Observations of Waves and Currents Near the Surf Zone

1999 ◽  
Author(s):  
Jerome A. Smith
Keyword(s):  
Surf Zone ◽  
Waves And Currents

scholarly journals THE NEARSHORE SEDIMENT TRANSPORT STUDY

1978 ◽  
Vol 1 (16) ◽  
pp. 92 ◽  
Author(s):  
Richard J. Seymour ◽  
David B. Duane
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Surf Zone ◽  
Coastal Engineering ◽  
Predictive Tools ◽  
Transport Study ◽  
Sediment Size ◽  
Forcing Function ◽  
Nearshore Sediment Transport ◽  
Waves And Currents

The models for predicting longshore transport of sediment along straight coastlines that are presently in general use were derived empirically from very sparse measurements of both the forcing function (waves and currents) and the response function (sediment motions). A detailed treatment of these data sets is contained in Greer and Madsen (1978). In addition to the generally unsatisfactory nature of the basic measurements upon which they were based, the models may be deficient because they fail to employ such potentially significant factors as wind stress, sediment size distribution, bottom slope and spatial variations in waves and currents, including the effects of rip currents. Although these models have served certain engineering needs, there is a strong measure of uncertainty in the coastal engineering community about their general applicability. Certainly, because they are empirical rather than physically reasoned models, there is no rational means for extending their usefulness to predicting transport where coastlines are not straight -- such as the case of a tidal inlet. The economic impact of sediment transport in the nearshore regime is enormous and the need for improved predictive tools appears to be universally accepted. To be most useful, these improved models must be globally applicable. This implies very strongly that they must be based upon a thorough understanding of surf zone dynamics and the details of the response of the sediment. The surf zone flow fields are highly complex and nonlinear, implying an equally complex and difficult system of sediment responses. Characterizing the entire forcing and response functions simultaneously requires large and expensive field measurement programs that greatly exceed the present state of the art of measurement and analysis.' The approach of the last two decades of single investigators working at laboratory scale or in the ocean with a few single point measurements would not appear to ever meet these needs. However, the present costs for coastal dredging and shoreline protection, which can be measured in billions of dollars on a world scale, argue for a major undertaking to develop better predictive tools. In an attempt to satisfy these needs, an ad hoc group was formed at the Fifteenth Coastal Engineering Conference in Honolulu to plan a large scale and coordinated series of investigations leading to improved sediment transport predictive models. Less than a year later, the Nearshore Sediment Transport Study was initiated under the sponsorship of the Office of Sea Grant.

scholarly journals THE INTERACTION OF WAVES AND CURRENTS OVER A LONGSHORE BAR

1986 ◽  
Vol 1 (20) ◽  
pp. 116 ◽  
Author(s):  
I.A. Svendsen ◽  
J. Buhr Hansen
Keyword(s):  
Wave Height ◽  
Wave Motion ◽  
Surf Zone ◽  
Wave Theory ◽  
Runge Kutta Method ◽  
Waves And Currents ◽  
Set Up ◽  
The Waves ◽  
Wave Properties ◽  
A Current

A two-dimensional model for waves and steady currents in the surf zone is developed. It is based on a depth integrated and time averaged version of the equations for the conservation of mass, momentum, and wave energy. A numerical solution is described based on a fourth order Runge-Kutta method. The solution yields the variation of wave height, set-up, and current in the surf zone, taking into account the mass flux in the waves. In its general form any wave theory can be used for the wave properties. Specific results are given using the description for surf zone waves suggested by Svendsen (1984a), and in this form the model is used for the wave motion with a current on a beach with a longshore bar. Results for wave height and set-up are compared with measurements by Hansen & Svendsen (1986).

scholarly journals Sediment Transport Beyond the Surf Zone Under Waves and Currents of the Non-Tidal Sea: Lubiatowo (Poland) Case Study

2016 ◽  
Vol 63 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Rafał Ostrowski ◽  
Magdalena Stella
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Coastal Region ◽  
Wave Climate ◽  
Soil Parameters ◽  
Shear Stresses ◽  
Research Station ◽  
Sea Bed ◽  
Waves And Currents ◽  
Bed Changes

Abstract The paper deals with the sandy coastal zone at Lubiatowo in Poland (the south Baltic Sea). The study comprises experimental and theoretical investigations of hydrodynamic and lithodynamic processes in the coastal region located close to the seaward boundary of the surf zone and beyond the surf zone. The analysis is based on field data collected at the IBW PAN Coastal Research Station in Lubiatowo. The data consist of wind velocity reconstructed from the long-term wave climate, deep-water wave buoy records and sea bottom soil parameters. Nearbed flow velocities induced by waves and currents, as well as bed shear stresses are theoretically modelled for various conditions to determine sediment motion regimes in the considered area. The paper discusses the possibility of occasional intensive sediment transport and the occurrence of distinct sea bed changes at bigger water depths.

scholarly journals SHORE-PARALLEL FLOWS IN A BARRED NEARSHORE

1982 ◽  
Vol 1 (18) ◽  
pp. 101
Author(s):  
Brian Greenwood ◽  
Douglas J. Sherman
Keyword(s):  
Vertical Structure ◽  
Roughness Length ◽  
Surf Zone ◽  
Parameter Estimate ◽  
Velocity Profiles ◽  
Electromagnetic Current ◽  
Data Smoothing ◽  
Parallel Flows ◽  
Mixing Parameter ◽  
Waves And Currents

A field experiment to measure the horizontal and vertical structure of shore-parallel, nearshore currents was conducted at Wendake Beach, Georgian Bay, Canada, in 1980. Waves and currents were measured with continuous resistance wire wave staffs and bi-directional, electromagnetic current meters, respectively. Substantial variations from theoretical horizontal velocity profiles were found as an influence of small amplitude nearshore bars. Data smoothing resulted in a Longuet- Higgins type mixing parameter estimate of P=0.18. Vertical velocity profiles analysis suggests that an estimate of mean, surf zone roughness length is of the order of lxl0-3m.

scholarly journals FIELD MEASUREMENTS OF SAND MOTION IN THE SURF ZONE

1980 ◽  
Vol 1 (17) ◽  
pp. 73 ◽  
Author(s):  
Douglas L. Inman ◽  
James A. Zampol ◽  
Thomas E. White ◽  
Daniel M. Hanes ◽  
B. Walton Waldorf ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Surf Zone ◽  
Field Measurements ◽  
Suspended Load ◽  
Bed Load ◽  
Simultaneous Measurements ◽  
Longshore Transport ◽  
Waves And Currents ◽  
Measured Load ◽  
Rigorous Method

Forcing functions and sediment response were measured during two comprehensive surf zone experiments. The experiments included simultaneous measurements of waves and currents, and the movement of sediment as bed and suspended load. The longshore transport of suspended load was found to be about 10 to 20% of the tracer-measured load. Results from tracer measurements of the longshore transport of bed load indicate that previous measurements may have misestimated the effective "tracer layer thickness," and a more rigorous method is proposed.

scholarly journals Mathematical modelling of the propagation of accidental oil spills when designing an artificial beach in Svetlogorsk, Kaliningrad region

2020 ◽  
Vol 224 ◽  
pp. 01044
Author(s):  
K.N. Makarov ◽  
I.L. Makarova
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Modelling ◽  
Surf Zone ◽  
Oil Spills ◽  
Oil Pollution ◽  
Point Of View ◽  
Shallow Sea ◽  
Research Results ◽  
Waves And Currents ◽  
Kaliningrad Region

The article deals with the issues of mathematical modeling of the transformation and drift of an oil product spill in case of possible ship accidents both in the shallow sea zone at depths of 25-30 m, and in the surf zone at depths of 3-5 m. The method for modeling the drift of an oil product slick under the influence of waves and currents is presented. The most dangerous hydro-meteorological situations from the point of view of liquidation of the consequences of accidents are considered and the simulation of the drift of oil pollution is carried out. The research results make it possible to develop optimal plans for the elimination of oil spills.

scholarly journals Intertidal finger bars at El Puntal, Bay of Santander, Spain: observation and forcing analysis

2014 ◽  
Vol 2 (1) ◽  
pp. 349-361 ◽  
Author(s):  
E. Pellón ◽  
R. Garnier ◽  
R. Medina
Keyword(s):  
Surf Zone ◽  
High Tide ◽  
Small Scale ◽  
Sand Transport ◽  
Maximum Speed ◽  
Northern Coast ◽  
Astronomical Tide ◽  
Transport Direction ◽  
Waves And Currents ◽  
Main Candidate

Abstract. A system of 15 small-scale finger bars has been observed, by using video imagery, between 23 June 2008 and 2 June 2010. The bar system is located in the intertidal zone of the swell-protected beaches of El Puntal Spit, in the Bay of Santander (northern coast of Spain). The bars appear on a planar beach (slope = 0.015) with fine, uniform sand (D50 = 0.27 mm) and extend 600 m alongshore. The cross-shore span of the bars is determined by the tidal horizontal excursion (between 70 and 130 m). They have an oblique orientation with respect to the low-tide shoreline; specifically, they are down-current-oriented with respect to the dominant sand transport computed (mean angle of 26° from the shore normal). Their mean wavelength is 26 m and their amplitude varies between 10 and 20 cm. The full system slowly migrates to the east (sand transport direction) with a mean speed of 0.06 m day-1, a maximum speed in winter (up to 0.15 m day-1) and a minimum speed in summer. An episode of merging has been identified as bars with larger wavelength seem to migrate more slowly than shorter bars. The wind blows predominantly from the west, generating waves that transport sediment across the bars during high-tide periods. This is the main candidate to explain the eastward migration of the system. In particular, the wind can generate waves of up to 20 cm (root-mean-squared wave height) over a fetch that can reach 4.5 km at high tide. The astronomical tide seems to be important in the bar dynamics, as the tidal level changes the fetch and also determines the time of exposure of the bars to the surf-zone waves and currents. Furthermore, the river discharge could act as input of suspended sediment in the bar system and play a role in the bar dynamics.

scholarly journals Three-dimensional modelling of wave-induced current from the surf zone to the inner shelf

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 657-681 ◽  
Author(s):  
H. Michaud ◽  
P. Marsaleix ◽  
Y. Leredde ◽  
C. Estournel ◽  
F. Bourrin ◽  
...  
Keyword(s):  
Surf Zone ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Circulation Model ◽  
Good Representation ◽  
Depth Range ◽  
Littoral Drift ◽  
Inner Shelf ◽  
Waves And Currents ◽  
The Impact

Abstract. We develop and implement a new method to take into account the impact of waves into the 3-D circulation model SYMPHONIE (Marsaleix et al., 2008, 2009a) following the simplified equations of Bennis et al. (2011) which use glm2z-RANS theory (Ardhuin et al., 2008c). These adiabatic equations are completed by additional parameterizations of wave breaking, bottom friction and wave-enhanced vertical mixing, making the forcing valid from the surf zone through to the open ocean. The wave forcing is performed by wave generation and propagation models WAVEWATCH III® (Tolman, 2008, 2009; Ardhuin et al., 2010) and SWAN (Booij et al., 1999). The model is tested and compared with other models for a plane beach test case, previously tested by Haas and Warner (2009)and Uchiyama et al. (2010). A comparison is also made with the laboratory measurements of Haller et al. (2002) of a barred beach with channels. Results fit with previous simulations performed by other models and with available observational data. Finally, a realistic case is simulated with energetic waves travelling over a coast of the Gulf of Lion (in the northwest of the Mediterranean Sea) for which currents are available at different depths as well as an accurate bathymetric database of the 0–10 m depth range. A grid nesting approach is used to account for the different forcings acting at different spatial scales. The simulation coupling the effects of waves and currents is successful to reproduce the powerful northward littoral drift in the 0–15 m depth zone. More precisely, two distinct cases are identified: When waves have a normal angle of incidence with the coast, they are responsible for complex circulation cells and rip currents in the surf zone, and when they travel obliquely, they generate a northward littoral drift. These features are more complicated than in the test cases, due to the complex bathymetry and the consideration of wind and non-stationary processes. Wave impacts in the inner shelf are less visible since wind and regional circulation seem to be the predominant forcings. Besides, a discrepancy between model and observations is noted at that scale, possibly linked to an underestimation of the wind stress. This three-dimensional method allows a good representation of vertical current profiles and permits the calculation of the shear stress associated with waves and currents. Future work will focus on the combination with a sediment transport model.

scholarly journals MODELLING INFRAGRAVITY WAVES AND CURRENTS ACROSS A FRINGING CORAL REEF

2012 ◽  
Vol 1 (33) ◽  
pp. 29 ◽  
Author(s):  
Ap Van Dongeren ◽  
Ryan Lowe ◽  
Andrew Pomeroy ◽  
Trang Minh Duong ◽  
Dano Roelvink ◽  
...  
Keyword(s):  
Coral Reef ◽  
Surf Zone ◽  
Low Frequency ◽  
Infragravity Waves ◽  
Wave Dynamics ◽  
Short Waves ◽  
Model Study ◽  
Waves And Currents ◽  
The One ◽  
Water Level Measurements

Low-frequency (infragravity) wave dynamics on a fringing coral reef were investigated using the numerical model XBeach (Roelvink et al, 2009). First, the skill of the one-dimensional model was evaluated based on its predictions of short waves (0.04-0.2 Hz), infragravity waves (0.004-0.04 Hz) and water level measurements (tidal and wave setup) obtained during a 2009 field study at Ningaloo Reef in Western Australia. The model calibration was sensitive to friction coefficients for short waves and current / infragravity bed friction, which were assumed independent in this model study. The infragravity waves were found to be generated primarily in the surf zone through the breakpoint generation mechanism rather than through offshore forcing. The infragravity waves were strongly also modulated over the reef by tidal depth variations, primarily due to the variability in frictional dissipation rates when the total water depth over the reef varied. The results reveal that short waves dominated bottom stresses on the fore reef and near the reef crest; however, inside the lagoon, infragravity waves become increasingly dominant, accounting up to 50% of the combined bottom stresses

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