scholarly journals REDUCED COMPLEXITY MODELING OF SHORELINE RESPONSE BEHIND OFFSHORE BREAKWATERS

2020 ◽  
pp. 34
Author(s):  
Ahmed Elghandour ◽  
Dano Roelvink ◽  
Bas Huisman ◽  
Johan Reyns ◽  
Susana Costas ◽  
...  
Keyword(s):  
Wave Diffraction ◽  
Evolution Model ◽  
Coastal Protection ◽  
Grid System ◽  
Model Free ◽  
Coastline Evolution ◽  
Detailed Modelling ◽  
Longshore Transport ◽  
Wave Heights ◽  
Reduced Complexity

Prediction of the shoreline response behind offshore breakwaters is essential for coastal protection projects. Due to the complexity of the processes behind the breakwaters (e.g., wave diffraction, currents, longshore transport), detailed modelling needs high computational efforts. Therefore, simplifying the process effect in a simpler coastline model could be efficient. In this study, the coastline evolution model ShorelineS is used. A new routine was implemented in the model to adjust the wave heights and angles behind the offshore breakwaters. Two approaches from the literature and a newly introduced one were tested in this study. The model free grid system was used to simply track the breaker line; such an advantage also helped to form tombolo, which is not common for these types of models. The tests showed promising results for single and multi breakwaters systems; however, the newly introduced approach still needs further testing and refinement for better performance and less computational cost.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/mdCpmSQFO1Y

Modeling of wave processes in closed water areas of shallow water areas

2021 ◽  
pp. 30-35
Author(s):  
Eugene Istomin ◽  
Valerii Mikheev ◽  
Yaroslav Petrov ◽  
Irma Martyn
Keyword(s):  
Water Area ◽  
Navier Stokes ◽  
Coastal Protection ◽  
Wave Processes ◽  
Color Palette ◽  
Continuity Equations ◽  
Port Area ◽  
Wave Heights ◽  
Closed Water ◽  
Hydrostatic Model

The article presents the developed non-stationary two-dimensional hydrostatic model of wave propagation in the water area of the port of the Bay of Five Hunters, protected by a coastal protection structure in the form of a jetty. The tasks of the work included the development of a model based on the Navier-Stokes and continuity equations and a long-range assessment of the possible impact of the wave situation on marine objects in the port area. At present, the provision of hydrometeorological predictive information is one of the most important factors in the effective operation of port waters. The results are presented graphically using a geographic information system, where different wave heights and maximum wave amplitudes are displayed using a color palette. The consistency of the obtained results is shown, and refraction, diffraction, and interference are noted for the incoming wavefront.

scholarly journals Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

2020 ◽  
Vol 12 (22) ◽  
pp. 3689
Author(s):  
Iain Fairley ◽  
Jose Horrillo-Caraballo ◽  
Ian Masters ◽  
Harshinie Karunarathna ◽  
Dominic E. Reeve
Keyword(s):  
Spatial Scales ◽  
Coastal Dunes ◽  
Sediment Supply ◽  
Tidal Range ◽  
Coastal Protection ◽  
Dune System ◽  
Pressure Transducers ◽  
Significant Wave ◽  
Wave Heights ◽  
Significant Wave Heights

Coastal dunes have global importance as ecological habitats, recreational areas, and vital natural coastal protection. Dunes evolve due to variations in the supply and removal of sediment via both wind and waves, and on stabilization through vegetation colonization and growth. One aspect of dune evolution that is poorly understood is the longshore variation in dune response to morphodynamic forcing, which can occur over small spatial scales. In this paper, a fixed wing unmanned aerial vehicle (UAV), is used to measure the longshore variation in evolution of a dune system in a megatidal environment. Dune sections to the east and west of the study site are prograding whereas the central portion is static or eroding. The measured variation in dune response is compared to mesoscale intertidal bar migration and short-term measurements of longshore variation in wave characteristics during two storms. Intertidal sand bar migration is measured using satellite imagery: crescentic intertidal bars are present in front of the accreting portion of the beach to the west and migrate onshore at a rate of 0.1–0.2 m/day; episodically the eastern end of the bar detaches from the main bar and migrates eastward to attach near the eastern end of the study area; bypassing the central eroding section. Statistically significant longshore variation in intertidal wave heights were measured using beachface mounted pressure transducers: the largest significant wave heights are found in front of the dune section suffering erosion. Spectral differences were noted with more narrow-banded spectra in this area but differences are not statistically significant. These observations demonstrate the importance of three-dimensionality in intertidal beach morphology on longshore variation in dune evolution; both through longshore variation in onshore sediment supply and through causing longshore variation in near-dune significant wave heights.

Are artificial reefs an appropriate solution to protect the Danube Delta coast?

2020 ◽  
Author(s):  
Irina Dinu
Keyword(s):  
Wave Climate ◽  
Sediment Supply ◽  
Danube River ◽  
Artificial Reefs ◽  
Coastal Protection ◽  
Danube Delta ◽  
Marine Geology ◽  
Natural Habitats ◽  
Wave Heights ◽  
The Impact

<p><strong>Are artificial reefs an appropriate solution to protect the Danube Delta coast?</strong></p><p>Irina Dinu<sup>1</sup>, Vicente Gràcia<sup>2</sup>, Manuel García-León<sup>3</sup>, Adrian Stănică<sup>1</sup></p><p> </p><p><sup>1</sup> – National Institute for Marine Geology and Geoecology (GeoEcoMar), 23-25 Dimitrie Onciul St., 024053, Bucharest, Romania</p><p><sup>2</sup> - Laboratory of Maritime Engineering, Polytechnic University of Catalonia (LIM-UPC), Campus Diagonal Nord, Building D1, 1-3 Jordi Girona St., 08034 Barcelona</p><p><sup>3</sup> - International Centre for Research of Coastal Resources (CIIRC), 1-3 Jordi Girona St., Mòdul D1, Campus Nord, 08003 Barcelona, Spain</p><p> </p><p>The Danube Delta coast is part of the Danube Delta Biosphere Reserve, thus being aimed to preserve its typical natural habitats. Over the last decades, human interventions along the Danube River, as well as coastal navigation and harbour protection works on the Romanian coast have determined the reduction of sediment supply along the Danube Delta coast, which is nowadays affected by erosion on its widest part.</p><p>Sustainable management plans for the Danube Delta coast include the use of working-with-nature solutions.</p><p>In this work, the effect of artificial reefs on the wave heights along the Danube Delta coast is studied. The results of a previous wave climate study and a wave model have been used for this purpose. Simulations have been performed for different setup of artificial reefs and for extreme storms with various return periods. The effect of sea level rise has also been taken into account.</p><p>Our results show that artificial reefs are significantly effective in reducing the wave heights along the Danube Delta coast. However, further detailed analysis concerning the impact of such a coastal protection solution is still needed.  </p>

scholarly journals Wave directional measurement in Patos Lagoon, RS, Brazil

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Natália Lemke ◽  
◽  
Lauro Julio Calliari ◽  
José Antônio Scotti Fontoura ◽  
Déborah Fonseca Aguiar
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Climate ◽  
Coastal Protection ◽  
Peak Period ◽  
Patos Lagoon ◽  
Significant Wave ◽  
Wave Parameters ◽  
Wave Heights ◽  
Significant Wave Heights

ABSTRACT The wave climate characterization in coastal environments is essentially important to oceanography and coastal engineering professionals regarding coastal protection works. Thus, this study aims to determine the most frequent wave parameters (significant wave height, peak period and peak direction) in Patos Lagoon during the period of operation of a directional waverider buoy (from 01/27/2015 to 06/30/2015). The equipment was moored at approximately 14 km from the São Lourenço do Sul coast at the geographic coordinates of 31º29’06” S and 51º55’07” W, with local depth of six meters, registering significant wave height, peak period and peak direction time series. During the analyzed period, the greatest wave frequencies corresponded to short periods (between 2 and 3.5 seconds) and small values of significant wave heights (up to 0.6 meters), with east peak wave directions. The largest wave occurrences corresponded to east peak wave directions (33.3%); peak wave periods between 2.5 and 3 seconds (25.6%) and between 3 and 3.5 seconds (22.1%); and to significant wave heights of up to 0.3 meters (41.2%) and from 0.3 to 0.6 meters (38%). This research yielded unprecedented findings to Patos Lagoon by describing in detail the most occurring wave parameters during the analyzed period, establishing a consistent basis for several other studies that might still be conducted by the scientific community.

scholarly journals APPLICATION OF WAVE DIFFRACTION DATA

1968 ◽  
Vol 1 (11) ◽  
pp. 16 ◽  
Author(s):  
Richard Silvester ◽  
Teck-Kong Lim
Keyword(s):  
Experimental Data ◽  
Diffraction Data ◽  
Wave Diffraction ◽  
Wave Reflection ◽  
Incident Angle ◽  
Spreading Process ◽  
Simple Addition ◽  
Arc Distance ◽  
Diffraction Coefficient ◽  
Wave Heights

By considering separately the two terms of the Sommerfeld solution of wave diffraction behind a semi-infinite breakwater, the influence of the wave reflection from the structure can be evaluated The diffraction coefficient at any point can be obtained from a graph or table for full, partial or no reflection by the simple addition of two coefficients From the similarity of the energy-spreading process to the dam-burst problem, it was found that wave heights decreased consistently along the near circular crests for all distances from the breakwater tip For a workable range of incident angle and distance from the breakwater, wave heights could be defined by this arc distance from the shadow line expressed in wave lengths These relationships have been verified experimentally for all but the smallest incident angle in proximity to the breakwater This can be likened to the dam model in which the dam is moving too slowly to permit normal spreading. The several theoretical solutions for the breakwater gap, when graphed on the same basis, are shown to be very similar, diverging only for small incident angles New parameters are provided which greatly simplify the presentation of information The scatter of past experimental data precludes the verification of this theory and indicates the need for further tests.

scholarly journals GENERALIZED WAVE DIFFRACTION DIAGRAMS

2000 ◽  
Vol 1 (2) ◽  
pp. 2
Author(s):  
J. W. Johnson
Keyword(s):  
Wave Height ◽  
Wave Diffraction ◽  
Water Waves ◽  
Electromagnetic Waves ◽  
Wave Train ◽  
Diffraction Theory ◽  
Long Beach ◽  
Practical Application ◽  
Diffraction Of Light ◽  
Wave Heights

Wave diffraction is the phenomenon in which water waves are propagated into a sheltered region formed by a breakwater or similar barrier which interrupts a portion of a regular wave train (Fig. 1). The principles of diffraction have considerable practical application in connection with the design of breakwaters as discussed by Dunham (1951) at the Long Beach Conference. The phenomenon is analogous to the diffraction of light, sound, and electromagnetic waves. Two general types of diffraction problems usually are encountered: one, the passage of waves around the end of a semi-infinite impermeable breakwater (Putnam and Arthur, 1948), and, second, the passage of waves through a gap in a breakwater (Blue and Johnson, 1949t Carr and Stelzriede, 1951). In general, the theoretical solutions have been found to apply with conservative results, that is, the predicted wave heights in the lee of a breakwater are found to be slightly larger than the height of waves that may be expected under actual conditions. The use of the diffraction theory in breakwater design is made convenient when summarized in the form of diagrams with curves of equal values of diffraction coefficients on a coordinate system in which the origin of the Bystem is at the tip of a single breakwater (Figs. 2a-2b, and 3) or at the center of a gap (Figs. 2c, and 4-6). The diffraction coefficient in this instance is defined as the ratio of the diffracted wave height to the incident wave height and usually is designated by the symbol K». The procedure in preparing diffraction diagrams appears elsewhere (Johnson, 1950). The purpose of this paper is to present diffraction diagrams to supplement the material of Dunham (1951). For complete details on the application of diffraction diagrams to typical harbor problems the reader is referred to this latter paper.

scholarly journals The Coastline Evolution Model 2D (CEM2D) V1.1

2021 ◽  
Vol 14 (9) ◽  
pp. 5507-5523
Author(s):  
Chloe Leach ◽  
Tom Coulthard ◽  
Andrew Barkwith ◽  
Daniel R. Parsons ◽  
Susan Manson
Keyword(s):  
Sediment Transport ◽  
Three Dimensional ◽  
Transport Processes ◽  
Evolution Model ◽  
One Dimensional ◽  
Coastline Evolution ◽  
Fundamental Cause ◽  
Formation And Evolution ◽  
Three Dimensional Models ◽  
Variable Water

Abstract. Coasts are among the most intensely used environments on the planet, but they also present dynamic and unique hazards, including flooding and erosion. Sea level rise and changing wave climates will alter patterns of erosion and deposition, but some existing coastline evolution models are unable to simulate these effects due to their one-dimensional representation of the systems or the sediment transport processes. In this paper, the development and application of the Coastline Evolution Model 2D (CEM2D) are presented, a model which incorporates these influences. The model has been developed from the established CEM and is capable of simulating fundamental cause–effect relationships in coastal systems. The two-dimensional storage and transport of sediment in CEM2D, which are only done in one-dimension in CEM, mean it is also capable of exploring the influence of a variable water level on sediment transport and the formation and evolution of morphological features and landforms at the mesoscale. The model sits between one-dimensional and three-dimensional models, with the advantage of increased complexity and detail in model outputs compared to the former but with more efficiency and less computational expense than the latter.

scholarly journals LONG-TERM DUNE EVOLUTION UNDER INTERACTING CROSS-SHORE AND LONGSHORE PROCESSES

2018 ◽  
pp. 73
Author(s):  
Caroline Fredriksson ◽  
Bas Huisman ◽  
Magnus Larson ◽  
Hans Hanson
Keyword(s):  
Time Scales ◽  
Coastal Dunes ◽  
Field Studies ◽  
Data Set ◽  
Coastline Evolution ◽  
Longshore Transport ◽  
Storm Impact ◽  
Erosion Mitigation ◽  
Semi Empirical

Coastal dunes play an important role in flood protection and erosion mitigation along sandy coasts. Still, few models are available that predict long-term dune evolution. Dune processes are typically modeled at shorter time scales, focusing on storm impact. Meanwhile, long-term coastline evolution models typically ignore exchange of sediment between the beach and the dune. Instead, these models often consider a fixed profile that moves seaward or landward if gradients in the longshore transport are negative or positive, respectively. Nevertheless, it is evident from field studies and morphological models that longshore transport gradients provide a relevant contribution to both beach and dune evolution (Psuty, 1988), and that the dune and the beach respond to sediment budget changes at different time scales (Stive et al., 2002). As a step towards bridging the gap between nearshore, beach, and dune modelling, this study investigates the interaction between longshore transport gradients and the beach and dune evolution on decadal time scales. This aim is addressed by combining an analysis of a 22- year long data set at IJmuiden (The Netherlands; see Figure 1) with simulations using a semi-empirical crossshore model, the CS-model (Larson et al., 2016).

Efficient Non-Hydrostatic Modeling for Free Surface Waves in Deep and Shallow Water

2009 ◽  
Author(s):  
Chin H. Wu ◽  
Chih-Chieh Young
Keyword(s):  
Free Surface ◽  
Wave Dispersion ◽  
Wave Transformation ◽  
Dispersion Property ◽  
Linear Wave ◽  
Grid System ◽  
Model Free ◽  
Reference Velocity ◽  
Novel Approach ◽  
Hydrostatic Model

A novel approach that introduces the Boussinesq-type like equations into an implicit non-hydrostatic model, free of irrotational flow assumption, is presented. The basic concept is to obtain an analytical-based form of pressure distribution at the top layer by matching the reference velocity under a virtual grid system with the one under a non-hydrostatic model grid system. Locations of the references velocities are tuned to optimize the linear wave dispersion property in the model. Efficiency of this non-hydrostatic model with Boussinesq-type equations (NHM-BTE) is critically examined through several free-surface wave examples. Overall model results show that NHM-BTE using only a few vertical layers (i.e., two ∼ four) is capable of accurately simulating highly dispersive wave motion and wave transformation over irregular bathymetry.

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