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ENGINEERING (1225 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
AASRI Procedia     Open Access   (Followers: 14)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 271)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 4)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 12)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 43)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 17)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 8)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 26)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 280)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 206)
Composites Part B : Engineering     Hybrid Journal   (Followers: 259)
Composites Science and Technology     Hybrid Journal   (Followers: 200)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 7)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        1 2 3 4 5 6 7 | Last

Journal Cover Coastal Engineering
  [SJR: 1.999]   [H-I: 74]   [11 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0378-3839
   Published by Elsevier Homepage  [3177 journals]
  • Large impulsive forces on recurved parapets under non-breaking waves. A
           numerical study
    • Abstract: Publication date: June 2018
      Source:Coastal Engineering, Volume 136
      Author(s): M. Castellino, P. Sammarco, A. Romano, L. Martinelli, P. Ruol, L. Franco, P. De Girolamo
      This paper describes 2-D numerical simulations of velocity and pressure fields generated by non-breaking waves on a vertical breakwater with a recurved parapet wall. The influence of the geometrical characteristics of the parapet is investigated. An impulsive pressure force is identified and discussed with respect to the pure vertical wall case. This force is generated by the seaward flow confinement induced by the surging wave crest. We refer to this impulsive impact as “confined-crest impact”. A large part of the vertical wall is affected by an impulsive increase in pressure caused by pulsating wave, compared to the case where the parapet is completely vertical. The maximum values of the impulsive pressures are localized under the recurved parapet. The total force increase on the entire structure may be significant when compared to the pure vertical wall case.

      PubDate: 2018-02-26T10:42:38Z
  • Effects of submerged berms on the stability of conventional rubble mound
    • Abstract: Publication date: June 2018
      Source:Coastal Engineering, Volume 136
      Author(s): D. Celli, D. Pasquali, P. De Girolamo, M. Di Risio
      Berms deployed at the toe of conventional breakwaters may be needed to reduce bottom settlements and to limit scour in front of the structure due to coastal currents. In the mean time, they may be effective in increasing the stability of the armor layer and also in minimizing the wave overtopping discharge compared to straight sloped conventional breakwaters without a berm. This research aims to provide a new design criterion for the armor layer of conventional breakwaters with submerged berms marked by small thickness compared to water depth. Indeed, past researches focused on the influence of relatively high berms on the stability of the armor layer. The design of the berm itself is not tackled herein. The effects of submerged berms on the incident waves transformation have been evaluated by means of a numerical model, validated by using experimental data. Then, a parametric correction factor of the incident significant wave height at the toe of the structure is provided and included in well established design criteria. The experimental comparison confirms the reliability of the proposed method by highlighting the importance to use design criteria within their validity ranges, in order to avoid an unsafe dimensioning of the armor elements.

      PubDate: 2018-02-26T10:42:38Z
  • Wave attenuation across a tidal marsh in San Francisco Bay
    • Abstract: Publication date: June 2018
      Source:Coastal Engineering, Volume 136
      Author(s): M.R. Foster-Martinez, J.R. Lacy, M.C. Ferner, E.A. Variano
      Wave attenuation is a central process in the mechanics of a healthy salt marsh. Understanding how wave attenuation varies with vegetation and hydrodynamic conditions informs models of other marsh processes that are a function of wave energy (e.g. sediment transport) and allows for the incorporation of marshes into coastal protection plans. Here, we examine the evolution of wave height across a tidal salt marsh in San Francisco Bay. Instruments were deployed along a cross-shore transect, starting on the mudflat and crossing through zones dominated by Spartina foliosa and Salicornia pacifica. This dataset is the first to quantify wave attenuation for these vegetation species, which are abundant in the intertidal zone of California estuaries. Measurements were collected in the summer and winter to assess seasonal variation in wave attenuation. Calculated drag coefficients of S. foliosa and S. pacifica were similar, indicating equal amounts of vegetation would lead to similar energy dissipation; however, S. pacifica has much greater biomass close to the bed (<20 cm) and retains biomass throughout the year, and therefore, it causes more total attenuation. S. foliosa dies back in the winter, and waves often grow across this section of the marsh. For both vegetation types, attenuation was greatest for low water depths, when the vegetation was emergent. For both seasons, attenuation rates across S. pacifica were the highest and were greater than published attenuation rates across similar (Spartina alterniflora) salt marshes for the comparable depths. These results can inform designs for marsh restorations and management plans in San Francisco Bay and other estuaries containing these species.

      PubDate: 2018-02-26T10:42:38Z
  • Infragravity swash parameterization on beaches: The role of the profile
           shape and the morphodynamic beach state
    • Abstract: Publication date: June 2018
      Source:Coastal Engineering, Volume 136
      Author(s): Paula Gomes da Silva, Raúl Medina, Mauricio González, Roland Garnier
      A field campaign was undertaken at Somo beach in northern Spain, with the aim of understanding the processes involved in the generation of low frequency swash. Taking the parameterization presented in earlier studies as a starting point, a novel empirical model was defined based on a database which included datasets from Somo beach and from 9 other experiments. This new parameterization was obtained by relating the horizontal cross-shore component of the infragravity swash to the foreshore slope and the morphodynamic beach state through the non-dimensional fall velocity parameter. The role of previous sea states when determining the morphodynamic beach state was also assessed. A strong correlation between low frequency oscillations and the morphology of the beach was verified, resulting in a substantial improvement over existing infragravity swash predictions proposed in the literature.

      PubDate: 2018-02-26T10:42:38Z
  • Modelling the effect of suspended load transport and tidal asymmetry on
           the equilibrium tidal sand wave height
    • Abstract: Publication date: June 2018
      Source:Coastal Engineering, Volume 136
      Author(s): W. van Gerwen, B.W. Borsje, J.H. Damveld, S.J.M.H. Hulscher
      Tidal sand waves are rhythmic bed forms found in shallow sandy coastal seas, reaching heights up to ten meters and migration rates of several meters per year. Because of their dynamic behaviour, unravelling the physical processes behind the growth of these bed forms is of particular interest to science and offshore industries. Various modelling efforts have given a good description of the initial stages of sand wave formation by adopting a linear stability analysis on the coupled system of water movement and the sandy seabed. However, the physical processes causing sand waves to grow towards equilibrium are far from understood. We adopt a numerical shallow water model (Delft3D) to study the growth of sand waves towards a stable equilibrium. It is shown that both suspended load transport and tidal asymmetry reduce the equilibrium sand wave height. A residual current results in asymmetrical bed forms that migrate in the direction of the residual current. The combination of suspended load transport and tidal asymmetry results in predicted equilibrium wave heights comparable to wave heights found in the field.

      PubDate: 2018-02-26T10:42:38Z
  • Modeling hurricane-induced wetland-bay and bay-shelf sediment fluxes
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): Ke Liu, Qin Chen, Kelin Hu, Kehui Xu, Robert R. Twilley
      Hurricanes have long been recognized as a strong forcing in shaping the coastal morphology, especially by redistributing sediments among coastal wetlands, bays and inner continental shelves. However, the contribution of hurricane-induced sediment transport to the sediment budget of a shelf – bay – wetland system has not been evaluated using a physics-based numerical model. There is a particular confusion on how sediment transport to coastal wetlands contributes to sediment accretion in wetlands and thus wetland adaptation to sea level rise. In this paper, we present a coupled modeling system for hurricane winds, storm surge, waves and sediment transport on the Louisiana coast, and use it to investigate two fundamental questions: (1) How much sediment is transported and deposited on coastal wetlands during a major hurricane event like Hurricane Gustav (2008), and (2) where is the source of the deposited sediment on the wetland soil surface. Our model successfully reproduced the measured basin-averaged sediment accretion in the Terrebonne and Barataria Basins after Gustav, and estimated that Hurricane Gustav imported approximately 27 million metric tons of sediment on wetlands in that area. The estimated deposition was mainly made up of mud suspended from the coastal bays, and the contribution of this sediment to wetland deposition was 88.7% in Terrebonne Bay and 98.2% in Barataria Bay within the tested range of sediment properties. This paper demonstrates a useful tool to help understand how sediment dynamics in the coastal zone during hurricane events play a significant role in the sediment budget of a deltaic coast.

      PubDate: 2018-02-26T10:42:38Z
  • Modeling multivariate ocean data using asymmetric copulas
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): Yi Zhang, Chul-Woo Kim, Michael Beer, Huliang Dai, Carlos Guedes Soares
      Multivariate descriptions of ocean parameters are quite important for the design and risk assessment of offshore engineering applications. A reliable and realistic statistical multivariate model is essential to produce a representative estimate of the sea state for understanding the ocean conditions. Therefore, an advanced modeling of ocean parameters helps towards improving ocean and coastal engineering practices. In this paper, we introduce the concepts of asymmetric copulas for the modeling of multivariate ocean data. In contrast to extensive previous research on the modeling of symmetric ocean data, this study is focused on capturing asymmetric dependencies among the environmental parameters, which are critical for a realistic description of ocean conditions. This involves particular attention to both nonlinear and asymmetrically dependent variates, which are quite common for the ocean variables. Several asymmetric copula functions, capable of modeling both linear and nonlinear asymmetric dependence structures, are examined in detail. Information on tail dependencies and measures of asymmetric dependencies are exploited. To demonstrate the advantages of asymmetric copulas, the asymmetric copula concept is compared with the traditional copula approaches from the literature using actual environmental data. Each of the introduced copula models is fitted to a set of ocean data collected from a buoy at the US coast. The performance of these asymmetric copulas is discussed and compared based on data fitting and tail dependency characterizations. The accuracy of asymmetric copulas in predicting the extreme value contours is discussed.

      PubDate: 2018-02-26T10:42:38Z
  • An integrated framework of Extreme Learning Machines for predicting scour
           at pile groups in clear water condition
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): Isa Ebtehaj, Hossein Bonakdari, Fatemeh Moradi, Bahram Gharabaghi, Zohreh Sheikh Khozani
      In this study, an integrated framework of Extreme Learning Machines (ELM) was developed to predict local scour depth around pile groups in clear water. The effective variables on local scour at pile groups include flow characteristics upstream of the piles, critical flow conditions related to the incipient motion of particles, pile spacing arrangement, geometric properties and bed particle size. The ELM network was trained and tested using dimensional datasets collected from extensive experiments reported in the literature. The ELM network testing results were compared with a support vector machine (SVM) and artificial neural network (ANN). The most effective variable on local scour depth at pile groups was determined using different sets of input combinations. The proposed ELM model produced a lower error in predicting local scour depth at pile groups than other existing models (R 2  = 0.99; MAPE = 8.75; RMSE = 0.007). The ELM model results were compared with existing artificial intelligence-based and regression-based models. The results indicate that ELM outperformed the existing methods with a high level of accuracy. Moreover, according to an uncertainty analysis of scour depth prediction by the proposed and existing models, the least uncertainty band width for ELM was ±0.0011 compared to ±0.0014 for the best existing model. Moreover, an ELM-based equation was proposed for use in practical engineering. Furthermore, a sensitivity analysis was done to study the effect of each variable on the ELM-based equation proposed.

      PubDate: 2018-02-05T06:38:02Z
  • Bayesian Networks in coastal engineering: Distinguishing descriptive and
           predictive applications
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): T. Beuzen, K.D. Splinter, L.A. Marshall, I.L. Turner, M.D. Harley, M.L. Palmsten
      Bayesian networks (BNs) are increasingly being used to model complex coastal processes due to their ability to integrate non-linear systems, their transparent probabilistic framework, and low computational cost. A BN may be suited to descriptive or predictive application. Descriptive BNs are highly calibrated models that are useful for better understanding the physics and causal relationships driving a system. Predictive BNs are generalisations of a system that have skill at predicting outside of the training domain. The predictive and descriptive usefulness of a BN depends on its complexity and the amount of data available to train it, but there is often a trade-off; higher descriptive skill comes at the cost of reduced predictive skill. To demonstrate the differences between predictive and descriptive BNs in a coastal engineering context, a BN to predict shoreline recession caused by coastal storm events is developed and tested using an extensive 10-year dataset incorporating 137 individual storms events monitored at Narrabeen-Collaroy Beach, Australia. A parsimonious approach to BN development is used to separately determine the optimum predictive and descriptive BNs for this dataset. Results show that for this dataset two quite different BNs can be developed: one that is optimized to achieve the highest predictive skill, and a second network that is optimized to maximize descriptive skill. The optimum predictive BN is found to comprise 3 nodes (variables) and can predict the shoreline recession caused by unseen storm events with a skill of 65%. The optimum descriptive BN is composed of 5 nodes and can reproduce 88% of the training dataset, but with more limited predictive capabilities. The uses and limitations of these two different approaches to BN formulation are illustrated with example applications to coastal process modelling. It is anticipated that the insights provided in this paper will help to clarify the further development of Bayesian Networks applied to coastal modelling.

      PubDate: 2018-02-05T06:38:02Z
  • Statistical distribution of wave-induced drift for random ocean waves in
           finite water depth
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): Jinbao Song, Hailun He, Anzhou Cao
      Based on the linear random wave solutions of water wave equations in finite water depth, a theoretical statistical distribution of the wave-induced drift is derived. The parameters involved in the distribution can be determined by the water depth and the wave spectrum of ocean waves. As an illustrative example, we consider a simple wind-generated sea and the parameters are calculated for typical wind speeds and water depths by using Phillips spectrum. The behaviours of the distribution and the effects of wind speed and water depth on the distribution are investigated.

      PubDate: 2018-02-05T06:38:02Z
  • Stability of rubble-mound breakwaters under tsunami first impact and
           overflow based on laboratory experiments
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): Íñigo Aniel-Quiroga, César Vidal, Javier L. Lara, Mauricio González, Álvaro Sainz
      Recent tragic tsunami events, like those that occurred in the Indian Ocean in 2004, and in Japan in 2011, have revealed the need of further work to reduce tsunami risk in coastal areas. An important aspect towards risk reduction is the study of the interaction between tsunami waves and coastal structures as these are the first to receive the tsunami's energy. Dikes and breakwaters must have an adequate structural behavior and maintain some functionality and operability under tsunami attacks to be able to contribute to the reduction of its consequences. Within this scope, laboratory experiments on scaled models of two typical Mediterranean rubble-mound breakwater typologies under tsunami waves were conducted for the first time. The tsunami's action was split into 2 parts: (1) the first impact of solitons was tested by means of large solitary waves and, (2) the subsequent overflow was approached by applying a pump-driven wave maker. The damage on the breakwaters due to these actions was measured and assessed. The result is an in-deep analysis of the relationships among Stability Number, Damage Level and Number of tsunami waves. The outcome of this analysis includes the development of a set of formulae that provide, in the range of the conducted tests, the value of the Damage Parameter, so that tsunami actions can be taken into account in the design of rubble mound structures. Finally, based on the results of these experiments, the threshold values of the Damage Parameter used to characterize damage in armors (Initiation of damage, initiation of destruction, destruction) was particularized for tsunami actions.

      PubDate: 2018-02-05T06:38:02Z
  • Sensitivity of rip current forecasts to errors in remotely-sensed
    • Abstract: Publication date: May 2018
      Source:Coastal Engineering, Volume 135
      Author(s): M. Radermacher, M.A. de Schipper, A.J.H.M. Reniers
      Operational nearshore current forecasts based on numerical model simulations are gaining popularity as a measure to increase the safety of swimmers. Applying remotely-sensed bathymetry in these model simulations is often proposed in order to cope with rapidly changing nearshore bathymetry. Errors in the remotely-sensed bathymetry may negatively affect performance of the hydrodynamic model. Hence, this study aims to determine the sensitivity of modelled nearshore currents (with a strong focus on rip currents) to errors in remotely-sensed bathymetries. The errors in the remotely-sensed bathymetries (depth inversion algorithm applied to video stream) were quantified with a length scale-aware validation technique, providing useful insights in the contribution of pattern and amplitude errors to the total error throughout the analysis domain and over a range of bathymetric length scales. Subsequently, simulations with a nearshore hydrodynamic model were performed, using both in-situ and remotely-sensed bathymetries as an input. A comparison of predicted rip currents on either bathymetry yielded performance statistics for operational current forecasts on remotely-sensed bathymetries, taking the model with in-situ bathymetry as a reference. Linking these performance statistics back to the quantified errors in the remotely-sensed bathymetry finally revealed the relation between errors in flow and bathymetry. Of all rip currents generated on an in-situ bathymetry, 55% were reproduced on the remotely-sensed bathymetry, showing that models predicting nearshore currents on remotely-sensed bathymetry have predictive value. Positive rip current predictions were promoted significantly by accurate reproduction of the pattern and amplitude of nearshore bars at length scales between 200 and 400 m. In contrast to the length-scale aware validation technique applied here, commonly used domain-wide bulk error metrics lack important information about spatial variations in the quality of remotely-sensed bathymetry.

      PubDate: 2018-02-05T06:38:02Z
  • Large Eddy Simulation of near-bed pipelines in oscillatory flow
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Efstratios N. Fonias, Dimokratis G.E. Grigoriadis
      A series of unsteady, three-dimensional numerical simulations of the incompressible, oscillatory flow around a near-bed pipeline is presented. A flow at Reynolds number equal to Re α o = 20,000 with respect to the oscillatory amplitude and maximum oscillation velocity is considered. The ratio of the pipeline diameter to the oscillatory amplitude examined is in the range of D / α o = 0.1 − 1.0 , with the pipeline located at a distance of G / D = 0.0 − 1.0 . The numerical simulations are conducted by means of Large Eddy Simulation (LES), using Cartesian grids. The presence of solid boundaries is taken into account by means of the Immersed Boundary method. For turbulence modelling, two different subgrid scale models are tested, the classical Smagorinsky and the Filtered Structure Function (FSF) models. The results in terms of vortex shedding are compared against previously reported data demonstrating very good agreement. Vortex shedding patterns are presented, indicating suppression of the boundary layer separation of the lower side of the pipeline for gap lengths G / α o ≤ 1 / 20 . The characteristic values of the hydrodynamic forcing in terms of the drag and lift coefficients and the three significant oscillation frequencies extracted from the temporal variation of the forcing signals are associated with the flow regimes and wall proximity. The pipeline experiences hydrodynamic loading which is found to oscillate with the external flow frequency along the direction of the flow. Along the wall-normal direction, the forces exerted on the pipe oscillate with several frequencies of high power spectral density. However, the three significant oscillation frequencies of the lift coefficient appear to have almost constant values. The presented results can provide trends for design purposes in similar flow conditions for a wide range of engineering applications.

      PubDate: 2018-02-05T06:38:02Z
  • Tidal inlets and estuaries: Comparison of Bruun, Escoffier, O'Brien and
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): J.B. Hinwood, E.J. McLean
      The authors have shown previously that over very long time scales a barrier estuary or tidal inlet will tend towards one of two states, called attractors. In this paper it is shown how that analysis represents an extension and generalisation of three earlier procedures. There are three widely recognised quantitative semi-empirical procedures describing the long term equilibrium dimensions of the entrance channel of barrier estuaries and tidal inlets. The best known of these laws is the tidal prism-entrance area relation, often referred to as the O'Brien equation. The second procedure is based on the Escoffier or closure diagram, comprising a simple hydrodynamic relationship between the entrance area and the entrance velocity together with an empirical "equilibrium velocity". The third is the set of rules developed by Bruun that relate the entrance channel stability to the longshore sediment supply and the entrance channel sediment transport capacity. Each of these is based on major simplifications that restrict its utility and range of validity more than is usually recognised. The attractor analysis, while still based on a lumped model, adds sediment transport and deposition/scour equations and enables the use of more realistic entrance hydrodynamics. It predicts the rates of change and presents the results on a practical “attractor map”. The predictions of the three empirical laws are compared with the attractor map and their practical application is critically compared. The empirical laws are shown to provide broadly equivalent predictions to the attractor map, but over limited ranges of estuary conditions. In particular, none of the empirical laws identifies the entrance closure state or describes conditions near closure.

      PubDate: 2018-02-05T06:38:02Z
  • Transformed Rayleigh distribution of trough depths for stochastic ocean
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Yingguang Wang
      This paper deals with the calculation of wave trough depths exceedance probabilities for stochastic ocean waves, and a Transformed Rayleigh method is proposed for carrying out the calculation. In the proposed Transformed Rayleigh method, the transformation model is chosen to be a monotonic exponential function, calibrated such that the first three moments of the transformed model match the moments of the true process. The detailed mathematical procedures and formulas of the proposed Transformed Rayleigh method are given in this article, and the second order Stokes wave model has been integrated into this Transformed Rayleigh method. The proposed new method has been applied for calculating the wave trough depths exceedance probabilities of two sea states, one with the surface elevation data measured at the coast of Yura in the Japan Sea, and another one with the surface elevation data measured at the North Sea. It is demonstrated that the proposed new method can offer better predictions than those from using the theoretical Rayleigh wave trough depths distribution model. The calculation results from using the proposed new method are further compared with those obtained from using the Arhan and Plaisted nonlinear distribution model and the Toffoli et al. wave trough depths distribution model, and the accuracy of the new method has been once again substantiated. The research findings gained from this study demonstrate that the proposed Transformed Rayleigh method can be readily utilized in the process of designing various kinds of ocean engineering structures.

      PubDate: 2018-02-05T06:38:02Z
  • On the accuracy of automated shoreline detection derived from satellite
           imagery: A case study of the sand motor mega-scale nourishment
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Gerben Hagenaars, Sierd de Vries, Arjen P. Luijendijk, Wiebe P. de Boer, Ad J.H.M. Reniers
      Measured trends and variability in shoreline position are used by coastal managers, scientists and engineers to understand and monitor coastal systems. This paper presents a new and generic method for automated shoreline detection from the largely unexplored collection of publicly available satellite imagery. The position of the obtained Satellite Derived Shoreline (SDS) is tested for accuracy for 143 images against high resolution in-situ data along a coastal stretch near the Sand Motor, a well-documented mega-scale nourishment along the Dutch coast. In this assessment, we quantify the effects of potential inaccuracy drivers such as the presence of clouds and wave-induced foam. The overall aim of this study is to verify whether the SDS is suitable to study structural coastline trends for coastal engineering practice. In the ideal case of a cloud free satellite image without the presence of waves, with limited morphological changes between the time of image acquisition and the date of the in-situ measurement, the accuracy of the SDS is with subpixel precision (smaller than 10–30 m, depending on the satellite mission) and depends on intertidal beach slope and image pixel resolution. For the highest resolution images we find an average offset of 1 m between the SDS position and the in-situ shoreline in the considered domain. The accuracy deteriorates in the presence of clouds and/or waves on the image, satellite sensor corrections and georeferencing errors. The case study showed that especially the presence of clouds can lead to a considerable seaward offset of the SDS of multiple pixels (e.g. order 200 m). Wave-induced foam results in seaward offsets in the order of 40 m. These effects can largely be overcome by creating composite images, which results in a continuous dataset with subpixel precision (10–30 m, depending on the satellite mission). This implies that structural trends can be detected for coastlines that have changed with at least the pixel resolution within the considered timespan. Given the accuracy of composite images along the Sand Motor in combination with the worldwide availability of public satellite imagery covering the last decades, this technique can potentially be applied at other locations with large (structural) coastline trends.

      PubDate: 2018-02-05T06:38:02Z
  • Probabilistic mapping of storm-induced coastal inundation for climate
           change adaptation
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Ning Li, Yoshiki Yamazaki, Volker Roeber, Kwok Fai Cheung, Gary Chock
      This paper describes a probabilistic approach for mapping of coastal flood hazards associated with sea-level rise and storm intensification toward the end of the 21st century. Under the Representative Concentration Pathway (RCP) 8.5, the Coupled Model Intercomparison Project Phase 5 (CMIP5) predicts a 0.6-m ensemble mean of sea-level rise for the Central Pacific from the 1986–2005 to 2081–2100 epochs. Fifty downscaling simulations of the 2080–2099 period from the CMIP5 NCAR-CCSM4 model produce 2492 hurricanes around the Hawaiian Islands. In comparison with a control dataset for the 1980–1999 period, the simulated future hurricanes show a slight increase in number and a northward shift of the tracks toward the Hawaiian Islands. There are 627 hurricanes in the 2080–2099 dataset with potential impact on Oahu, and the top 24 storms selected by wind speed at the urban Honolulu coast define a scenario set for inundation mapping. A suite of spectral wave, circulation, and Boussinesq models in a nested grid system describes generation and propagation of surge and waves across the ocean as well as wave setup and runup at the coast. The interoperable package includes phase-averaged and phase-resolving processes to determine the coastal flood hazards over a range of spatial and temporal scales during a hurricane event. Since the simulated dataset corresponds to a quasi 1000-year period, barring the tail end of the distribution, the suite of inundation scenarios enables definition of flood hazard maps with return periods of up to 500 years or annual exceedance probabilities of 0.2% or greater for climate change adaptation.

      PubDate: 2018-02-05T06:38:02Z
  • Flow mechanism of impulsive wave forces and improvement on hydrodynamic
           performance of a comb-type breakwater
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Zhipeng Zang, Zhuo Fang, Ningchuan Zhang
      The interactions between waves and a comb-type breakwater (CTB) are numerically simulated in a 3D numerical wave flume, which is based on an internal wave generation method. The comb-type breakwater (CTB) is a new type of gravity breakwater and evolved from the conventional caisson breakwater, with part of the rectangular caisson being replaced by a thin side plate. Thus, a chamber is formed by the side plate and the bottom of superstructure between two adjacent rectangular caissons. It is found that impulsive wave pressure on the CTB is mainly induced by the chamber, which can be simplified into a vertical wall with a horizontal cantilever slab in the 2D cross-section. The synchronous analyses on wave profiles, velocity vectors, vorticity contours and wave pressure distributions are conducted to reveal the flow mechanism of the impulsive wave force. In the previous studies, the impulsive wave pressure on a vertical wall with a horizontal cantilever slab was merely observed under breaking or broken wave conditions. However, in the present results, the impulsive wave pressure was also observed on such structure under non-breaking waves. The impulsive wave force occurs when the incident wave height is comparable to the clearance between the still water level and the bottom of the super structure for non-breaking waves. Then, a non-dimensional governing parameter, which included the effects of the water depth, the bottom of the superstructure and the incident wave height, was proposed to quantify the critical conditions for impulsive wave force. Finally, a concept designs of openings on the bottom of the superstructure is proposed to reduce the impulsive wave force. The results show that even a 20% opening on the bottom of superstructure can reduce the maxima of impulsive wave pressure by up to 40%.

      PubDate: 2018-02-05T06:38:02Z
  • On the influence of wave breaking on the height limits of two-dimensional
           wave groups propagating in uniform intermediate depth water
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Arvin Saket, William L. Peirson, Michael L. Banner, Michael J. Allis
      The empirical non-dimensionalisation of Nelson (1994) for determining wave height limits are critically reviewed using data assembled from recent studies of wave groups propagating in water of constant depth in the laboratory. The limiting wave height to water depth ratios of marginally breaking deep and intermediate water waves remain within 10% of Nelson's values. However, it is shown that the effect of wave grouping can produce waves in shallower water that are at least 30% greater in height than the limit proposed by Nelson (1994). The present study supports use of limits based on McCowan (1894) and Miche (1944) for coastal engineering design for marginal breaking waves and strongly-breaking deep water waves. Three-dimensional and more strongly breaking waves in shallower water may yield wave heights higher than those measured during this study. The present study provides more robust and universal characterisation of breaking in transitional water than previously determined by geometric wave observations. Using the same measurement techniques as those of Saket et al. (2017), we have investigated the breaking threshold proposed by Barthelemy et al. (2018) but for different classes of unforced unidirectional wave groups in intermediate water depths. The threshold parameter B x = U s /C (where U s is the horizontal surface water particle velocity at the wave crest and C is the wave crest point speed) which distinguishes breaking from non-breaking waves was found to be 0.835 ± 0.005 with the experimental uncertainty of each data point of ±0.020. This threshold is applicable to water depth to wavelength ratios as low as 0.2 including the deep water conditions investigated by Saket et al. (2017). No dependence on peak spectral wavenumber was found.

      PubDate: 2018-02-05T06:38:02Z
  • Dynamic equilibrium planform of embayed beaches: Part 1. A new model and
           its verification
    • Abstract: Publication date: Available online 3 February 2018
      Source:Coastal Engineering
      Author(s): Ahmed I. Elshinnawy, Raúl Medina, Mauricio González
      Equilibrium beach formulations are useful tools for diagnosing and managing coastal engineering problems, providing solutions for beach erosion problems. Headland Bay Beaches (HBBs) can be used as equilibrium coastal systems for stabilizing coastlines and mitigating erosion problems. These embayed beaches may exist in a state of static or dynamic equilibrium. Throughout the literature, several equations can be found for obtaining the Static Equilibrium Planform (SEP) of Headland Bay Beaches (HBBs) with almost negligible net littoral drift rates. However, the formulations used to define the Dynamic Equilibrium Planform (DEP) of embayed beaches with specific net sediment transport rates are scarce, and based on a limited number of studies. This paper proposes a new derived formula for obtaining the planform shape of HBBs in dynamic equilibrium conditions. The formula represents a general form of the Parabolic Bay Shape Equation (PBSE) with modified coefficients as a function of both the wave obliquity (β) and the net littoral drift rate passing through the bay (Q). The angular difference (γ d ) between the direction of the mean wave energy flux at the diffraction point of the headland and the beach orientation down-coast is also incorporated in the proposed formula. The model was verified against natural HBBs in dynamic equilibrium with different net littoral drift rates along the Brazilian coast, producing good results.

      PubDate: 2018-02-05T06:38:02Z
  • Scarping of artificially-nourished mixed sand and gravel beaches:
           Sedimentological characteristics of Hayling Island beach, Southern England
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): S.D. Zarkogiannis, G. Kontakiotis, M.I. Vousdoukas, A.F. Velegrakis, M.B. Collins, A. Antonarakou
      Beach cliffing is a wide-spread characteristic of artificially-replenished beaches, which has many undesirable engineering, environmental and economic consequences. A sedimentological study undertaken on the replenished mixed gravel and sand beach of Hayling Island (southern England) has shown that the persisting beach cliff consists typically of three distinct layers. The textural, geochemical and mineralogical analyses of the deposit showed that the development of the cliff, and particularly the formation of the intermediate, densely-packed layer, could be attributed to a series of processes. Firstly, the techniques used to emplace the recharge material on the beach (i.e. placement by heavy dumper trucks/bulldozers) result in a compaction and grain-fracture of the recharge material, and therefore a denser packing arrangement than that expected by its textural characteristics alone. Secondly, percolating water transfers medium- and fine-grained material to deeper parts of the deposit, resulting in the clogging of the interstices between the gravels and the formation of a densely-packed, poorly-sorted layer. The above processes promote the interactions between the clay minerals of the deposit with [Ca 2+ ] cations, resulting in the formation of particular cementing materials, such as Calcium Silicate Hydrates (CSH).

      PubDate: 2017-12-26T18:36:37Z
  • Hysteresis in the evolution of beach profile parameters under sequences of
           wave climates - Part 2; Modelling
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): F. Birrien, A. Atkinson, T. Shimamoto, T.E. Baldock
      Disequilibrium-type models for two beach profile parameters, P, the shoreline position and net bulk sediment transport, are developed for laboratory experiments that demonstrate morphological hysteresis in the evolution to equilibrium of beach profiles under sequences of different wave climates. The model principle follows the classical disequilibrium approach but with non-monotonic relationships between the forcing and the chosen beach profile parameter at equilibrium, P eq , previously verified and presented in part 1 of this work (Baldock et al., 2017). Two such relationships are required to model beach profile evolution that exhibits morphological hysteresis. The model coefficients are derived for monochromatic and random wave experiments and subsequently used to model data obtained from cyclic erosive and accretive wave conditions of shorter durations, alternating through multiple cycles. In these conditions equilibrium conditions were not reached and hysteresis does not occur. The model is used to investigate the morphological feedback between the outer and inner bars and the resulting behaviour of the bulk transport, and the relative depth over the bar crest is shown to be an attractor in this case. The model coefficients and morphological time-scales derived from the cyclic experiments are very similar to those derived from the equilibrium experiments for the bulk transport. Normalised mean square model errors range from 1% to 20% when applied to independent data. The data from the cyclic wave conditions can be inverted to derive the conditions expected at equilibrium, which match those observed, indicating a robust model relationship between the forcing and P eq . The relationship between the forcing and P eq can also be determined directly from the cyclic experiments. This approach may be more robust than determining the relationship from periods where P is stationary since, in a time-series of P versus the forcing, stationary points can occur due to changes in wave conditions, in addition to the instances when P=P eq.

      PubDate: 2017-12-26T18:36:37Z
  • Assessing the impact of extreme storms on barrier beaches along the
           Atlantic coastline: Application to the southern Rhode Island coast
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Lauren Schambach, Annette R. Grilli, Stephan T. Grilli, M. Reza Hashemi, John W. King
      In this work, we use the 2D model XBeach to dynamically simulate coastal erosion due to a synthetic 100-year storm impacting a typical North Atlantic barrier beach located in southern RI. This storm was extracted from the North Atlantic Coast Comprehensive Study (NACCS) database, based on results of an extreme value analysis of more than 1000 NACCS storms. XBeach parameters are first calibrated/validated by simulating Hurricane Irene (August 2011), for which both nearshore wave data and pre- and post-storm beach profiles were available in the study area. Comparing results to observations allowed calibration of the wave asymmetry and skewness parameter ( γ u a = 0.3 ) in the model, resulting in a 6% mean relative error between the simulated and measured subaerial eroded volumes along 4 transects. In the 100-year storm XBeach simulations that include overwash, effects of land cover on beach erosion, in particular vegetation, are assessed by specifying a spatially varying bed friction function of high-resolution land cover. Results show that healthy back-dune vegetation is essential to prevent the dune crest from being fully eroded down to its toe level. The predicted median 100-year eroded volume is 46 m3/m for the entire barrier beach, in good agreement with FEMA's empirical value of 50 m3/m at the two “official 1D transects” within the study area; mean post-storm reductions in dune crest elevations are in similar agreement. The model, however, predicts very large alongshore variations of these parameters, with eroded volumes over 1000 m3/m where breaching and the opening of surge channels occurs. Overall, dune segmentation simulated in the model for the 100-year storm appears to be realistic and consistent with dune topography and land cover. XBeach thus provides an improved 2D methodology for assessing the impact of extreme storms on Atlantic barrier beaches, predicting changes in dune morphology, and quantifying the protective role of vegetation, and effects of land cover in general.

      PubDate: 2017-12-26T18:36:37Z
  • Prediction of current-induced local scour around complex piers: Review,
           revisit, and integration
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Danial Amini Baghbadorani, Behzad Ataie-Ashtiani, Aliasghar Beheshti, Mahmoud Hadjzaman, Mirmosadegh Jamali
      Complex piers (CPs), consisting of a column, pile cap and pile group, are commonly built as foundations for hydraulic and marine structures. Scour-hole development around CPs is studied in this paper. A total of 52 tests is carried out on 4 CP models, with experiments durations ranging from 24 to 120 h. All of the available experimental data for clear-water scour around CPs including the collected data of the present study and those previously published are reviewed and combined into a database. A special case of bridge piers with deep foundation or caisson instead of pile caps is also considered, which is herein called compound piers. The database contains 367 experiments for CPs and 162 experiments for compound piers. The predictive equations of the maximum scour-hole depth at complex piers including HEC-18 and FDOT equations are revisited and a new equation is proposed. Comparisons of the prediction equations shows that for CP data, the absolute error is 28%, 79% and 108% for the proposed, HEC-18 and FDOT equations, respectively. Underestimation below −20% error line occurs for 11%, 15%, and 7% of the cases in the proposed, HEC-18, and FDOT equations, respectively. For compound piers, the proposed equation has 41% absolute error while HEC-18 equation has 93% absolute error.

      PubDate: 2017-12-26T18:36:37Z
  • On the influence of wave directional spreading on the equilibrium planform
           of embayed beaches
    • Abstract: Publication date: March 2018
      Source:Coastal Engineering, Volume 133
      Author(s): Ahmed I. Elshinnawy, Raúl Medina, Mauricio González
      Equilibrium beach formulations are engineering tools for estimating a response of beaches in the long term. They aim at defining the final orientation of a beach on a scale of years and thus they are used for evaluating the shoreline response due to human interference (ports, breakwaters, protection works, etc). Several equations can be found in the literature for obtaining the Static Equilibrium Planform (SEP) of Headland Bay Beaches (HBBs), one such being the Parabolic Bay Shape Equation (PBSE). The SEP is strongly dependent on the location of the down-coast control point (Po) which is the downdrift limit from which the PBSE is applicable. The literature recommends the determination of the (Po) point by means of the direction of the mean wave energy flux at the diffraction point. However, when this is applied to equilibrium embayed beaches in zones with a wide variability of wave climate directionality and/or in cases where the diffraction point is located far from the equilibrium shoreline, this approach is no longer valid and thus the resulting planform shape does not properly fit the SEP for such conditions. This paper investigates the methodology for locating the (Po) point of the SEP for such cases, exploring the role of wave climate directional spreading, employing 44 HBBs in Spain and Latin America. It correlates the planform shape in the long term with the directional variability of the wave climate at the diffraction point. Additionally, an extensive series of numerical simulations using a spectral wave model was carried out to model the combined effects of refraction-diffraction in the lee of a breakwater, defining the part affected by the coastal structure under different wave conditions. The results clarify the importance of wave directional spreading in locating the (Po), indicating that the wider the directional spreading the farther the (Po) point on the shoreline. Moreover, the farther the diffraction point from the coast, the smaller the part of the beach affected by the coastal barrier. A new formula has been derived to locate the down-coast control point (Po) of the parabolic part of the shoreline corresponding to the PBSE as a function of the directional variance of the wave climate and the location of the diffraction point. The model produced good results with (R2 = 0.9117 and a RMSE = 1.8297°) in estimating the location of the (Po) point in various natural and man-made beaches with different degrees of wave directionality.

      PubDate: 2017-12-26T18:36:37Z
  • Breaking of ship bores in a Boussinesq-type ship-wake model
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Fengyan Shi, Matt Malej, Jane M. Smith, James T. Kirby
      A numerical study of ship-induced bores is carried out with a focus on soliton generation in different supercritical regimes, and the transition from breaking solitons to a pure bore measured in Gourlay's (2001) laboratory experiments. The fully nonlinear Boussinesq model, FUNWAVE-TVD, with appropriate dissipation schemes, is able to simulate ship-induced broken bores with amplitudes and periods consistent with the measured data. Two breaking dissipation schemes with different breaking criteria (a viscosity dissipation scheme with the surface slope breaking criterion, and a shock-capturing dissipation scheme with the wave height or surface elevation breaking criteria) are examined in a series of numerical experiments. It is found that both models predict soliton generation and the general trend of the transition from breaking solitons at lower Froude numbers to a pure bore at higher Froude numbers. Some differences are identified between the two different breaking schemes, including breaking locations, soliton propagation speed, amplitudes of wakes behind the ship, and the critical Froude number for the transition from a broken undular bore to a pure bore. In general, the viscosity-type breaker with the surface slope criterion performs more consistently with the laboratory observation compared with the shallow water equation-based shock-capturing breaker.

      PubDate: 2017-12-13T03:55:27Z
  • Model studies for flocculation of sand-clay mixtures
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Alan J.S. Cuthbertson, Farzin Samsami, Ping Dong
      Results are presented from a combined experimental and numerical study aimed at comparing the flocculation behaviour of purely-cohesive (clay) and mixed (sand-clay) sediment suspensions under equivalent controlled hydrodynamic conditions. The experiments were conducted in a grid-stirred settling column and focussed on measuring the parametric influences of grid-generated shear rate and local suspended sediment concentrations on the time-evolution of the micro- and macrofloc size distributions generated in the column, as well as representative maximal and root-mean-square floc sizes. The results indicate that for kaolin clay suspensions under low-medium shear rates, initial aggregation rates and the peak or quasi-equilibrium floc sizes attained increase with the clay input concentration; this latter effect due to the larger proportion of macroflocs generated within these runs. By contrast, under high shear rates, representative floc sizes for kaolin clay suspensions remain largely unchanged over the experimental duration, with little influence from clay input or in-situ concentrations, and no macroflocs present in the resulting floc size distributions. The addition of the fine sand fraction to the kaolin clay suspensions is shown to reduce both initial aggregation rates and the representative floc sizes attained in the column for runs under low-medium shear rates, whilst having negligible effect on the flocculation behaviour for the sand-clay mixtures under high shear rates. These results suggest that the sand fraction inhibits flocculation at lower shear rates due to an additional floc break-up mechanism resulting from direct sand-clay interactions (e.g. particle-floc collisions). The importance of these inter-fractional (sand-clay) interactions diminishes, in comparison to shear-induced floc break-up, under higher shear conditions. A one dimensional vertical (1DV) model incorporating a population balance equation (PBE) that includes new representation of these multi-fractional (sand-clay) collisions is applied to simulate the kaolin clay and sand-clay settling column tests. In general, the 1DV PBE model predictions provide good agreement with the measured in-situ concentrations and quasi-equilibrium floc sizes attained, but under-predict floc sizes during the initial aggregation phase due to uncertainty with the upper boundary condition in the 1DV model domain. Furthermore, the reliance of the 1DV PBE model predictions on empirical floc break-up rates associated with shear-induced floc fragmentation and multi-fractional (sand-clay) collisions warrants further attention to better define the microscale dynamics of these processes for their improved representation in the PBE model. It is anticipated that this multi-fractional approach represents an improved basis for modelling flocculation processes within natural sedimentary environments, such as estuaries and tidal inlets, where bed sediments often consist of interacting cohesive (i.e. muds) and non-cohesive (i.e. silts, sands) fractions.

      PubDate: 2017-12-13T03:55:27Z
  • Modelling of bed sediment composition changes at the lower shoreface of
           the Sand Motor
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): B.J.A. Huisman, B.G. Ruessink, M.A. de Schipper, A.P. Luijendijk, M.J.F. Stive
      Large perturbations in the coastline, such as the 'Sand Motor' nourishment ( ∼ 21 million m3) at the Holland coast, can initiate considerable spatial and temporal changes in the median grain size ( D 50 ) of the sea bed on the lower shoreface. The relevance of hydrodynamic conditions for the development of the heterogeneity in D 50 at large-scale nourishments was assessed with a numerical model (Delft3D), which required a validation against 2.5 years of D 50 measurements. A good representation of the observed spatial pattern of D 50 was obtained independent of a 2DH or 3D approach and initial condition for the D 50 of the bed. Five sediment size fractions and a multi-layer administration of the bed composition were used. The extent and magnitude of the coarsening of the bed is related to the velocity of the horizontal tide, while a far less pronounced coarsening takes place during energetic conditions (i.e. H m 0 ≥ 3 m). Differential suspension behaviour between the size fractions, which are all mobilized at the bed, causes a preferential transport of fine sediment (in alongshore direction) away from the Sand Motor at the lower shoreface (i.e. seaward of MSL -6 m). Storm conditions may induce a partial removal of the coarse top-layer due to mobilization of all of the size fractions and mixing with the relatively fine substrate material. Simulations also show that transport of the fine sand fraction extents to much deeper water than for the medium and coarse sand fractions. Models with multiple sediment fractions are therefore required for the assessment of environmental impacts of large-scale coastal structures or land reclamation's and sediment transport on the lower shoreface.

      PubDate: 2017-12-13T03:55:27Z
  • Estimations of wave forces on crown walls based on wave overtopping rates
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Jorge Molines, Maria P. Herrera, Josep R. Medina
      In this study, seven input variables are used to estimate wave forces on the crown wall, and explanatory variables are ranked using neural network techniques. 274 small-scale 2D tests, including both wave overtopping and pressure on crown-wall measurements, were used to calibrate the wave force predictors. Wave overtopping (log Q) was the most relevant variable to estimate horizontal wave forces and overturning moments, while the relative foundation level (F c /L 0p ) was the most relevant variable to estimate wave up-lift forces. The new wave force estimators showed prediction errors slightly higher than the formulas given in the literature, but using fewer parameters and explanatory variables. The range of application of the new formulas is 1.67 < R c /(γf H m0 ) < 6.55, 1.39 <  ξ 0p  < 7.77, 0.36 < γf R u0.1% /R c  < 1.41, 0.00 < (R c -A c )/C h  < 0.59, 2.64 <  L m / G c  < 6.54, 0.00 < F c /L 0p  < 0.03 and −6.00 < logQ < −2.78. Compared to pressure on crown walls, the mean wave overtopping rate is relatively easy to measure in small-scale tests and prototypes. The new estimators of wave forces on the crown wall can be used to indirectly calculate forces on models when only overtopping rates are measured. If wave overtopping is one order of magnitude higher, the wave forces and overturning moments on the crown wall increase between 11% and 60%, considerably reducing the crown wall stability.

      PubDate: 2017-12-13T03:55:27Z
  • Numerical modeling of salt marsh morphological change induced by Hurricane
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Kelin Hu, Qin Chen, Hongqing Wang, Ellen K. Hartig, Philip M. Orton
      The salt marshes of Jamaica Bay serve as a recreational outlet for New York City residents, mitigate wave impacts during coastal storms, and provide habitat for critical wildlife species. Hurricanes have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. In this study, the Delft3D modeling suite was utilized to examine the effects of Hurricane Sandy (2012) on salt marsh morphology in Jamaica Bay. Observed marsh elevation change and accretion from rod Surface Elevation Tables and feldspar Marker Horizons (SET-MH) and hydrodynamic measurements during Hurricane Sandy were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model. The model results agreed well with in situ field measurements. The validated model was then used to detect salt marsh morphological change due to Sandy across Jamaica Bay. Model results indicate that the island-wide morphological changes in the bay's salt marshes due to Sandy were in the range of −30 mm (erosion) to +15 mm (deposition), and spatially complex and heterogeneous. The storm generated paired deposition and erosion patches at local scales. Salt marshes inside the west section of the bay showed erosion overall while marshes inside the east section showed deposition from Sandy. The net sediment amount that Sandy brought into the bay is only about 1% of the total amount of reworked sediment within the bay during the storm. Numerical experiments show that waves and vegetation played a critical role in sediment transport and associated wetland morphological change in Jamaica Bay. Furthermore, without the protection of vegetation, the marsh islands of Jamaica Bay would experience both more erosion and less accretion in coastal storms.

      PubDate: 2017-12-13T03:55:27Z
  • The influence of bed friction variability due to land cover on
           storm-driven barrier island morphodynamics
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Davina L. Passeri, Joseph W. Long, Nathaniel G. Plant, Matthew V. Bilskie, Scott C. Hagen
      Variations in bed friction due to land cover type have the potential to influence morphologic change during storm events; the importance of these variations can be studied through numerical simulation and experimentation at locations with sufficient observational data to initialize realistic scenarios, evaluate model accuracy and guide interpretations. Two-dimensional in the horizontal plane (2DH) morphodynamic (XBeach) simulations were conducted to assess morphodynamic sensitivity to spatially varying bed friction at Dauphin Island, AL using hurricanes Ivan (2004) and Katrina (2005) as experimental test cases. For each storm, three bed friction scenarios were simulated: (1) a constant Chezy coefficient across land and water, (2) a constant Chezy coefficient across land and depth-dependent Chezy coefficients across water, and (3) spatially varying Chezy coefficients across land based on land use/land cover (LULC) data and depth-dependent Chezy coefficients across water. Modeled post-storm bed elevations were compared qualitatively and quantitatively with post-storm lidar data. Results showed that implementing spatially varying bed friction influenced the ability of XBeach to accurately simulate morphologic change during both storms. Accounting for frictional effects due to large-scale variations in vegetation and development reduced cross-barrier sediment transport and captured overwash and breaching more accurately. Model output from the spatially varying friction scenarios was used to examine the need for an existing sediment transport limiter, the influence of pre-storm topography and the effects of water level gradients on storm-driven morphodynamics.

      PubDate: 2017-12-13T03:55:27Z
  • The evolution of free and bound waves during dispersive focusing in a
           numerical and physical flume
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Thomas Vyzikas, Dimitris Stagonas, Eugeny Buldakov, Deborah Greaves
      Since the introduction of the NewWave theory (Lindgren, 1970), focused wave groups are used in physical and numerical studies to investigate the interaction of marine structures and ships with extreme waves. The propagation of such wave groups is associated with high order nonlinearities that can cause considerable deviations from linear and 2 n d order predictions. Consequently, nonlinear numerical models or laboratory tests are needed to accurately describe the evolution of focused wave groups. In the present study, we validate a widely used two-phase Reynolds Averaged Navier-Stokes (RANS) solver realised in OpenFOAM with experimental results for the propagation of steep focused wave groups, using a newly developed methodology based on the separation of harmonics. This approach allows for accurate focusing of wave groups and in-detail examination of the individual evolution of the high order terms, as well as identifying the source of discrepancies between experiments and numerical models. The wave groups comprise long-crested broadbanded Gaussian spectra of increasing steepness propagating in intermediate water depth. The contribution of the nonlinear harmonics to the crest height and overall shape of the wave are also discussed, together with the effect of nonlinear wave interactions on the free-wave spectrum. The rapid growth of 3 r d and 4 t h harmonics near focusing as well as the evolution of the free-wave spectrum, cause departures of up to 29% and 22% from analytic linear and 2 n d order predictions. The present results demonstrate that RANS-VoF solvers constitute accurate models to propagate nearly breaking waves.

      PubDate: 2017-12-13T03:55:27Z
  • Numerical modeling of wave runup on steep and mildly sloping natural
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Julia W. Fiedler, Pieter B. Smit, Katherine L. Brodie, Jesse McNinch, R.T. Guza
      Runup on ocean beaches includes steady wave setup and oscillating swash, often decomposed into wind generated sea-swell (SS), and lower frequency infragravity (IG) waves. We show that the numerically fast, open-source numerical model 1D SWASH predicts accurately the bulk properties of runup observed on two natural beaches (one steep and one shallow sloped) for a range of incident wave conditions. The runup tongue shape was measured with a scanning lidar, and the waterline location was defined in both the observations and model with a 10 cm depth threshold. Runup is reasonably accurately predicted with energetic (e.g. 5 m significant height) incident waves, even though the assumption of 1D bound waves significantly overpredicts infragravity energy at the offshore boundary in 10 m depth. The model-data comparisons are limited by statistical chatter, often larger in runup than offshore because runup energy is concentrated in the relatively narrow infragravity IG band with low effective degrees of freedom.

      PubDate: 2017-12-13T03:55:27Z
  • Distribution of turbulent eddies behind a monopile for vortex lock-on
           condition due to wave current combined flow
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Sayahnya Roy, Koustuv Debnath, Bijoy S. Mazumder
      The paper presents the results of an experimental study on wave current combined flow around a monopile (partially submerged circular cylinder) for a large Reynolds number. Measured instantaneous time series velocity signals (i.e., the sequence of discrete-time dependent velocity data) were analyzed to evaluate the statistical moments. It was found that vortex lock-on takes place when the forcing frequency of the superimposed surface wave is double that of the natural shedding (NS) frequency. Also, the recirculation region almost disappeared for vortex lock-on condition. The vortices generated due to superimposed surface waves increased the turbulence level near the shear layer at the recirculation region. Moreover, the Reynolds shear stress increased near the shear layer at the recirculation region due to vortex lock-on compared to that of NS condition. Further, the Gram-Charlier type joint probability distributions for two variables were estimated to describe the statistical properties of turbulent velocity fluctuations in different co-ordinate directions. Results from wavelet analysis of phased averaged velocity fluctuation suggested that the wave motion could modulate not only the large-scale eddies in the energy containing region, but the moderate scale eddies for the vortex lock-on condition. At the wake region of the monopile for vortex lock-on condition, it was pertinent that the wave motion induced fluctuating eddies of the background flow gained in strength and showed periodic distribution at the NS frequency (half of the induced wave frequency) in the time domain. The comparative study between NS and vortex lock-on condition showed that the induced wave motion can modulate the instantaneous small amplitude values of stream - wise and transverse velocity fluctuations ( u ' v ' ) that occur at the recirculation region.

      PubDate: 2017-11-16T14:06:32Z
  • A partial cell technique for modeling the morphological change and scour
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Zhong Peng, Qing-Ping Zou, Pengzhi Lin
      A novel partial cell technique applied on structured grids is developed to track the deformation of water-soil interface associated with beach morphological change and toe scour in front of coastal structures. It allows the use of the same orthogonal structured grids for morphological, sediment transport and hydrodynamic models therefore, has the advantage of consuming less CPU and without the need to adapt grids to the evolving beach morphology. An improved sand-slide model with better mass conservation is introduced to resolve the avalanche behaviour of the sediment motion. The RANS-VOF hydrodynamic model has been extended to cope with complex bathymetry. The newly developed numerical model suite, coupling the RANS-VOF model, a bedload sediment transport model and a morphological model using the partial cell technique, are validated against the analytical solutions and laboratory measurements for different incoming wave conditions, local water depths and bottom slopes. This study reveals the key processes that govern the behaviour of beach morphology change in front of a vertical coastal structure during storms. The model-data comparisons demonstrate the robustness of partial cell technique to capture the movement of the water-soil interface.

      PubDate: 2017-11-16T14:06:32Z
  • Drivers of alongshore variable dune erosion during a storm event:
           Observations and modelling
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Kristen D. Splinter, Edward T. Kearney, Ian L. Turner
      The ability to understand and predict alongshore-variable sand dune erosion is key to better coastal management. This study utilizes detailed observations (immediately pre, during and post-storm topography, waves and water levels) collected over a 6-day period at the 3.6 km long Narrabeen-Collaroy beach in south-east Australia, to identify and explore drivers of the highly variable alongshore dune erosion caused by an East Coast Low storm in June 2011. Key characteristics of the immediately pre-storm subaerial morphology obtained by airborne Lidar (beach slope, dune toe elevation, dune height) varied considerably alongshore. Daily airborne Lidar surveys conducted at low tide indicated considerable temporal variability in the evolution of the subaerial beach profile. Despite considerable alongshore variability in the magnitude of modelled inshore wave heights during the storm, it was instead observed that the predominant determinant of maximum dune erosion was the pre-storm dune toe elevation. A simple dune impact model forced with local alongshore-variable inshore wave modelling was found to successfully predict up to 85% of the observed alongshore variability in dune erosion at this site, with this erosion tidally modulated over the 6 days to time periods when the waves were directly impacting the dune. Importantly, alongshore variation in wave height is shown to account for just 10% of the alongshore variability in dune erosion during this storm. These results reconfirm that knowledge of the pre-storm subaerial morphology, in particular the elevation of the dune toe with respect to time-varying water levels during a storm, is a key driver of alongshore variability in the erosion response along dune-backed sandy coastlines.

      PubDate: 2017-11-08T13:15:07Z
  • Nonlinear and viscous effects on the hydrodynamic performance of a fixed
           OWC wave energy converter
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Rong-quan Wang, De-zhi Ning, Chong-wei Zhang, Qing-ping Zou, Zhen Liu
      The hydrodynamic performance of a fixed Oscillating Water Column (OWC) device is experimentally and numerically investigated. Based on the time-domain higher-order boundary element method (HOBEM), by introducing an artificial viscosity term in the dynamic free surface boundary condition, a fully nonlinear numerical wave model is used to simulate the hydrodynamic performance of an OWC device. A set of comprehensive experiments for regular waves is carried out to validate the numerical results as well as to investigate the nonlinear effects on the hydrodynamic performance of OWC. The mechanism of the nonlinear phenomenon is investigated based on the analysis of the experimental and numerical results. The influence of the wave nonlinearity and the viscosity on the hydrodynamic efficiency is quantified by comparing the linear and nonlinear numerical results. It was found that the hydrodynamic efficiency increases with the nonlinearity and viscosity when the incident wave amplitude is small. When the incident wave amplitude is large, the hydrodynamic efficiency is reduced by the weakened transmission of the second-order harmonic wave component due to the strong wave nonlinearity. However, when the wave amplitude is between these two regimes, the wave is weakly nonlinear, the efficiency decreases with the wave amplitude due to the combined effect of the nonlinearity and viscosity.

      PubDate: 2017-11-08T13:15:07Z
  • Numerical modelling of erosion rates, life span and maintenance volumes of
           mega nourishments
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): P.K. Tonnon, B.J.A. Huisman, G.N. Stam, L.C. van Rijn
      Mega-nourishments, aiming at providing long-term coastal safety, nature qualities and recreational space, have been applied recently at the Holland coast and are considered at various other places in the world. Methods to quickly evaluate the potential and lifetime of these coastal mega nourishments are therefore very much desired, which is the main objective of this research. Two types of mega nourishments can be distinguished: feeder-type mega nourishments may erode freely to feed adjacent coasts for a more natural, dynamic dune growth while permanent mega-nourishments are designed to preserve safety levels and need to maintain their size and shape and thus needs to be nourished themselves. The design and impact assessment studies for both types of mega nourishments require detailed morphological studies to determine the morphological evolution. In this paper 2DH (Delft3D) and 1D (UNIBEST-CL+ and LONGMOR) numerical models were calibrated using data of the Sand Motor mega-nourishment and were then applied to model a series of mega-nourishments with various width over length ratios and volumes in order to derive relations and design graphs for erosion rates, life span and maintenance volumes. These relations and design graphs can be used in project initiation phases and feasibility studies. The magnitude of the modelled wave-driven longshore sediment transport rates in 1D coastline models depend on the representation of wave refraction on the lower shoreface, since a distinction should be made between the non-rotating lower shoreface and active surfzone. It was shown that the life time of nourishments is mainly determined by the dimensions of the nourishment and incoming wave energy.

      PubDate: 2017-11-08T13:15:07Z
  • Comparison of a mid-shelf wave hindcast to ADCP-measured directional
           spectra and their transformation to shallow water
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): William R. Dally
      In conducting a cross-shelf wave transformation experiment off the Atlantic coast of north Florida, a unique opportunity was exploited in which an Acoustic Doppler Current Profiler (ADCP) instrument was installed 30 km offshore at the exact location of one of the archive-nodes of a WAM-like wave hindcast model (OWI3G). A second ADCP was installed 550 m from shore. Approximately 53 days of directional wave spectra collected with the two ADCPs are used to (a) locally test the reliability of a subsequent update of the hindcast, (b) document the loss in energy as the waves crossed the broad, relatively shallow continental shelf between the two instruments, (c) test the ability of the SWAN (Gen2) nearshore wave transformation model to replicate the measurements taken in shallow water when driven by the offshore ADCP spectra, and (d) reassess the spectral transformation results when the offshore hindcast is used as input. In addition to direct comparison of the time series of frequency spectra and the directional distribution of energy, typical spectral parameters are each subjected to standard error tests. Results indicate that the offshore hindcast performs well in replicating significant wave height, fairly well for mean period, but not as reliably for peak period. Directional spreading in deeper water is generally well-represented, although vector mean direction is not, and is believed due to the proximity of the coast to the hindcast node. The nearshore model requires an order-of-magnitude reduction in bed roughness from its default value before agreement in wave energy at the nearshore ADCP can be achieved. Outcomes of the error tests for the hindcast-driven versus the ADCP-driven nearshore results (after roughness calibration) are quite similar, but nevertheless indicate that transformed wave period, wave direction, and directional spreading require improvement.

      PubDate: 2017-11-02T13:01:13Z
  • On the splash-up of tsunami bore impact
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Harrison T.-S. Ko, Harry Yeh
      Impulsive forces on a box-shaped structure due to bore impact are investigated experimentally. Experiments are conducted in the laboratory by generating a Gaussian-shaped wave onto a step before impacting structures of three different cross-shore to long-shore length ratios. The relationship between measurements of the splash-up flow on the structure wall and the force measurements is investigated. The pressures are predicted based on the Euler model. Maximum impact forces are found to occur during the run-down phase after the maximum splash-up value is reached. The uniform vertical velocity profile assumption used in the Euler model yields a better estimate for the impact force than the linear and hydrostatic assumptions. In order to verify the pressure distribution during the splash-up flow, we utilize the pressure data collected from a separate experiment in a large-scale laboratory flume. The combined evidence suggests that the flow near the splash-up tip behaves like a solid body projectile.

      PubDate: 2017-10-26T01:22:28Z
  • Effects of dual wavenumber dispersion solutions on a nonlinear
           monochromatic wave-current field
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): David M. Kouskoulas, Yaron Toledo
      An analytical solution for quadratic nonlinear wave-current interactions is derived using a perturbation method. In contrast to existing formulations, it accounts for dual wavenumber solutions of the linear problem for a single frequency and their nonlinear interactions. It is demonstrated that even a small amount of energy present on the second solution will introduce significant quantitative and qualitative differences in the surface elevation. These differences include a shorter wavelength component moving with a lower wave celerity, nonlinear spatial focusing, and a mean water level that varies in space. The second solution is also shown to produce a mechanism which may easily result in localized violations of wave breaking criteria. These weakly nonlinear effects are expected to be relevant to a variety of engineering applications and physical processes.

      PubDate: 2017-10-11T13:05:36Z
  • Lagoon water-level oscillations driven by rainfall and wave climate
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): R. González-Villanueva, M. Pérez-Arlucea, S. Costas
      Barrier breaching and subsequent inlet formation represent critical processes that ensure the temporary or permanent connection and transference of water, nutrients, or living organisms between a lagoon and the open sea. Here, we investigate the conditions inducing natural barrier breaching through a 34 months monitoring program of water-level oscillations within a shallow lagoon and the adjacent nearshore, at the Northern coast of the Iberian Peninsula, Louro lagoon. Seven natural openings were identified to have occurred during the three monitored wet seasons, from the 2009 to 2012, (Wet1, Wet2 and Wet3); four in the Wet1, two in the Wet2 and one in the Wet3. The openings were grouped in three types depending on the observed relation between the lagoon water-level (Lwl), the estimated berm height (Bh) and the water-level at the beach (Bwl): (i) openings by lagoon outflow, which include those characterized by Lwl higher than Bh and lower Bwl; (ii) openings by wave inundation, including those induced by Bwl higher than Bh, and (iii) mixed openings, which result from a combination of the two previous conditions. We observed that Lwl is modulated by the rainfall regime (Rf) and can be explained by the accumulated precipitation. We estimated applying runup equations to obtain Bh and Bwl which depend on the wave climate and tidal level. The inlet lifespan was found to be regulated by the wave climate and rainfall regime; in particular barrier sealing was associated with a sudden increase in wave period and a reduction in precipitation. This work proves that the natural openings could be predicted successfully with support to medium term water-level monitoring programs, which in turn may significantly contribute to strategic decision making for management and conservation purposes.

      PubDate: 2017-10-11T13:05:36Z
  • Wave runup video motion detection using the Radon Transform
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Rafael Almar, Chris Blenkinsopp, Luis Pedro Almeida, Rodrigo Cienfuegos, Patricio A. Catalán
      A new method of runup detection from video imagery is introduced and validated at an energetic dissipative beach. The instantaneous waterline is detected from uprush and backwash by using the Radon Transform (RT). The method is compared to conventional color contrast method from RGB images and LiDAR measurements. In our observations, the RT shows better detection skill even for adverse conditions, such as those present on flat dissipative swash zones where contrast is reduced. Because the RT is a proxy of deeper waterline (∼0.1 m) it is less sensitive to lack of contrast due to sand saturation. Moreover, since it is based on motion detection, it is less sensitive to changes in lighting conditions. Overall, the RT offers an attractive alternative for long term automated detection of the runup.

      PubDate: 2017-10-11T13:05:36Z
  • A simplified physically-based model for coastal dike and barrier breaching
           by overtopping flow and waves
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Weiming Wu, Honghai Li
      The simplified physically-based breach model, DLBreach, has been developed to simulate the overtopping breaching of coastal dikes and barriers, which can occur either from the sea side or the bay side. The breaching process is divided into two stages: intensive breaching and general inlet evolution, in which the flows are calculated using the weir flow equation and the Keulegan equation, respectively. The Keulegan equation is a simplified energy equation for steady nonuniform flow with local head loss due to channel contraction and expansion, revised herein by adding the wind driving force. Empirical formulas are adopted to calculate phase-averaged wave overtopping discharge, wave setup, and wind setup/setdown. The wave overtopping discharge is combined with the surge overflow discharge, and the wave setup and wind setup/setdown are added to the sea and bay water levels for the hydrodynamic and sediment routing. Alongshore sediment is considered as a source boundary condition for the non-equilibrium sediment transport model at the breach. The model has been tested using the 94’ field experiment of sea dike breaching by overflow in the Zwin Channel Estuary, a laboratory experiment of sea dike breaching initiated by wave overtopping, and a field observation of the eight-day breaching and closure event of the Mecox Inlet at eastern Long Island of New York during Sept. 10–18, 1985. The model results agree generally well with the measurements.

      PubDate: 2017-10-03T12:30:24Z
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