER HIGH TIDE: 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.
High Hoog see HIGH WATER LINE, HW, HHW, HLW
High water line Hoogwaterlijn Strictly speaking, the intersection of the plane of mean high water with the shore. The shoreline delineated on the nautical charts of the National Ocean Service approximates the high water line. For specific occurrences, the highest elevation on the shore reached during a storm or rising tide, including meteorological effects.
Hindcast Hindcast The use of historic synoptic wind charts to calculate characteristics of waves that probably occurred at some past time.
Hinterland achterland
HLW HLW HIGHER LOW TIDE: The higher of two low waters of any tidal day.
hull romp (van schip)
Hurricane Orkaan, wervelstorm An intense tropical cyclone in which winds tend to spiral inward toward a core of low pressure. Maximum surface wind velocities equal or exceed 33.5 meters per second (75 mph or 65 knots) for several minutes or longer at some points. TROPICAL STORM is the term applied if maximum winds are less than 33.5 meters per second. The Hurricane track is the line of movement of the eye through an area
HW Hoog water (HW) HIGH WATER: The maximum elevation reached by each rising tide. See TIDE.
HWOST HW niveau bij normaal springtij HIGH WATER OF ORDINARY SPRING TIDE: A tidal datum appearing in some British publications that is based on high water of ordinary spring tides.
Hydraulic conductivity doorlatendheid
Hydraulic roughness hydraulische weerstand
Hydrography Hydrografie (1) The configuration of an underwater surface including its relief, bottom materials, coastal structures, etc. (2) The description and study of seas, lakes, rivers, and other waters.
Hypohurricane A representation of a hurricane, with specified characteristics, that is assumed to occur in a particular study area, following a specified path and timing sequence.
impermeable niet poreus, ondoorlatend
impervious ondoordringbaar
impinge treffen, botsen
incipient motion begin van beweging The moment sand or stones start to move under flow conditons
Individual risk individueel risico
inflection buigen
Inlet Zeegat (1) 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 body of water) that is long compared to its width and may extend a considerable distance inland. See also TIDAL INLET.
Inner berm binnenberm Brm at the inner side of a dike to give extra support and/or to prevent upwelling of water at the inner side of a dike
interface grensvlak, overgang
Intredepunt entrance point
Intrusion length indringingslengte
Inundation overstroming
Iribarren number Iribarrengetal dimensionless parameter to descibe wave-structure interaction, the ratio between structur slope and wave steepness
Irrotational Rotatievrij Irrotanional wave: a wave with fluid particles that do not revolve around an axis through their centers, although the particles themselves may travel in circular or nearly circular orbits. Irrotational waves may be PROGRESSIVE, STANDING, OSCILLATORY, or TRANSLATORY. For example, the Airy, Stokes, cnoidal, and solitary wave theories describe irrotational waves. Compare TROCHOIDAL WAVE.
jet straal
Jetty Havenhoofd, pier, steiger, strekdam (1) (United States usage) On open seacoasts, a structure extending into a body of water, which is 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 mouths of rivers or tidal inlets to help deepen and stabilize a channel. ¶(2) (British usage) WHARF or PIER. See TRAINING WALL.
Kinematic viscosity kinematische viscositeit
Kinetic Kinetisch Kinetic energy of a wave: In a progressive oscillatory wave, a summation of the energy of motion of the particles within the wave.
Knot Knoop The unit of speed used in navigation equal to 1 nautical mile (6,076.115 feet or 1,852 meters) per hour. (approximately equal to 0.5 m/s)
leach uitlogen
Lead Lood Lead line, or sounding line; a line, wire, or cord used in sounding, which is weighted at one end with a plummet (sounding lead)
leakage lek
Leakage factor lekfactor
Leakage length leklengte
Lee Lij (beschutting) (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 Lijzijde The direction toward which the wind is blowing; the direction toward -which waves are traveling.
Levee dijk A dike or embankment to protect land from inundation (typical US term,usually along a river, but in New Orleans area also seadikes).
LHW LHW Lower high water: The lower of the two high waters of any tidal day.
Limit state function betrouwbaarheidsfunctie
liquefaction zettingsvloeiing saturated sand behaving like a fluid
Littoral Along the coast, see also LITTORAL DRIFT and LITTORAL TRANSPORT
Littoral drift langsstroom Flow of water along the coast by obliquely breaking waves
Littoral transport Kusttransport Sediment transport causesd by littoral drift in the littoral zone (by waves and currents). Includes movement parallel (longshore transport) and perpendicular (on-offshore transport) to the shore. The littoral transport rate is the rate of transport of sedimentary material parallel or perpendicular to the shore in the littoral zone. Usually expressed in cubic meters (cubic yards) per year. Commonly synonymous with LONGSHORE TRANSPORT RATE.
LLW LLW Lower low water: 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.
Load Belasting, gehalte The quantity of sediment transported by a current. It includes the suspended load of small particles and the bed load of large particles that move along the bottom.
Longshore Parallel to and near the shoreline; see also LITTORAL
Loop Buik 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. Compare NODE.
Low water line Laagwaterlijn The intersection of any standard low tide datum plane with the shore.
LW LW Low water: The minimum elevation reached by each falling tide. See TIDE.
LWOST Low water of ordinary sprint tide: A tidal datum appearing in some British publications that is based on low water of ordinary spring tides.
Macro instability macroinstabiliteit
Mangrove Mangrove A tropical tree with interlacing prop roots that is confined to low-lying brackish areas.
Marsh Moeras An area periodically flooded by water; a saltmarsh is periodically flooded by salt water, usually above normal high water
Mass transport Massatransport The net transfer of water by wave action in the direction of wave travel. See also ORBIT.
mattress zinkstuk bedprotection made of brushwood and geotextile to prevent erosion of the subsoil due to currents and waves
Mean Tide level A plane midway between MEAN HIGH WATER and MEAN LOW WATER. This is not necessarily equal to MEAN SEA LEVEL. Also HALF-TIDE LEVEL.
Median Mediaan see MEDIAN DIAMETER
Median diameter Mediane 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 all grains smaller.
MHHW GHHW Mean Higher High Water: 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.
MHW GHW Mean High Water: The average height of the high waters over a 19-year 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.
MHWS GHWS Mean High Water Spring: The average height of the high waters occurring at the time of spring tide. Frequently abbreviated to HIGH WATER SPRINGS.
Micro instability microinstabiliteit
Middle ground shoal A shoal formed by ebb and flood tides in the middle of the channel of the lagoon or estuary end of an inlet.
mithre post voorhar vertical beam in a lock door (mitre door) at the place where the two doors connect
mixed see MIXED TIDE
Mixed tide Gemengd getij 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
MLLW GLLW Mean Lower Low Water: The average height of the lower low-waters, over a 19-year 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. Frequently abbreviated to LOWER LOW WATER.
MLW GLW Mean Low Water: The average height of the low waters over a 19-year 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 low water heights are included 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.
MLWS GLWS Mean Low Water Spring: 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 outside of the United States and is the plane of reference for the Pacific approaches to the Panama Canal. Frequently abbreviated to LOW WATER SPRINGS.
Momentum Impuls product of mass and velocity
Monochromatic Monochromatisch see MONOCHROMATIC WAVE
Monochromatic wave Regelmatige golf A series of waves generated in a laboratory; each wave has the same length and period.
Monolithic mopnmolitisch 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.
Multi-layered safety meerlaagsveiligheid
MWL NAP Mean Water Level or Mean Sea Level: The average height of the surface of the sea for all stages of the tide over a 19-year period. This is usually determined from hourly height readings and is not necessarily equal to MEAN TIDE LEVEL.
Nautical Nautisch see NAUTICAL MILE
Nautical mile Zeemijl 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 1,852 meters (6,076.115 feet), approximately 1.15 times as long as the U.S. statute mile of 5,280 feet. Also geographical mile.
Neap see NEAP TIDE
Neap tide Dood tij 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.
Node knoop (van trilling) 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. Compare LOOP.
nozzle tuit
Oblique schuin
Oceanography The study of the sea, embracing and indicating all knowledge pertaining to the sea's physical boundaries, the chemistry and physics of seawater, and marine biology.
Offshore (1) In beach terminology, the comparatively flat zone of variable width, extending from the breaker zone to the seaward edge of the Continental Shelf. (2) A direction seaward from the shore.
Orbit Cirkelvormige baan 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 al;so ORBITAL MOVEMENT
Orbital movement Orbitaalbeweging The flow of water accompanying the orbital movement of the water particles in a wave. Not to be confused with wave-generated LITTORAL CURRENTS.
orifice opening van de uitstroming
Orthogonal Golfstraal, orthogonaal On a wave-refraction diagram, a line drawn perpendicularly to the wave crests. WAVE RAY.
Oscillation Trilling (1) A periodic motion backward and forward. (2) Vibration or variance above and below a mean value. see also OSCILLATORY WAVE
Oscillatory wave Haalgolf A wave in which each individual particle oscillates about a point with little or no permanent change in mean position. The term is commonly applied to progressive oscillatory waves in which only the form advances, the individual particles moving in closed or nearly closed orbits. Compare WAVE OF TRANSLATION. See also ORBIT.
osier revetment rijspakwerk
Overflow overloop
Overload overbelasting
Overtopping Overslag Passing of water over the top of a structure as a result of wave runup or surge action.
Overwash Overslag That portion of the uprush that carries over the crest of a berm or of a structure.
Parapet Borstwering A low wall built along the edge of a structure such as a seawall or quay.
Particle see PARTICLE VELOCITY
Particle velocity Deeltjessnelheid The velocity induced by wave motion with which a specific water particle moves within a wave.
Peat veen
Permeability Doorlatendheid
permeable doorlatend construction where water may flow through; usually with small openings to prevent passing of sand
Permeable groyne Doorlatende krib of strandhoofd A groyne with openings large enough to permit passage of appreciable quantities of LITTORAL DRIFT.
Phreatic level freatisch niveau
Phreatic level stijghoogte
pier pijler, pier
piping piping (pijpvorming) formation of a "pipe" by erosion under a hard surface by ground water flow
pitch zetten (plaveien) Placing blocks in a regular pattern in a revetment
Pivot taats
pivot taatskom place where the mitre door is turning in
plunge duiken
Plunging Plunging breakers--crest curls over air pocket; breaking is usually with a crash. Smooth splash up usually follows.
Pore water pressure waterspanning
Port Haven A place where vessels may discharge or receive cargo. It may be the entire harbour, including its approaches and anchorages, or only the commercial part of a harbor, where the quays, wharves, facilities for transfer of cargo, docks, and repair shops are situated.
post har vertical beam in a lock door, see also mitre post and heel post
Potential see POTENTIAL WAVE ENERGY
Potential potentiaal
Potential wave energy In a progressive oscillatory wave, the energy resulting from the elevation or depression of the water surface from the undisturbed level.
Prism Prisma See TIDAL PRISM.
Probability density function dichtheidsfunctie
Probability distribution kansverdeling
Probability distribution function verdelingsfunctie
Probability of exceedance overschrijdingskans
profile (measurement profile) raai line on which data are colected, eg. water depth, currents
Progressive wave Lopende golf A wave that moves relative to a fixed co-ordinate system in a fluid. The direction in which it moves is termed the direction of wave propagation.
Propagation see WAVE PROPAGATION
propeller race schroefstraal
Prototype Prototype In laboratory usage, the full-scale structure, concept, or phenomenon used as a basis for constructing a scale model or copy.
protrude uitsteken
quarry steengroeve an excavation or pit from which building stone is obtained by cutting, blasting, etc.
Quarrystone Breuksteen Any stone processed from a quarry.
quay kade (Pronounced KEY) A stretch of paved bank or a solid artificial landing place parallel to the navigable waterway, for use in loading and unloading vessels.
quicksand drijfzand Loose, yielding, wet sand which offers no support to heavy objects. The upward flow of the water has a velocity that eliminates contact pressures between the sand grains and causes the sand-water mass to behave like a fluid.
Recession Achteruitgang, erosie Recession of a beach (1) A continuing landward movement of the shore line. (2) A net landward movement of the shoreline over a specified time. Also RETROGRESSION.
rectifier gelijkrichter
Refelcted wave Teruggekaatste golf That part of an incident wave that is returned seaward when a wave impinges on a steep beach, barrier, or other reflecting surface.
Refraction Refractie 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 still advancing in deeper water, causing the wave crest to bend toward alignment with the underwater contours. (2) The bending of wave crests by currents. see also REFRACTION COEFFICENT
Refraction coefficient Refractiecoëfficient The square root of the ratio of the distance between adjacent orthogonals in deep water to their distance apart 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 ENERGY COEFFICIENT.
Reliability betrouwbaarheid
Relief well verlichtingswel
Residual risk restrisico
Residual strength reststerkte
Resonance Resonantie, opslingering The phenomenon of amplification of a free wave or oscillation 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.
Retain keren
Retention basin retentiebekken a basin used to manage stormwater runoff to prevent flooding and downstream erosion, and improve water quality in an adjacent river, stream, lake or bay.
Return period herhalingstijd
Revetment Steenzetting, bekleding A facing of stone, concrete, etc., built to protect a scarp, embankment, or shore structure against erosion by wave action or currents.
Reynolds Reynoldsgetal Reuynolds number: The dimensionless ratio of the inertial force to the viscous force in fluid motion, where L is a characteristic length, n the kinematic viscosity, and V a characteristic velocity. The Reynolds number is important in the theory of hydrodynamic stability and the origin of turbulence.
Rip Mui see RIP CURRENT
Rip current Muistroom 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.
Riprap breuksteen, stortsteen A protective layer or facing of quarrystone, usually well graded within wide size limit, randomly placed to prevent erosion, scour, or sloughing of an embankment of bluff; also the stone so used. The quarrystone is placed in a layer that is at least twice the thickness of the 50 percent size or 1.25 times the thickness of the largest size stone in the gradation.
Risk curve groepsrisico-curve
Rubble Breuksteen, puin, stortsteen (1) Loose angular water worn stones along a beach. (2) Rough, irregular fragments of broken rock. See also RUBBLE MOUND
Rubble mound Breuksteen golfbreker A mound of random-shaped and random-placed stones protected with a cover layer of selected stones or specially shaped concrete armor units. (Armor units in a primary cover layer may be placed in an orderly manner or dumped at random.)
run-down golfterugloop
run-up golfoploop The rush of water up a structure or beach on the breaking of a wave. Also UPRUSH, SWASH. The amount of runup is the vertical height above still-water level to which the rush of water reaches.
Safety assessment toetsing
Safety standard veiligheidsnorm
Saltmarsh kwelder An area periodically flooded by water, usually above normal high water
Sand boil wel
saturated verzadigd
scour ontgronding, uitschuring Removal of underwater material by waves and currents, especially at the base or toe of a shore structure.
Sea state Description of the sea surface with regard to wave action. Also called state of sea.
Seas Zeegang Waves caused by wind at the place and time of observation.
Seawall Strandmuur A structure separating land and water areas and primarily designed to prevent erosion and other damage due to wave action. See also BULKHEAD.
Seepage kwel
Seepage screen kwelscherm screen (usually a sheetpile) under the construction that makes the seepage length longer
Seepage surface lekvlak
Seepange length kwellengte distance thw water has to travel through the soil body to leave at the landward side of a protection structure
segregation ontmenging
Seiche Seiche (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 that has the same frequency as the natural frequency of the fluid system. Tides are now considered to be seiches that are 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).
Semidiurnal tide Dubbeldaags getij A tide with two high waters and two low waters in a tidal day with comparatively little diurnal inequality.
settlement zetten (van grond)
Settlement zetting Vertical changes in the thickness of a soil layer due a load on top of this layer
Setup Opwaaiing See WIND SETUP or WAVE SETUP
Shallow Ondiep water 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.
shear stress schuifspanning
sheet pile damwand
Shingle Grind, kiezel (1) Loosely and commonly, any beach material coarser than ordinary gravel, especially any having flat or almost flat pebbles. (2) Strictly and accurately, beach material of smooth, well-rounded pebbles that are roughly the same size (fine 20 mm - coarse 60 mm). The spaces between pebbles are not filled with finer materials. Shingle often gives out a musical sound when stepped on.
Shoal Ondiepte A detached elevation of the sea bottom comprised of any material except rock or coral, which may endanger surface navigation.
Shoal Verondiepen (1) To become shallow gradually. (2) To cause to become shallow. (3) To proceed from a greater to a lesser depth of water. See also MIDDLE GROUND SHOAL. See also SHOALING COEFFICIENT
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.
Significant wave Significante golf A statistical term relating to the one-third highest waves of a given wave group and defined by the average of their heights and periods. The composition of the higher waves depends upon the extent to which the lower waves are considered. Experience indicates that a careful observer who attempts to establish the character of the higher waves will record values that approximately fit the definition of the significant wave.¶ The significant wave height is the average height of the one-third highest waves of a given wave group. Note that the composition of the highest waves depends upon the extent to which the lower waves are considered. In wave record analysis, the average height of the highest one-third of a selected number of waves, this number being determined by dividing the time of record by the significant period. Also CHARACTERISTIC WAVE HEIGHT. ¶ The significant wave period is an arbitrary period generally taken as the period of the one-third highest waves within a given group. Note that the composition of the highest waves depends upon the extent to which the lower waves are considered. In wave record analysis, this is defined as the average period of the most frequently recurring larger well-defined waves in the record under study.
sill drempel Shallow area in a gap, usually created as a foundation for a dam or an other structure
Slack water Kentering 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 intermediate period between ebb and flood currents during which the velocity of the currents is less than 0.05 meter per second (0.1 knot).
slags slakken
slide afschuiving sliding of a part of a ground body (usually with slope) because of exceedance of the internal shear strength
Slip circle glijcirkel
Slip surface glijvlak
Slope Helling The degree of inclination to the horizontal. Usually expressed as a ratio, such as 1:25 or 1 on 25, indicating 1 unit vertical rise in 25 units of horizontal distance; or in a decimal fraction (0.04); degrees (20°18'); or percent (4 percent).
sluice caisson doorlaatcaisson concrete caisson including weirs for closing works, these caissons prevent flow contraction during closing operation
Societal risk groepsrisico
Soil nailing Grondvernageling
Solitary wave Eenlinggolf A wave consisting of a single elevation (above the original water surface), whose height is not necessarily small compared to the depth and that is neither followed nor preceded by another elevation or depression of the water surfaces.
Sounding Dieptemeting A measured depth of water. On hydrographic charts, the soundings are adjusted to a specific plane of reference, the sounding datum. See also SOUNDING LINE
Sounding line Loodlijn A line, wire, or cord used in sounding, which is weighted at one end with a plummet (sounding lead). Also called LEAD LINE.
spill morsen
Spilling Spilling breakers -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 occurs over quite a distance.
Spit Spit A small point of land or a narrow shoal projecting into a body of water from the shore.
split-barge splijtbak
spread foundation staal (fundering op ..) a foundation without piles
spring tide springtij extreme high tide occurring once every two weeks
spur-dike krib, scherm
Stability stabiliteit
stacking up willow mattresses opzinken making a closure dam by sinking subsequent willow mattresses on top of each other
Standing wave Staande golf A 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 travelling through each other in opposite directions. Sometimes called CLAPOTIS or STATIONARY WAVE.
Stern achtersteven, hek
Stochastic variable stochast a variable with a certain stochastic variation
Stockpile Voorraad Sand piled on a beach foreshore to nourish downdrift beaches by natural littoral currents or forces. See FEEDER BEACH.
stoplog schotbalk beam temporary placed in e.g. a lock to make a temporary closure (in case of maintenance or emergency)
Storm surge Opwaaiing, windopzet A rise above normal water level on the open coast due to the action of wind stress on the water surface. Storm surge resulting from a hurricane also includes that rise in level due to atmospheric pressure reduction as well as that due to wind stress. See WIND SETUP.
Stream line stroomlijn
submerged weir, imperfect weir, submerged overfall Onvolkomen overlaat
Subsoil ondergrond
Suffusion Uitlogingserosie migration of soil particles through the soil matrix
Surf Branding The wave activity in the area between the shoreline and the outermost limit of breakers. Se also SURF BEAT and SURF ZONE
Surf beat Irregular oscillations of the nearshore water level with periods on the order of several minutes.
Surf Similarity parameter Iribarrengetal dimensionless parameter to descibe wave-structure interaction, the ratio between structur slope and wave steepness
Surf zone Brandingszone The area between the outermost breaker and the limit of wave uprush.
surge deinen 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 low in height, usually less than 0.9 meter (0.3 foot). See also SEICHE.
surge stormopzet
Surging Surging breakers - 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 beach face during runback.
Swell Deining Wind-generated waves that have traveled out of their generating area. Swell characteristically exhibits a more regular and longer period and has flatter crests than waves within their fetch (SEAS).
SWL stil water niveau Still Water level, the elevation that the surface of the water would assume if all wave action were absent.
Synoptic synoptisch Synoptic chart, a chart showing the distribution of meteorological conditions over a given area at a given time. Popularly called a weather map.
tailwater benedenwater
threshold drempel
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. Also called lunar day.
Tidal flat Bank, slik, schor Marshy or muddy land areas which are covered and uncovered by the rise and fall of the tide.
tidal flat closure maaiveldsluiting closing a tidal entrance by closing the shallow parts on the tidal flats
tidal gully closure stroomgat sluiting closing a tidal entrance by closing the gully as last closing part
Tidal prism Getijprisma 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 range Tijverschil The difference in height between consecutive high and low (or higher high and lower low) waters.
Tidal rise The height of tide as referred to the datum of a chart.
Tidal wave Getijgolf (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 sometimes erroneously to TSUNAMI).
Tide getijprisma The periodic rising and falling of the water that results from gravitational attraction of the Moon and Sun and other astronomical bodies acting upon the rotating Earth. Although the accompanying 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 vertical movement. See also SPRING TIDE, NEAP TIDE, MIXED TIDE; see also TIDAL DAY, TIDAL FLAT, TIDAL PRISM, TIDAL RANGE, TIDAL RISE, TIDAL WAVE, TIDE STATION
Tide station Getijstation 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 that is operated over a short period of time to obtain data for a specific purpose.
Toe teen
Toe ditch kwelsloot A ditch at the inner side of a dike to catch the seepage water and discharge it
Total stress totaalspanning
Translation wave Translatiegolven A wave in which the water particles are permanently displaced to a significant degree in the direction of wave travel. Distinguished from an OSCILLATORY WAVE.
Transmissivity doorlatendheid
Trochoidal wave Trochoïdale golf A theoretical, progressive oscillatory wave first proposed by Gerstner in 1802 to describe the surface profile and particle orbits of finite amplitude, non-sinusoidal waves. The waveform 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. Compare IRROTATIONAL WAVE
Trough Golfdal Trough of a wave, the lowest part of a waveform between successive crests. Also, that part of a wave below still-water level.
Tsunami Tsunami A long-period wave caused by an underwater disturbance such as a -volcanic eruption or earthquake. Also SEISMIC SEA WAVE. Commonly miscalled "tidal wave."
tug sleepboot
Uplift Opwaartse druk The upward water pressure on the base of a structure or pavement.
Uprush omhoog stromen in golfoploop The rush of water up onto the beach following the breaking of a wave. Also SWASH, RUNUP.
Variability Vartiability of waves(1) The variation of heights and periods between 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 generating area. (3) The variation in height along the crest, usually called "variation along the wave."
Viscosity Viscositeit That molecular property of a fluid that enables it to support tangential stresses for a finite time and thus to resist deformation.
voids poriën
Volumetric weight volumegewicht
vortex, eddy neer, wervel A circular movement of water formed on the side of a main current. Eddies may be created at points where the main stream passes projecting obstructions or where two adjacent currents flow counter to each other. Also EDDY CURRENT.
wake zog (van schip)
Water board waterschap
water-borne vanaf het water (lett. door het water gedragen)
Wave Golf See also: Edge wave, gravity wave, monochromatic wave, progressive wave, reflected wave, solitary wave, standing wave, translation wave, trochoidal wave, wave celerity, wave forecasting, wave generation, wave group, wave height, wave period, wave propagation, wave setupwave spectrum, wave of translation, wave trough, wave velocity and wavelength
Wave celerity Golfsnelheid speed at which an individual wave advances
Wave generation Golfopwekking (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.
Wave group Golfgoep A series of waves in which the wave direction, wavelength, and wave height vary only slightly. See also GROUP VELOCITY.
Wave height Golfhoogte The vertical distance between a crest and the preceding trough. See also SIGNIFICANT WAVE HEIGHT.
Wave period Golfperiode The time for a wave crest to traverse a distance equal to one wavelength. The time needed for two successive wave crests to pass a fixed point. See also SIGNIFICANT WAVE PERIOD.
Wave propagation Golfvoortplanting The transmission of waves through water.
Wave setup Golfopzet Super-elevation of the water surface over normal surge elevation due to onshore mass transport of the water by wave action alone.
Wave spectrum Golfspectrum In ocean wave studies, a graph, table, or mathematical equation showing the distribution of wave energy as a function of wave frequency. The spectrum may be based on observations or theoretical considerations. Several forms of graphical display are widely used.
Wave trough Golfdal The lowest part of a wave form between successive crests. Also that part of a wave below still-water level.
Wave velocity Golfsnelheid The speed at which an individual wave advances, usually called wave celerity
Wavelength Golflengte The horizontal distance between similar points on two successive waves measured perpendicular to the crest.
well wel a place where groundwater is upwelling
wind set up (storm surge) windopzet (opwaaing) local rise of the waterlevel due to the wind action)
Wind waves Windgolven (1) Waves formed and built up by the wind. (2) Loosely, any wave generated by wind.
Windward The direction from which the wind is blowing.