Effects Of Tidal Currents Research Articles

The effect of evaporation on the erodibility of mudflats in a mesotidal estuary

Large areas of mesotidal estuaries become subaerial during low tide. Here we study the effect of several meteorological and hydrodynamic parameters on the erodibility of mudflat substrates when they are subaerial. Field measurements carried out over a two-week period in September 2011 in Plum Island Sound, Massachusetts USA, indicate that high evaporation rates and long subaerial periods are associated to low sediment erodibility. Sediment concentrations in the water column during submergence depend on bottom shear stresses triggered by tidal currents. Surprisingly, they are also related to the total evaporation that occurred in the previous emergence period. We conclude that low erodibility of mudflat sediments is linked to subaerial desiccation at low tide. This strengthening effect is not lost during the following submerged period, thus limiting the erosive effect of tidal currents. We thus show that not only subaqueous but also subaerial processes might control the erodibility of mudflats. Long-term evaporation rates can therefore directly affect the stability of mudflats in mesotidal environments.

Modelling effects of tidal currents on waves at a tidal stream energy site

Whereas tidal stream energy sites may be characterised by significant wave and current interactions, numerical resource assessments routinely ignored these processes neglecting, in particular, current-induced modifications of waves. Here, these effects are investigated in locations exposed to ocean waves, evaluating performances of a phase-averaged numerical wave model to approach observed semi-diurnal modulations of wave heights, periods and directions, off and within the Fromveur Strait (western Brittany), a region with strong potential for tidal array development. The introduction of tidal forcings in the wave model is found to improve predictions by approaching the large-scale influence of current-induced refraction leading to variations of the significant wave height by nearly 30% at the deep-water wave buoy. The model reproduces furthermore, with the inclusion of an additional dissipation term, the localised steepening and waves breaking on negative current gradients, limiting the overestimation of the significant wave height at the shallow-water wave buoy within the Fromveur Strait. Tidal currents may finally lead to a strong increase in wave power, over 100% in northern entrances of straits, contributing to the variability of the wave energy flux.

Modelling wave–current interactions off the east coast of Scotland

Abstract. Densely populated coastal areas of the North Sea are particularly vulnerable to severe wave conditions, which overtop or damage sea defences leading to dangerous flooding. Around the shallow southern North Sea, where the coastal margin is lying low and population density is high, oceanographic modelling has helped to develop forecasting systems to predict flood risk. However, coastal areas of the deeper northern North Sea are also subject to regular storm damage, but there has been little or no effort to develop coastal wave models for these waters. Here, we present a high spatial resolution model of northeast Scottish coastal waters, simulating waves and the effect of tidal currents on wave propagation, driven by global ocean tides, far-field wave conditions, and local air pressure and wind stress. We show that the wave–current interactions and wave–wave interactions are particularly important for simulating the wave conditions close to the coast at various locations. The model can simulate the extreme conditions experienced when high (spring) tides are combined with sea-level surges and large Atlantic swell. Such a combination of extremes represents a high risk for damaging conditions along the Scottish coast.

Coastal tomographic mapping of nonlinear tidal currents and residual currents

Depth-averaged current data, which were obtained by coastal acoustic tomography (CAT) July 12–13, 2009 in Zhitouyang Bay on the western side of the East China Sea, are used to estimate the semidiurnal tidal current (M2) as well as its first two overtide currents (M4 and M6). Spatial mean amplitude ratios M2:M4:M6 in the bay are 1.00:0.15:0.11. The shallow-water equations are used to analyze the generation mechanisms of M4 and M6. In the deep area, where water depths are larger than 60m, M4 velocity amplitudes measured by CAT agree well with those predicted by the advection terms in the shallow water equations, indicating that M4 in the deep area is predominantly generated by the advection terms. M6 measured by CAT and M6 predicted by the nonlinear quadratic bottom friction terms agree well in the area where water depths are less than 20m, indicating that friction mechanisms are predominant for generating M6 in the shallow area. In addition, dynamic analysis of the residual currents using the tidally averaged momentum equation shows that spatial mean values of the horizontal pressure gradient due to residual sea level and of the advection of residual currents together contribute about 75% of the spatial mean values of the advection by the tidal currents, indicating that residual currents in this bay are induced mainly by the nonlinear effects of tidal currents. This is the first ever nonlinear tidal current study by CAT.

A simplified method to estimate tidal current effects on the ocean wave power resource

Although ocean wave power can be significantly modified by tidal currents, resource assessments at wave energy sites generally ignore this effect, mainly due to the difficulties and high computational cost of developing coupled wave-tide models. Furthermore, validating the prediction of wave-current interaction effects in a coupled model is a challenging task, due to the paucity of observational data. Here, as an alternative to fully coupled numerical models, we present a simplified analytical method, based on linear wave theory, to estimate the influence of tidal currents on the wave power resource. The method estimates the resulting increase (or decrease) in wave height and wavelength for opposing (or following) currents, as well as quantifying the change in wave power. The method is validated by applying it to two energetic locations around the UK shelf – Pentland Firth and Bristol Channel – where wave/current interactions are significant, and for which field data are available. Results demonstrate a good accuracy of the simplified analytical approach, which can thus be used as an efficient tool for making rapid estimates of tidal effects on the wave power resource. Additionally, the method can be used to help better interpret numerical model results, as well as observational data.

Statistical characterization of spatiotemporal sediment dynamics in the Venice lagoon

AbstractCharacterizing the dynamics of suspended sediment is crucial when investigating the long‐term evolution of tidal landscapes. Here we apply a widely tested mathematical model which describes the dynamics of cohesive and noncohesive sediments, driven by the combined effect of tidal currents and wind waves, using 1 year long time series of observed water levels and wind data from the Venice lagoon. The spatiotemporal evolution of the computed suspended sediment concentration (SSC) is analyzed on the basis of the “peak over threshold” theory. Our analysis suggests that events characterized by high SSC can be modeled as a marked Poisson process over most of the lagoon. The interarrival time between two consecutive over threshold events, the intensity of peak excesses, and the duration are found to be exponentially distributed random variables over most of tidal flats. Our study suggests that intensity and duration of over threshold events are temporally correlated, while almost no correlation exists between interarrival times and both durations and intensities. The benthic vegetation colonizing the central southern part of the Venice lagoon is found to exert a crucial role on sediment dynamics: vegetation locally decreases the frequency of significant resuspension events by affecting spatiotemporal patterns of SSCs also in adjacent areas. Spatial patterns of the mean interarrival of over threshold SSC events are found to be less heterogeneous than the corresponding patterns of mean interarrivals of over threshold bottom shear stress events because of the role of advection/dispersion processes in mixing suspended sediments within the lagoon. Implications for long‐term morphodynamic modeling of tidal environments are discussed.

New procedure for the analysis of speed trial results, with special attention to the correction of tidal current effect

Almost all the existing analysis methods of speed trial results were proposed before 1970s, and the actual analysis procedures are very old-fashioned with instructions like “plot the results on a chart and draw a smooth mean line”, “read a value from the mean line” and so on. Such instructions not only show up the analysis procedures old-fashioned, but also make them very ambiguous and unclear. They should be up-dated to a method which is clear not only in logic but also in calculation procedure, and also fits the present computing technology. At first, the author reviewed the major analysis methods and concluded that the logic of the up-dated analysis procedure can be composed of the logics of the existing ones. Then, the analysis procedure is composed of three stages; namely (1) correction of power and propeller revolution to the ones corresponding to no air condition, (2) correction of tidal current effect, and (3) correction of power and propeller revolution to the ones corresponding to no wind condition. For the stages (1) and (3), there seems to be no big issue except the estimation of the amount of environmentally added resistance in the stage (1). Then, the author focused on the correction of tidal current effect in this paper. For the correction of tidal current effect, the author considers the essential points for the up-date are in the direction of finding out appropriate functions for the variation of tidal current velocity and the ship speed through the water. Then, he investigated to find out such functions and made his proposal. Finally, the applicability of the new procedure is assessed by the analysis of simulated speed trial results of a VLCC.

Deep-water sedimentary systems and their relationship with bottom currents at the intersection of Xisha Trough and Northwest Sub-Basin, South China Sea

Based upon 2D reflection seismic data and numerical modelling, this study confirms the presence of a complex deep-water sedimentary system on the present-day seafloor at the intersection of the Xisha Trough and the Northwest Sub-Basin (South China Sea) and investigates their relationship with bottom currents. The deep-water sedimentary system consists of submarine canyons, slides and slumps, wave-like successions, mounded drifts and two groups of marginal depressions (those with erosional features and those appearing as morphological sediment sinks). Three-dimensional process-based modelling is applied to investigate sediment dynamics induced by a combined effect of tidal currents and a quasi-steady geostrophic current (South China Sea Deep Water Circulation). Simulation results show that the South China Sea Deep Water Circulation at the southeastern flank of the seamount plateau could reach velocities of 15cm/s during flood tides, enabling erosion and transport processes. In contrast, the rest of the plateau area is favoured for deposition, since current velocities in this region are persistently lower than 10cm/s. The current velocities at the feet of the obstacles (where the morphological depressions are located) are strengthened and are several cm/s higher than that in adjacent flat areas (e.g. where the mounded drifts are located). The flow is constricted and accelerated after being deflected by the obstacles, resulting in contrasting higher sedimentation rates within the mounded sediments and lower rates at the morphological depressions. A comparison between the seismic stratigraphy and the simulated fluid dynamics enables a decoding of the pathway, identifying the current regime as well as unravelling the relationship between depositional processes and the deep-sea water circulation. This study provides new insights and exposes new challenges in understanding the dynamics of deep-sea sedimentation processes in South China Sea.

Effect of simulated tidal currents on the burrow emergence rhythms of the Norway lobster (Nephrops norvegicus)

Light is the most important zeitgeber for the synchronization of biological rhythms in terrestrial organisms. In the sea, the light intensity progressively decreases, and tidal currents might control behavioural rhythms at disphotic depths. The Norway lobster, Nephrops norvegicus, is distributed from the upper shelf to middle slope areas. Its burrowing behaviour is under the control of a circadian system, and the effects of tidal currents have been inferred from catchability patterns. Male lobsters were collected from 100 m depth off the Ebro Delta, Tarragona, Spain (40° 39′N, 1° 13′E). Light intensity and water current cycles were simulated in the laboratory to investigate their combined effects on burrow emergence behavioural rhythms (June–July 2012). Periodic water currents (10 cm s−1) inhibited N. norvegicus burrow emergence to a degree dependent on the relative phase between light and water current cycles. The lobsters preferred to remain inside the burrow in the presence of water currents. However, when they were outside the burrow, they spent more time orientated downstream during darkness hours. Moreover, four of the 15 lobsters showed that a current could act as a putative zeitgeber for the circadian oscillator, but further experiments are needed to confirm this finding. These results indicate that tidal current is an important parameter to consider when interpreting fishery-dependent data and data from video surveys, not only N. norvegicus, but for other deep-water epibenthic species.

Sediment dynamics in a complex coastal lagoon system of the Gulf of California

Intense transport of sediments occurs along the eastern coast of the Gulf of California, interacting with several coastal lagoons like Santa Maria-La Reforma. This sediment dynamics plays an important role in the conservation issue of marine species. The effect of tidal currents on the bed load sediment transport has been investigated for this lagoon, emphasizing the mechanisms of the geomorphologic development of the sea bottom. The flow dynamics has been studied applying the vertically integrated shallow water equations through a modified two dimensional non-linear finite difference model. A parameterized formula for the bed load sediment transport and a sediment conservation equation were applied to investigate the morphodynamics of the sea bottom of the lagoon. The predicted currents pattern allowed identifying a zone where tidal waves, entering into the lagoon throughout the northern and southern openings, meet. This process had consequences on the bed load transport of sediment. The results revealed areas where the currents induce noticeable erosion and accretion processes. The complex geometry of the lagoon seems to determine the accretion and erosion areas. Important changes of the order of 0.04 m per year were predicted nearby the Northern inlet and around the Talchichitle Island. The lagoon system exports sediment through the two inlets. This research work contributes to the understanding of the sediment dynamics in an extensive region with a series of coastal lagoons located on the eastern side of the Gulf of California.

Modeling sorting dynamics of cohesive and non-cohesive sediments on intertidal flats under the effect of tides and wind waves

We extend a numerical model to explore the morphodynamics of intertidal flats, with a specific focus on the sorting dynamics of sand and mud. We investigate the effect of tidal currents, wind waves, sediment properties, external sediment supply, flocculation and initial bed composition on the cross-shore profile shape and sediment sorting of intertidal flats. Consistent with existing analytical theories and benchmark simplified numerical solutions, the equilibrium cross-shore profile of intertidal flats simulated by the extended model is convex-up when tidal currents dominate and it progressively becomes concave-up when the strength of wind waves increases. The equilibrium profile is influenced by the external sediment supply which can lead to the seaward advance of intertidal flats. In line with field observations, mud tends to deposit on the upper intertidal flats when wind waves are relatively weak, while sand is mainly distributed on the middle and lower tidal flats. When wind waves are strong, both sand and mud are more easily resuspended and eroded, resulting in a noticeably concave-up profile near the high water mark. The initial bed composition (e.g., percentage of mud and sand fractions) is also found to play an important role: the intertidal flat is more convex-up in a muddier environment. Numerical modeling demonstrates that sediment properties (e.g., critical shear stress for erosion, settling velocity) and flocculation can pronouncedly influence the sediment sorting dynamics by modifying the initiation threshold and the advection distance of entrained sediments. Application of the extended model to a natural study site indicates a qualitative agreement with field observations.

TSUNAMI-TIDE INTERACTION IN THE SETO INLAND SEA, JAPAN

Tsunami-tide interactions in the Seto Inland Sea (SIS) were investigated by taking into account the effects of tidal currents on the tsunami propagation in terms of the arrival time and the run-up heights along the coast of SIS. The initial tsunami wave profile was introduced by the possible Tokai-Tonankai-Nankai Earthquake of the magnitude Mw9.0, which is equivalent to that of 2011 Tohoku Earthquake. Numerical experiments with four different tidal phases, flood, ebb, high, and low, reveal that the water depth changes due to tides affect the tsunami propagation in terms of heights and arrival time. During high tides, the tsunami propagates faster and reaches higher than during the low tides. In addition, during the flood tides with rising water level, tsunami propagates faster than during the ebb tides. Further investigation also shows that the tsunami-tide interaction changes the tsunami signal such that the tsunami-only spectra shifts the spectral peaks after considering the tsunami-tide interactions. Local oscillation modes characterized by local bathymetry and topography shift to higher frequency modes due to the non-linear tsunami-tide interaction. To reduce the uncertainties involved in tsunami predictions and coastal defenses and management, it is strongly recommended to simulate tsunamis together with tides in shallow water environments.

Sediment rarefaction resuspension and contaminant release under tidal curren- ts

Based on experiment in tidal flume, this paper analyzes the sediment rarefactive phenomenon and hydraulic characteristics of sediment resuspension with different physical properties under the effect of tidal current. According to this experiment, sediment resuspension is related to the hydraulic characteristics of overlying water and its own dry density, namely the moisture content of sediment and deposition time. Generally, river sediment can be classified into the upper layer of floating sludge and lower layer of deposit sediment. Incipient velocity goes higher as the sediment layer goes thicker. Based on the experiment, incipient velocity formula of sediment can be obtained. There is a cohesive force among natural fine sediment whose resuspension is almost irrelevant to their diameters. Therefore, the critical incipient velocity is determined by the cohesive force instead of particle diameter. The lower layer of deposit sediment is generally not so easy to start up. And it will be rarified and release into the overlying water when contacting with overlying water. However, this rarefaction release velocity is gentle and slow. Under the same flow condition, annual loss amount of lower layer deposited sediment is about one fifth of upper layer of floating sediment. Flow velocity of tidal river and variation of the water level are asymmetrical, both of which vary under different tidal cycles. During long tidal cycle, flow velocity and water level change in the same phase and amplitude with tide. During the whole ebb and flow, flow direction does not change as the water level goes under the influence of acceleration and deceleration. As the tide cycle increases, the incipient velocity of sediment goes higher. This means that the long period tide cycle plays buffer effect on the resuspension of sediment, which makes the sediment not so easy both to start up and to suspend.

THE INFLUENCE OF AQUACULTURE ON MODERN FORAMINIFERA AND SEDIMENTS IN THE SETIU ESTUARY AND LAGOON, TERENGGANU, MALAYSIA: A TEMPORAL INVESTIGATION

Foraminifera, grain size, and carbon and nitrogen isotope ratios and abundances were analyzed in surface-sediment samples collected from three floating fish-cage complexes to address how aquaculture has influenced the Setiu estuary and lagoon of northeast peninsular Malaysia. Two currently active floating fish-cage complexes, SET11-S43 and SET11-S40, are located in the semi-enclosed Setiu lagoon, within four km of an inlet connecting to the South China Sea. The sampling areas experience salinities in the 20s, and sediments have mixed agglutinated and calcareous foraminiferal [total] assemblages, generally dominated by Ammonia aff. A. aoteana and Ammobaculites exiguus . The majority of live foraminifera at these sites belong to agglutinated species; percent of live specimens is greater around the SET11-S43 fish-cage complex, likely related to the presence of aquaculture-related organic-rich mud. Percent agglutinated specimens in total assemblages (live + dead) decrease towards the inlet as total assemblage density and diversity increase due to increased salinity. At a recently (1–3 years) abandoned fish-cage complex, SET11-S9A, located in a low salinity (<5) estuarine setting, Miliammina fusca and Am. exiguus dominate total assemblages. Surface-sediment grain-size data indicate that fish-cage-related organic-rich mud underlies SET11-S43 and extends tens of meters to the north with a surrounding sandier substrate, typical of most of the Setiu estuary and lagoon system. SET11-S40 is underlain by generally sandy sediment; organic-rich mud characterizes the lagoon immediately to the north of this fish-cage complex. Percent carbon and nitrogen in sediment exhibit distributional patterns that strongly correlate with the distribution of fish-cage mud. Greater amounts of mud, carbon, and nitrogen in sediment are found to the north of the active lagoonal fish-cage complexes. The δ13C and δ13N signatures of the organic matter in this area are attributed to input from the surrounding mangrove forest, whereas their distribution is a result of the interaction of tidal currents with the physical presence of fish-farm complexes. The environmental influence of the active fish cages at lagoonal site SET11-S40 is minimal as a result of the flushing effects of tidal currents from a nearby inlet. Further north at the SET11-S43 lagoonal fish-cage complex, which receives less marine influence (lower salinity and reduced tidal currents), organic-rich mud has accumulated beneath and to the north of the complex. Foraminiferal and sedimentological data from abandoned estuarine fish-farm complex SET11-S9A are indistinguishable from those of adjacent estuarine sites indicating a rapid return to pre-fish-farm conditions following abandonment.

Wave-current bottom shear stresses and sediment re-suspension in the mouth bar of the Modaomen Estuary during the dry season

On the basis of the measurement data pertaining to waves, current, and sediment in February 2012 in the mouth bar of the Modaomen Estuary, the Soulsby formulae with an iterative method are applied to calculating bottom shear stresses (BSS) and their effect on a sediment re-suspension. Swell-induced BSS have been found to be the most important part of the BSS. In this study, the correlation coefficient between a wavecurrent shear stress and SSC is 0.86, and that between current shear stresses and SSC is only 0.40. The peaks of the SSC are consistent with the height and the BSS of the swell. The swell is the main mechanism for the sediment re-suspension, and the tidal current effect on sediment re-suspension is small. The peaks of the SSC are centered on the high tidal level, and the flood tide enhances the wave shear stresses and the SSC near the bottom. The critical shear stress for sediment re-suspension at the observation station is between 0.20 and 0.30 N/m2. Tidal currents are too weak to stir up the bottom sediment into the flow, but a WCI (wave-current interaction) is strong enough to re-suspend the coarse sediment.

The role of tides in shelf-scale simulations of the wave energy resource

Many regions throughout the world that are suitable for exploitation of the wave energy resource also experience large tidal ranges and associated strong tidal flows. However, tidal effects are not included in the majority of modelling studies which quantify the wave energy resource. This research attempts to quantify the impact of tides on the wave energy resource of the northwest European shelf seas, a region with a significant wave energy resource, and where many wave energy projects are under development. Results of analysis based on linear wave theory, and the application of a non-linear coupled wave-tide model (SWAN–ROMS), suggest that the impact of tides is significant, and can exceed 10% in some regions of strong tidal currents (e.g. headlands). Results also show that the effect of tidal currents on the wave resource is much greater than the contribution of variations in tidal water depth, and that regions which experience lower wave energy (and hence shorter wave periods) are more affected by tides than high wave energy regions. While this research provides general guidelines on the scale of the impact in regions of strong tidal flow, high resolution site-specific coupled wave-tide models are necessary for more detailed analysis.

Laboratory study on wave dissipation by vegetation in combined current–wave flow

Coastal wetlands such as salt marshes and mangroves provide valuable ecosystem services including coastal protection. Many studies have assessed the influence of plant traits and wave conditions on vegetation-induced wave dissipation, whereas the effect of tidal currents is often ignored. To our knowledge, only two studies investigated wave dissipation by vegetation with the presence of following currents (current velocity is in the same direction as wave propagation) (Li and Yan, 2007; Paul et al., 2012). However, based on independent experiments, they have drawn contradictive conclusions whether steady currents increase or decrease wave attenuation. We show in this paper that this inconsistency may be caused by a difference in ratio of imposed current velocity to amplitude of the horizontal wave orbital velocity. We found that following currents can either increase or decrease wave dissipation depending on the velocity ratio, which explains the seeming inconsistency in the two previous studies. Wave dissipation in plant canopies is closely related to vegetation drag coefficients. We apply a new approach to obtain the drag coefficients. This new method eliminates the potential errors that are often introduced by the commonly used method. More importantly, it is capable of obtaining the vegetation drag coefficient in combined current–wave flows, which is not possible for the commonly used calibration method. Based on laboratory data, we propose an empirical relation between drag coefficient and Reynolds number, which can be useful for numerical modeling. The characteristics of drag coefficient variation and in-canopy velocity dynamics are incorporated into an analytical model to help understand the effect of following currents on vegetation-induced wave dissipation.

A Numerical Model Study on Ice Boom in a Coastal Lake

ABSTRACT Kolerski, T.; Shen, H.T., and Kioka, S., 2013. A numerical model study on ice boom in a coastal lake. A numerical study on the effectiveness of the proposed ice boom to be installed near the entrance of Lake Notoro, Hokkaido, Japan to prevent sea ice moving into the lake is presented. A two-dimensional hydro–ice dynamics model was modified to allow for the treatment of ice-boom interaction with the effect of tidal current. The numerical model is a coupled hydrodynamic and ice dynamic model. The ice dynamic component uses a Lagrangian discrete parcel method based on smoothed particle hydrodynamics. The model was used to assess the dynamics of sea-ice transport into the lake, the effectiveness of the boom on ice retention, and the ice load on boom spans. Results for steady and unsteady simulation cases including wind effect are presented.

Effects of tidal currents on nonlinear internal solitary waves in the South China Sea

The propagation and fission process of internal solitary waves (ISWs) with amplitudes of about 170 m are simulated in the northeast of the South China Sea (NSCS) by using the generalized Korteweg-de Vries (KdV) equation under continuous stratification. More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs. This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current. It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however, there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons (defined as the distance between two neighboring peaks of ISWs). The difference in nonlinearity coefficient α between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons.

Hydrodynamic and sediment dynamic modifications of tidal flow in the near-field area of offshore breakwaters

Numerical modeling was used in order to study the effect of tidal currents within a breakwater scheme that has reached morphodynamic equilibrium. Tidal flow is simulated, using a downscaling procedure from a regional numerical model, in order to investigate the small-scale hydrodynamic modifications caused by the structures in the absence of waves. Sediment transport processes at different stages of the neap and spring tidal cycle are also considered over the entire scheme. Significant modifications to the tidal currents were identified, caused by the presence of the following structures: (1) obstruction of the main tidal flow and (2) flow channelization between the structures and the coastline, leading to flow acceleration over the salients. Furthermore, the effect of the modified tidal regime on bedload sediment transport processes was investigated. The design characteristics of the scheme (i.e., gap width, offshore distance, and relative angle with respect to the tidal currents) are found to influence locally the tidal flow and the bedload transport, over the top of the salients, modulating their growth. Despite being located in a mixed-energy, wave-dominated environment, the shear stress ratio between currents and waves show a dominance of tidal processes at the sheltered areas of the scheme (i.e., behind the breakwaters) that diminishes as the incident wave period increases. Hence, in order to correctly predict the morphological evolution of such coast under the influence of coastal protection schemes, the tidal processes have to be studied in addition to the wave processes.