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Earth and Planetary Sciences › Earth-Surface Processes

Coastal and Marine Dynamics

Works Count: 76313

Description

This cluster of papers encompasses a wide range of topics related to coastal dynamics, including sea-level rise, shoreline change, wave modeling, coastal vulnerability, beach erosion, sediment transport, climate change impacts, coastal management, and remote sensing techniques. The papers collectively aim to understand and address the complex interactions between natural processes and human activities in coastal environments.

Keywords

Coastal Dynamics; Sea-Level Rise; Shoreline Change; Wave Modeling; Coastal Vulnerability; Beach Erosion; Sediment Transport; Climate Change Impacts; Coastal Management; Remote Sensing

Sea-Level Rise as a Cause of Shore Erosion

1962-02-01
Per Bruun
It is established fact that sea level is rising slowly and irregularly; also, it seems to be true that erosion on most seashores built up of alluvial materials greatly exceeds … It is established fact that sea level is rising slowly and irregularly; also, it seems to be true that erosion on most seashores built up of alluvial materials greatly exceeds accretion; relationship between rise of sea level and erosion.

Storm Impact Scale for Barrier Islands

2000-07-28
Jr. Asbury H. Sallenger
A new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms. The proposed scale is fundamentally different than existing storm-related scales in that … A new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms. The proposed scale is fundamentally different than existing storm-related scales in that the coupling between forcing processes and the geometry of the coast is explicitly included. Four regimes, representing different levels of impact, are defined. Within each regime, patterns and relative magnitudes of net erosion and accretion are argued to be unique. The borders between regimes represent thresholds defining where processes and magnitudes of impacts change dramatically. Impact level 1 is the 'swash' regime describing a storm where runup is confined to the foreshore. The foreshore typically erodes during the storm and recovers following the storm; hence, there is no net change. Impact level 2 is the 'collision' regime describing a storm where the wave runup exceeds the threshold of the base of the foredune ridge. Swash impacts the dune forcing net erosion. Impact level 3 is the 'overwash' regime describing a storm where wave runup overtops the berm or, if present, the foredune ridge. The associated net landward sand transport contributes to net migration of the barrier landward. Impact level 4 is the 'inundation' regime describing a storm where the storm surge is sufficient to completely and continuously submerge the barrier island. Sand undergoes net landward transport over the barrier island; limited evidence suggests the quantities and distance of transport are much greater than what occurs during the 'overwash' regime.

Biology and the Mechanics of the Wave-Swept Environment

1988-12-31
Mark Denny
This text introduces and draws together pertinent aspects of fluid dynamics, physical oceanography, solid mechanics, and organismal biology to provide a much-needed set of tools for quantitatively examining the biological … This text introduces and draws together pertinent aspects of fluid dynamics, physical oceanography, solid mechanics, and organismal biology to provide a much-needed set of tools for quantitatively examining the biological effects of ocean waves. "Nowhere on earth does water move as violently as on wave-swept coasts," writes the author, "and every breaker that comes pounding on the shore places large hydrodynamic forces on the organisms resident there." Yet wave-swept coral reefs and rocky shores are home to some of the world's most diverse assemblages of plants and animals, and scientists have chosen these environments to carry out much of the recent experimental work in community structure and population dynamics. Until now these studies have been hampered because biologists often lack a working understanding of the mechanics of the wave-swept shore. Mark Denny here supplies that understanding in clear and vivid language. Included are an introduction to wave-induced water motions and the standard theories for describing them, a broad introduction to the hydrodynamic forces these water movements place on plants and animals, and an explanation of how organisms respond to these forces. These tools are put to use in the final chapters in an examination of the mechanisms of "wave exposure" and an exploration of the mechanical determinants of size and shape in wave-swept environments. Originally published in 1988. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

ENERGY LOSS AND SET-UP DUE TO BREAKING OF RANDOM WAVES

1978-01-29
J.A. Battjes , J. P. F. M. Janssen
A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach. The dissipation rate per breaking wave is … A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach. The dissipation rate per breaking wave is estimated from that in a bore of corresponding height, while the probability of occurrence of breaking waves is estimated on the basis of a wave height distribution with an upper cut-off which in shallow water is determined mainly by the local depth. A comparison with measurements of wave height decay and set-up, on a plane beach and on a beach with a bar-trough profile, indicates that the model is capable of predicting qualitatively and quantitatively all the main features of the data.
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Coastal Bottom Boundary Layers and Sediment Transport

1992-07-01
Peter Nielsen
This book is intended as a useful handbook for professionals and researchers in the areas of Physical Oceanography, Marine Geology, Coastal Geomorphology and Coastal Engineering and as a text for … This book is intended as a useful handbook for professionals and researchers in the areas of Physical Oceanography, Marine Geology, Coastal Geomorphology and Coastal Engineering and as a text for graduate students in these fields. With its emphasis on boundary layer flow and basic sediment transport modelling, it is meant to help fill the gap between general hydrodynamic texts and descriptive texts on marine and coastal sedimentary processes. The book commences with a review of coastal bottom boundary layer flows including the boundary layer interaction between waves and steady currents. The concept of eddy viscosity for these flows is discussed in depth because of its relation to sediment diffusivity. The quasi-steady processes of sediment transport over flat beds are discussed. Small scale coastal bedforms and the corresponding hydraulic roughness are described. The motion of suspended sand particles is studied in detail with emphasis on the possible suspension maintaining mechanisms in coastal flows. Sediment pickup functions are provided for unsteady flows. A new combined convection-diffusion model is provided for suspended sediment distributions. Different methods of sediment transport model building are presented together with some classical models.

Energy Loss and Set-Up Due to Breaking of Random Waves

1978-08-27
J.A. Battjes , J. P. F. M. Janssen
A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach. The dissipation rate per breaking wave is … A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach. The dissipation rate per breaking wave is estimated from that in a bore of corresponding height, while the probability of occurrence of breaking waves is estimated on the basis of a wave height distribution with an upper cut-off which in shallow water is determined mainly by the local depth. A comparison with measurements of wave height decay and set-up, on a plane beach and on a beach with a bar-trough profile, indicates that the model is capable of predicting qualitatively and quantitatively all the main features of the data.
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Handbook of beach and shoreface morphodynamics

1999-01-01
Andrew D. Short
BEACH SYSTEMS: DEFINITION AND GLOBAL PERSPECTIVE. Beaches (A. Short). Global Variation in Beach Systems (A. Short). BEACH MORPHODYNAMICS. The Shoreface (P. Cowell, et al.). The Surf Zone (T. Aagaard & … BEACH SYSTEMS: DEFINITION AND GLOBAL PERSPECTIVE. Beaches (A. Short). Global Variation in Beach Systems (A. Short). BEACH MORPHODYNAMICS. The Shoreface (P. Cowell, et al.). The Surf Zone (T. Aagaard & G. Masselink). The Beachface (M. Hughes & I. Turner) The Beach Backshore and Beyond (P. Hesp). BEACH TYPES AND APPLICATIONS. Wave--Dominated Beaches (A. Short). The Effect of Tides on Beach Morphodynamics (G. Masselink & I. Turner). Embayed and Structurally Controlled Beaches (A. Short & G. Masselink). BEACH SYSTEMS AND IMPACTS. Beach Modification: Natural Impacts on Beach Morphodynamics (A. Short). Beach Ecology (A. Short & P. Hesp). Beach and Dune Stratification (A. Short & P. Hesp). Beach Hazards and Safety (A. Short). LARGE SCALE BEACH BEHAVIOUR. Barrier Morphodynamics (P. Hesp & A. Short). References. Indexes.

Equilibrium Beach Profiles: Characteristics and Applications

1991-01-29
Robert G. Dean
An understanding of equilibrium beach profiles can be useful in a number of types of coastal engineering projects. Empirical correlations between a scale parameter and the sediment size or fall … An understanding of equilibrium beach profiles can be useful in a number of types of coastal engineering projects. Empirical correlations between a scale parameter and the sediment size or fall velocity allow computation of equilibrium beach profiles. The most often used form is h(y) = Ay 2/3 in which h is the water depth at a distance y from the shoreline and A is the sediment-dependent scale parameter. Expressions for shoreline position change are presented for arbitrary water levels and wave heights. Application of equilibrium beach profile concepts to profile changes seaward of a seawall include effects of sea level change and arbitrary wave heights. For fixed wave heights and increasing water level, the additional depth adjacent to the seawall first increases, then decreases to zero for a wave height just breaking at the seawall. Shoreline recession and implications due to increased sea level and wave heights are examined. It is shown, for the equilibrium profile form examined, that the effect of wave set-up on recession is small compared to expected storm tides during storms. Profile evolution from a uniform slope is shown to result in five different profile types, depending on initial slope, sediment characteristics, berm height and depth of active sediment redistribution. The reduction in required sand volumes through perching of a nourished beach by an offshore sill is examined for arbitrary sediment and sill combinations. When beaches are nourished with a sediment of arbitrary but uniform size, it is found that three types of profiles can result: (1) submerged profiles in which the placed sediment is of smaller diameter than the native and all of the sediment equilibrates underwater with no widening of the dry beach, (2) non-intersecting profiles in which the sea- ward portion of the placed material lies above the original profile at that location, and (3) intersecting profiles with the placed sand coarser than the native and resulting in the placed profile intersecting with the original profile. Equations and graphs are presented portraying the additional dry beach width for differing volumes of sand of varying sizes relative to the native. The offshore volumetric redistribution of material due to sea level rise as a function of water depth is of interest in interpreting the cause of shoreline recession. If only offshore transport occurs and the surveys extend over the active profile, the net volumetric change is zero. It is shown that the maximum volume change due to cross-shore sediment redistribution is only a fraction of the product of the active vertical profile dimension and shoreline recession. The paper presents several other applications of equilibrium beach profiles to problems of coastal engineering interest.

The Effect of Tide Range on Beach Morphodynamics and Morphology: A Conceptual Beach Model

1993-07-10
Gerd Masselink , Andrew D. Short
Natural beaches may be grouped into several beach types on the basis of breaker height (H b ), wave period (T), high tide sediment fall velocity (w s ) and … Natural beaches may be grouped into several beach types on the basis of breaker height (H b ), wave period (T), high tide sediment fall velocity (w s ) and tide range (TR). These four variables are quantified by two dimensionless parameters: the dimensionless fall velocity (Ω= H b /w s T) used by WRIGHT and SHORT (1984) to classify micro-tidal beaches, and the relative tide range (RTR = TR/H b ) introduced in this paper. The value of the dimensionless fall velocity indicates whether reflective, intermediate or dissipative surf zone conditions will prevail. The relative tide range reflects the relative importance of swash, surf zone and shoaling wave processes. A conceptual model is presented in which beach morphology (beach type) may be predicted using the dimensionless fall velocity and the relative tide range, whereby the mean spring tide range (MSR) is used to calculate the relative tide range. The model consists of the existing micro-tidal beach types, which as RTR Increases, shift from reflective to low tide terrace with and finally without rips; from intermediate to low tide bar and rips and finally ultra-dissipative; and from barred dissipative to non-barred dissipative and finally ultra-dissipative. Using this model, all wave-dominated beaches in all tidal ranges can be classified.

Coastal and estuarine sediment dynamics

1987-05-01
Peter Sonnenfeld

A wave generation toolbox for the open‐source CFD library: OpenFoam®

2011-11-28
Niels G. Jacobsen , David R. Fuhrman , Jørgen Fredsøe
SUMMARY The open‐source CFD library OpenFoam® contains a method for solving free surface Newtonian flows using the Reynolds averaged Navier–Stokes equations coupled with a volume of fluid method. In this … SUMMARY The open‐source CFD library OpenFoam® contains a method for solving free surface Newtonian flows using the Reynolds averaged Navier–Stokes equations coupled with a volume of fluid method. In this paper, it is demonstrated how this has been extended with a generic wave generation and absorption method termed ‘wave relaxation zones’, on which a detailed account is given. The ability to use OpenFoam for the modelling of waves is demonstrated using two benchmark test cases, which show the ability to model wave propagation and wave breaking. Furthermore, the reflection coefficient from outlet relaxation zones is considered for a range of parameters. The toolbox is implemented in C++, and the flexibility in deriving new relaxation methods and implementing new wave theories along with other shapes of the relaxation zone is outlined. Subsequent to the publication of this paper, the toolbox has been made freely available through the OpenFoam‐Extend Community. Copyright © 2011 John Wiley & Sons, Ltd.

Mechanics of Coastal Sediment Transport

1992-11-01
Jørgen Fredsøe , Rolf Deigaard
The main objective of the book is to describe from a deterministic point of view the sediment transport in the general wave-current situation. For this purpose, the book is divided … The main objective of the book is to describe from a deterministic point of view the sediment transport in the general wave-current situation. For this purpose, the book is divided into two major parts. The first part of the book is related to flow and turbulence in combined wave-current. This part covers the turbulent wave boundary layer, bed friction in combined wave-current motion, turbulence in the surf zone, and wave-driven currents in the long- and cross-shore direction. The second part treats the sediment transport as a result of the wave-current action. This part includes an introduction to basic sediment transport concepts, distribution of suspended sediment in the sheet flow regime, description of bedforms formed by current and waves, and their influence on sediment transport pattern. Finally, the modelling of cross- and long-shore sediment transport is described. This book is useful for students with a background in basic hydrodynamics.

Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding - A Global Assessment

2015-03-11
Barbara Neumann , Athanasios T. Vafeidis , Juliane Zimmermann +1 more
Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and … Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we identify needs for further research and scope for improvement in this kind of scenario-based exposure analysis.
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Long waves on a beach

1967-03-20
D. H. Peregrine
Equations of motion are derived for long waves in water of varying depth. The equations are for small amplitude waves, but do include non-linear terms. They correspond to the Boussinesq … Equations of motion are derived for long waves in water of varying depth. The equations are for small amplitude waves, but do include non-linear terms. They correspond to the Boussinesq equations for water of constant depth. Solutions have been calculated numerically for a solitary wave on a beach of uniform slope. These solutions include a reflected wave, which is also derived analytically by using the linearized long-wave equations.

Empirical parameterization of setup, swash, and runup

2006-02-22
Hilary F. Stockdon , R. A. Holman , Peter A. Howd +1 more

Alternative Form of Boussinesq Equations for Nearshore Wave Propagation

1993-11-01
Okey Nwogu
Boussinesq‐type equations can be used to model the nonlinear transformation of surface waves in shallow water due to the effects of shoaling, refraction, diffraction, and reflection. Different linear dispersion relations … Boussinesq‐type equations can be used to model the nonlinear transformation of surface waves in shallow water due to the effects of shoaling, refraction, diffraction, and reflection. Different linear dispersion relations can be obtained by expressing the equations in different velocity variables. In this paper, a new form of the Boussinesq equations is derived using the velocity at an arbitrary distance from the still water level as the velocity variable instead of the commonly used depth‐averaged velocity. This significantly improves the linear dispersion properties of the Boussinesq equations, making them applicable to a wider range of water depths. A finite difference method is used to solve the equations. Numerical and experimental results are compared for the propagation of regular and irregular waves on a constant slope beach. The results demonstrate that the new form of the equations can reasonably simulate several nonlinear effects that occur in the shoaling of surface waves from deep to shallow water including the amplification of the forced lower‐ and higher‐frequency wave harmonics and the associated increase in the horizontal and vertical asymmetry of the waves.

An energetics total load sediment transport model for a plane sloping beach

1981-11-20
James A. Bailard
Bagnold's energetics‐based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane … Bagnold's energetics‐based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane sloping bed. In both the bedload and suspended load, the transport rate vectors are found to be composed of a velocity‐induced component directed parallel to the instantaneous velocity vector and a gravity‐induced component directed down slope. The model is applied to idealized surfzone conditions, leading to estimates of the local longshore and onshore‐offshore sediment transport rates as well as the equilibrium beach slope as a function of the local wave and current conditions. The model is combined with a nonlinear longshore current model and spatially integrated to obtain predictions of the total longshore transport rate as a function of the incident wave conditions. The results support the general form of the wave power equation except that the wave power coefficient is no longer constant but is instead a complex function of the incident wave and beach characteristics.

Effective sea-level rise and deltas: Causes of change and human dimension implications

2006-01-27
Jason P. Ericson , Charles Vörösmarty , Stephen Dingman +2 more

A new form of the Boussinesq equations with improved linear dispersion characteristics. Part 2. A slowly-varying bathymetry

1992-12-01
Per A. Madsen , Ole R. Sørensen

A numerical study of breaking waves in the surf zone

1998-03-25
Pengzhi Lin , Philip L.‐F. Liu
This paper describes the development of a numerical model for studying the evolution of a wave train, shoaling and breaking in the surf zone. The model solves the Reynolds equations … This paper describes the development of a numerical model for studying the evolution of a wave train, shoaling and breaking in the surf zone. The model solves the Reynolds equations for the mean (ensemble average) flow field and the k –ε equations for the turbulent kinetic energy, k , and the turbulence dissipation rate, ε. A nonlinear Reynolds stress model (Shih, Zhu & Lumley 1996) is employed to relate the Reynolds stresses and the strain rates of the mean flow. To track free-surface movements, the volume of fluid (VOF) method is employed. To ensure the accuracy of each component of the numerical model, several steps have been taken to verify numerical solutions with either analytical solutions or experimental data. For non-breaking waves, very accurate results are obtained for a solitary wave propagating over a long distance in a constant depth. Good agreement between numerical results and experimental data has also been observed for shoaling and breaking cnoidal waves on a sloping beach in terms of free-surface profiles, mean velocities, and turbulent kinetic energy. Based on the numerical results, turbulence transport mechanisms under breaking waves are discussed.

Combined wave and current interaction with a rough bottom

1979-04-20
William D. Grant , Ole Secher Madsen
An analytical theory is presented to describe the combined motion of waves and currents in the vicinity of a rough bottom and the associated boundary shear stress. Characteristic shear velocities … An analytical theory is presented to describe the combined motion of waves and currents in the vicinity of a rough bottom and the associated boundary shear stress. Characteristic shear velocities are defined for the respective wave and current boundary layer regions by using a combined wave‐current friction factor, and turbulent closure is accomplished by employing a time invariant turbulent eddy viscosity model which increases linearly with height above the seabed. The resulting linearized governing equations are solved for the wave and current kinematics both inside and outside the wave boundary layer region. For the current velocity profile above the wave boundary layer, the concept of an apparent bottom roughness is introduced, which depends on the physical bottom roughness as well as the wave characteristics. The net result is that the current above the wave boundary layer feels a larger resistance due to the presence of the wave. The wave‐current friction factor and the apparent roughness are found as a function of the velocity of the current relative to the wave orbital velocity, the relative bottom roughness, and the angle between the currents and the waves. In the limiting case of a pure wave motion the predictions of the velocity profile and wave friction factor from the theory have been shown to give good agreement with experimental results. The reasonable nature of the concept of the apparent bottom roughness is demonstrated by comparison with field observations of very large bottom roughnesses by previous investigators. The implications of the behavior predicted by the model on sediment transport and shelf circulation models are discussed.

Non-linear tidal distortion in shallow well-mixed estuaries: a synthesis

1988-11-01
Carl T. Friedrichs , David G. Aubrey

Global Warming and Coastal Erosion

2004-04-21
Keqi Zhang , Bruce C. Douglas , Stephen P. Leatherman

Morphodynamic variability of surf zones and beaches: A synthesis

1984-04-01
L. D. Wright , Andrew D. Short

SWASH: An operational public domain code for simulating wave fields and rapidly varied flows in coastal waters

2011-07-05
Marcel Zijlema , Guus S. Stelling , Pieter Smit

Boussinesq Modeling of Wave Transformation, Breaking, and Runup. I: 1D

2000-01-01
Andrew B. Kennedy , Qin Chen , James T. Kirby +1 more
Parts I and II of this paper describe the extension and testing of two sets of Boussinesq-type equations to include surf zone phenomena. Part I is restricted to 1D tests … Parts I and II of this paper describe the extension and testing of two sets of Boussinesq-type equations to include surf zone phenomena. Part I is restricted to 1D tests of shoaling, breaking, and runup, while Part II deals with two horizontal dimensions. The model uses two main extensions to the Boussinesq equations: a momentum-conserving eddy viscosity technique to model breaking, and a “slotted beach,” which simulates a shoreline while allowing computations over a regular domain. Bottom friction is included, using a quadratic representation, while the 2D implementation of the model also considers subgrid mixing. Comparisons with experimental results for regular and irregular wave shoaling, breaking and runup for both one and two horizontal dimensions show good agreement for a variety of wave conditions.

A new form of the Boussinesq equations with improved linear dispersion characteristics

1991-07-01
Per A. Madsen , Russel Murray , Ole R. Sørensen

Transformation of wave height distribution

1983-07-20
Edward B. Thornton , R. T. Guza
The transformation of random wave heights during shoaling, including waves breaking in the surf zone, was measured with an extensive array of instruments in the field. The initially Rayleigh height … The transformation of random wave heights during shoaling, including waves breaking in the surf zone, was measured with an extensive array of instruments in the field. The initially Rayleigh height distributions in 10‐m depth were observed to be modified by shoaling and breaking into new distributions which are again nearly Rayleigh but with some energy loss. Using locally measured H rms , the Rayleigh distribution describes the measured central moments of H 1/3 and H 1/10 with average errors of −0.2% and −1.8%, respectively. The Rayleigh distribution is used to describe the random nature of wave heights in a single‐parameter transformation model based on energy flux balance. The energy losses associated with wave breaking are parameterized using observed breaking wave distributions coupled with a periodic bore dissipation model. Using incident waves measured in 10‐m depth as input conditions, the model predicts H rms at shoreward locations within a rms error of ±9%. The single free parameter of the model, a constant B representing the fraction of foam on the face of a wave, was chosen to best fit the data. The resulting large value of B implies that the simple periodic bore dissipation function substantially underestimates the actual dissipation.

Longshore currents generated by obliquely incident sea waves: 1

1970-11-20
M. S. Longuet‐Higgins
By using known results on the radiation stress associated with gravity waves, the total lateral thrust exerted by incoming waves on the beach and in the nearshore zone is rigorously … By using known results on the radiation stress associated with gravity waves, the total lateral thrust exerted by incoming waves on the beach and in the nearshore zone is rigorously shown to equal (E0/4) sin 2θ0 per unit distance parallel to the coastline, where E0 denotes the energy density of the waves in deep water and θ0 denotes the waves' angle of incidence. The local stress exerted on the surf zone in steady conditions is shown to be given by (D/c) sin θ per unit area, where D is the local rate of energy dissipation and c is the phase velocity. These relations are independent of the manner of the energy dissipation, but, because breaker height is related to local depth in shallow water, it is argued that ordinarily most of the dissipation is due to wave breaking, not to bottom friction. Under these conditions the local mean longshore stress in the surf zone will be given by (5/4)ρumax2 s sin θ, where ρ is the density, umax is the maximum orbital velocity in the waves, s is the local beach slope, and θ is the angle of incidence. It is further shown that, if the friction coefficient C on the bottom is assumed constant and if horizontal mixing is neglected, the mean longshore component of velocity is given by (5π/8)(s/C) umax sin θ. This value is proportional to the longshore component of the orbital velocity. When the horizontal mixing is taken into account, the longshore currents observed in field observations and laboratory experiments are consistent with a friction coefficient of about 0.010.

The paradox of drowned reefs and carbonate platforms

1981-01-01
Wolfgang Schlager
Research Article| April 01, 1981 The paradox of drowned reefs and carbonate platforms WOLFGANG SCHLAGER WOLFGANG SCHLAGER 1Comparative Sedimentology Laboratory, Rosenstiel School of Marine and Atmospheric Science, University of Miami, … Research Article| April 01, 1981 The paradox of drowned reefs and carbonate platforms WOLFGANG SCHLAGER WOLFGANG SCHLAGER 1Comparative Sedimentology Laboratory, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Fisher Island Station, Miami, Florida 33139 Search for other works by this author on: GSW Google Scholar Author and Article Information WOLFGANG SCHLAGER 1Comparative Sedimentology Laboratory, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Fisher Island Station, Miami, Florida 33139 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1981) 92 (4): 197–211. https://doi.org/10.1130/0016-7606(1981)92<197:TPODRA>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation WOLFGANG SCHLAGER; The paradox of drowned reefs and carbonate platforms. GSA Bulletin 1981;; 92 (4): 197–211. doi: https://doi.org/10.1130/0016-7606(1981)92<197:TPODRA>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Shallow-water carbonate platforms and reefs are drowned when tectonic subsidence or rising sea level outpaces carbonate accumulation, and benthonic carbonate production ceases. Drowned platforms are common in the geologic record, but they present a paradox if one considers rates of processes involved. During the early Holocene, when sea level rose at rates of 6,000 to 10,000 µm/yr (= mm/1,000 yr), most reefs and platforms were outpaced by the rising sea. During the late Holocene with sea level rising 500 to 3,000 µm/yr in the Atlantic-Caribbean area, reefs and platforms started to recover, built to sea level, and prograded seaward, 1,000 µm/yr is thus a conservative estimate of the average growth potential of modern reefs and platforms. Independently, accumulation rates of prograding platforms in the geologic record suggest growth potential in excess of several hundred microns per year.The growth potential of 1,000 µm/yr exceeds any relative rise of sea level caused by long-term processes in the geologic record. Newly formed ocean crust subsides at a maximum of 250 µm/yr, basin subsidence averages 10 to 100 µm/yr, and sea level rises due to increased sea-floor spreading amount to less than 10 µm/yr. Rapid pulses of relative rise of sea level or reduction of benthic growth by deterioration of the environment remain the only plausible explanations of drowning.The geologic record shows examples of both of these processes. Global mass extinctions of reefs and platforms occurred in the middle Cretaceous (eustatic rise due to submarine volcanism or desiccation of a small ocean basin?) and the Late Devonian (global crisis of ocean environment, extraterrestrial cause?). Drowning controlled by regional tectonics prevailed in the Jurassic and Early Cretaceous of the Tethyan realm, and the drowning of Mesozoic platforms in the western North Atlantic seems to have been dictated by plate-tectonic drift to higher latitudes. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Shoreline Definition and Detection: A Review

2005-07-01
Elizabeth H. Boak , Ian L. Turner
Analysis of shoreline variability and shoreline erosion-accretion trends is fundamental to a broad range of investigations undertaken by coastal scientists, coastal engineers, and coastal managers. Though strictly defined as the … Analysis of shoreline variability and shoreline erosion-accretion trends is fundamental to a broad range of investigations undertaken by coastal scientists, coastal engineers, and coastal managers. Though strictly defined as the intersection of water and land surfaces, for practical purposes, the dynamic nature of this boundary and its dependence on the temporal and spatial scale at which it is being considered results in the use of a range of shoreline indicators. These proxies are generally one of two types: either a feature that is visibly discernible in coastal imagery (e.g., high-water line [HWL]) or the intersection of a tidal datum with the coastal profile (e.g., mean high water [MHW]). Recently, a third category of shoreline indicator has begun to be reported in the literature, based on the application of image-processing techniques to extract proxy shoreline features from digital coastal images that are not necessarily visible to the human eye. Potential data sources for shoreline investigation include historical photographs, coastal maps and charts, aerial photography, beach surveys, in situ geographic positioning system shorelines, and a range of digital elevation or image data derived from remote sensing platforms. The identification of a "shoreline" involves two stages: the first requires the selection and definition of a shoreline indicator feature, and the second is the detection of the chosen shoreline feature within the available data source. To date, the most common shoreline detection technique has been subjective visual interpretation. Recent photogrammetry, topographic data collection, and digital image-processing techniques now make it possible for the coastal investigator to use objective shoreline detection methods. The remaining challenge is to improve the quantitative and process-based understanding of these shoreline indicator features and their spatial relationship relative to the physical land–water boundary.
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Coastal systems and low-lying areas

2007-01-01
Robert J. Nicholls , P.P. Wong , V.R. Burket +5 more
Since the IPCC Third Assessment Report (TAR), our understanding of the implications of climate change for coastal systems and low-lying areas (henceforth referred to as ‘coasts’) has increased substantially and … Since the IPCC Third Assessment Report (TAR), our understanding of the implications of climate change for coastal systems and low-lying areas (henceforth referred to as ‘coasts’) has increased substantially and six important policy-relevant messages have emerged. Coasts are experiencing the adverse consequences of hazards related to climate and sea level (very high confidence). Coasts are highly vulnerable to extreme events, such as storms, which impose substantial costs on coastal societies [6.2.1, 6.2.2, 6.5.2]. Annually, about 120 million people are exposed to tropical cyclone hazards, which killed 250,000 people from 1980 to 2000 [6.5.2]. Through the 20th century, global rise of sea level contributed to increased coastal inundation, erosion and ecosystem losses, but with considerable local and regional variation due to other factors [6.2.5, 6.4.1]. Late 20th century effects of rising temperature include loss of sea ice, thawing of permafrost and associated coastal retreat, and more frequent coral bleaching and mortality [6.2.5]. Coasts will be exposed to increasing risks, including coastal erosion, over coming decades due to climate change and sea-level rise (very high confidence). Anticipated climate-related changes include: an accelerated rise in sea level of up to 0.6 m or more by 2100; a further rise in sea surface temperatures by up to 3°C; an intensification of tropical and extratropical cyclones; larger extreme waves and storm surges; altered precipitation/run-off; and ocean acidification [6.3.2]. These phenomena will vary considerably at regional and local scales, but the impacts are virtually certain to be overwhelmingly negative [6.4, 6.5.3].

A third‐generation wave model for coastal regions: 1. Model description and validation

1999-04-15
N. Booij , R.C. Ris , L.H. Holthuijsen
A third‐generation numerical wave model to compute random, short‐crested waves in coastal regions with shallow water and ambient currents (Simulating Waves Nearshore (SWAN)) has been developed, implemented, and validated. The … A third‐generation numerical wave model to compute random, short‐crested waves in coastal regions with shallow water and ambient currents (Simulating Waves Nearshore (SWAN)) has been developed, implemented, and validated. The model is based on a Eulerian formulation of the discrete spectral balance of action density that accounts for refractive propagation over arbitrary bathymetry and current fields. It is driven by boundary conditions and local winds. As in other third‐generation wave models, the processes of wind generation, whitecapping, quadruplet wave‐wave interactions, and bottom dissipation are represented explicitly. In SWAN, triad wave‐wave interactions and depth‐induced wave breaking are added. In contrast to other third‐generation wave models, the numerical propagation scheme is implicit, which implies that the computations are more economic in shallow water. The model results agree well with analytical solutions, laboratory observations, and (generalized) field observations.
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The statistical analysis of a random, moving surface

1957-02-21
M. S. Longuet‐Higgins
The following statistical properties are derived for a random, moving, Gaussian surface: (1) the probability distribution of the surface elevation and of the magnitude and orientation of the gradient; (2) … The following statistical properties are derived for a random, moving, Gaussian surface: (1) the probability distribution of the surface elevation and of the magnitude and orientation of the gradient; (2) the average number of zero-crossings per unit distance along a line in an arbitrary direction; (3) the average length of the contours per unit area, and the distribution of their direction; (4) the average density of maxima and minima per unit area of the surface, and the average density of specular points (i.e, points where the two components of gradient take given values); (5) the probability distribution of the velocities of zero-crossings along a given line; (6) the probability distribution of the velocities of contours and of specular points; (7) the probability distribution of the envelope and phase angle, and hence (8) when the spectrum is narrow, the probability distribution of the heights of maxima and minima and the distribution of the intervals between successive zero-crossings along an arbitrary line. All the results are expressed in terms of the two-dimensional energy spectrum of the surface, and are found to involve the moments of the spectrum up to a finite order only. (1), (3), (4), (5) and (6) are discussed in detail for the special case of a narrow spectrum. The converse problem is also studied and solved: given certain statistical properties of the surface, to find a convergent sequence of approximations to the energy spectrum. The problems arise in connexion with the statistical analysis of the sea surface. (More detailed summaries are given at the beginning of each part of the paper.)

Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model

2008-04-17
John C. Warner , Christopher R. Sherwood , Richard P. Signell +2 more

A fully nonlinear Boussinesq model for surface waves. Part 1. Highly nonlinear unsteady waves

1995-07-10
Ge Wei , James T. Kirby , Stéphan T. Grilli +1 more
Fully nonlinear extensions of Boussinesq equations are derived to simulate surface wave propagation in coastal regions. By using the velocity at a certain depth as a dependent variable (Nwogu 1993), … Fully nonlinear extensions of Boussinesq equations are derived to simulate surface wave propagation in coastal regions. By using the velocity at a certain depth as a dependent variable (Nwogu 1993), the resulting equations have significantly improved linear dispersion properties in intermediate water depths when compared to standard Boussinesq approximations. Since no assumption of small nonlinearity is made, the equations can be applied to simulate strong wave interactions prior to wave breaking. A high-order numerical model based on the equations is developed and applied to the study of two canonical problems: solitary wave shoaling on slopes and undular bore propagation over a horizontal bed. Results of the Boussinesq model with and without strong nonlinearity are compared in detail to those of a boundary element solution of the fully nonlinear potential flow problem developed by Grilli et al. (1989). The fully nonlinear variant of the Boussinesq model is found to predict wave heights, phase speeds and particle kinematics more accurately than the standard approximation.

Coastal Impacts Due to Sea-Level Rise

2008-02-04
Duncan M. FitzGerald , Michael S. Fenster , Britt A. Argow +1 more
The Intergovernmental Panel on Climate Change (2007) recently estimated that global sea level will rise from 0.18 to 0.59 m by the end of this century. Rising sea level not … The Intergovernmental Panel on Climate Change (2007) recently estimated that global sea level will rise from 0.18 to 0.59 m by the end of this century. Rising sea level not only inundates low-lying coastal regions but also contributes to the redistribution of sediment along sandy coasts. Over the long term, sea-level rise (SLR) causes barrier islands to migrate landward while conserving mass through offshore and onshore sediment transport. Under these conditions, coastal systems adjust to SLR dynamically while maintaining a characteristic geometry that is unique to a particular coast. Coastal marshes are susceptible to accelerated SLR because their vertical accretion rates are limited and they may drown. As marshes convert to open water, tidal exchange through inlets increases, which leads to sand sequestration in tidal deltas and erosion of adjacent barrier shorelines.
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The runup of solitary waves

1987-12-01
Costas E. Synolakis
This is a study of the runup of solitary waves on plane beaches. An approximate theory is presented for non-breaking waves and an asymptotic result is derived for the maximum … This is a study of the runup of solitary waves on plane beaches. An approximate theory is presented for non-breaking waves and an asymptotic result is derived for the maximum runup of solitary waves. A series of laboratory experiments is described to support the theory. It is shown that the linear theory predicts the maximum runup satisfactorily, and that the nonlinear theory describes the climb of solitary waves equally well. Different runup regimes are found to exist for the runup of breaking and non-breaking waves. A breaking criterion is derived for determining whether a solitary wave will break as it climbs up a sloping beach, and a different criterion is shown to apply for determining whether a wave will break during rundown. These results are used to explain some of the existing empirical runup relationships.

Modelling storm impacts on beaches, dunes and barrier islands

2009-09-16
Dano Roelvink , Ad Reniers , Ap van Dongeren +3 more

The Digital Shoreline Analysis System (DSAS) Version 4.0 - An ArcGIS extension for calculating shoreline change

2009-01-01
E. Robert Thieler , Emily A. Himmelstoss , Jessica L. Zichichi +1 more
The Digital Shoreline Analysis System (DSAS) version 4.0 is a software extension to ESRI ArcGIS v.9.2 and above that enables a user to calculate shoreline rate-of-change statistics from multiple historic … The Digital Shoreline Analysis System (DSAS) version 4.0 is a software extension to ESRI ArcGIS v.9.2 and above that enables a user to calculate shoreline rate-of-change statistics from multiple historic shoreline positions. A user-friendly interface of simple buttons and menus guides the user through the major steps of shoreline change analysis. Components of the extension and user guide include (1) instruction on the proper way to define a reference baseline for measurements, (2) automated and manual generation of measurement transects and metadata based on user-specified parameters, and (3) output of calculated rates of shoreline change and other statistical information. DSAS computes shoreline rates of change using four different methods: (1) endpoint rate, (2) simple linear regression, (3) weighted linear regression, and (4) least median of squares. The standard error, correlation coefficient, and confidence interval are also computed for the simple and weighted linear-regression methods. The results of all rate calculations are output to a table that can be linked to the transect file by a common attribute field. DSAS is intended to facilitate the shoreline change-calculation process and to provide rate-of-change information and the statistical data necessary to establish the reliability of the calculated results. The software is also suitable for any generic application that calculates positional change over time, such as assessing rates of change of glacier limits in sequential aerial photos, river edge boundaries, land-cover changes, and so on.

Dynamics of marine sands: a manual for practical applications

1997-09-01
R.L. Soulsby

Doubling of coastal flooding frequency within decades due to sea-level rise

2017-04-26
Sean Vitousek , Patrick L. Barnard , Charles H. Fletcher +3 more
Abstract Global climate change drives sea-level rise, increasing the frequency of coastal flooding. In most coastal regions, the amount of sea-level rise occurring over years to decades is significantly smaller … Abstract Global climate change drives sea-level rise, increasing the frequency of coastal flooding. In most coastal regions, the amount of sea-level rise occurring over years to decades is significantly smaller than normal ocean-level fluctuations caused by tides, waves, and storm surge. However, even gradual sea-level rise can rapidly increase the frequency and severity of coastal flooding. So far, global-scale estimates of increased coastal flooding due to sea-level rise have not considered elevated water levels due to waves, and thus underestimate the potential impact. Here we use extreme value theory to combine sea-level projections with wave, tide, and storm surge models to estimate increases in coastal flooding on a continuous global scale. We find that regions with limited water-level variability, i.e., short-tailed flood-level distributions, located mainly in the Tropics, will experience the largest increases in flooding frequency. The 10 to 20 cm of sea-level rise expected no later than 2050 will more than double the frequency of extreme water-level events in the Tropics, impairing the developing economies of equatorial coastal cities and the habitability of low-lying Pacific island nations.
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The State of the World’s Beaches

2018-04-23
Arjen Luijendijk , Gerben Hagenaars , Roshanka Ranasinghe +3 more
Coastal zones constitute one of the most heavily populated and developed land zones in the world. Despite the utility and economic benefits that coasts provide, there is no reliable global-scale … Coastal zones constitute one of the most heavily populated and developed land zones in the world. Despite the utility and economic benefits that coasts provide, there is no reliable global-scale assessment of historical shoreline change trends. Here, via the use of freely available optical satellite images captured since 1984, in conjunction with sophisticated image interrogation and analysis methods, we present a global-scale assessment of the occurrence of sandy beaches and rates of shoreline change therein. Applying pixel-based supervised classification, we found that 31% of the world's ice-free shoreline are sandy. The application of an automated shoreline detection method to the sandy shorelines thus identified resulted in a global dataset of shoreline change rates for the 33 year period 1984-2016. Analysis of the satellite derived shoreline data indicates that 24% of the world's sandy beaches are eroding at rates exceeding 0.5 m/yr, while 28% are accreting and 48% are stable. The majority of the sandy shorelines in marine protected areas are eroding, raising cause for serious concern.
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Sandy coastlines under threat of erosion

2020-03-01
Michalis Vousdoukas , Roshanka Ranasinghe , Lorenzo Mentaschi +4 more
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Beach processes and sedimentation

1998-11-01
1. An Introduction to the Study of Beaches. 2. The Geomorphology of Eroding and Accreting Coasts. 3. Beach Morphology and Sediments. 4. The Changing Level of the Sea. 5. The … 1. An Introduction to the Study of Beaches. 2. The Geomorphology of Eroding and Accreting Coasts. 3. Beach Morphology and Sediments. 4. The Changing Level of the Sea. 5. The Generation of Waves and their Movement Across the Sea. 6. Wave Breaking and Surf-Zone Processes. 7. Beach Profiles and Cross-Shore Sediment Transport. 8. Wave-Generated Currents in the Nearshore. 9. The Longshore Transport of Sediments on Beaches. 10. Shoreline Planforms and Models to Simulate Their Evolution. 11. Nearshore Morphodynamics. 12. The Protection of Our Coasts. Index.

Experimental investigation on hydrodynamic performance of a helmholtz resonator-based floating breakwater array

2025-06-25
Yuhang Zhang , Jin Xu , P. Kar +1 more | Ocean Engineering

Identifying coastline positions and types based on both the moisture content and feature knowledge of ground objects

2025-06-24
Chao Chen , Shaojun Gong , Nan Xu +4 more | International Journal of Digital Earth

Design optimization of inclined pile permeable breakwater based on a CFD-SVR-WO framework

2025-06-23
Zunfeng Du , Yuan Yang , Haiming Zhu +3 more | Ocean Engineering

Grain size distribution characteristics of sediments in recreational beaches: a case study of three major beaches in Zhanjiang City of western Guangdong

2025-06-23
Jiehua Chen , Chloe Tan , Min Yuan +4 more | Anthropocene Coasts
Abstract Recreational beaches are widely distributed in coastal cities. Investigating the coupling mechanisms between anthropogenic interventions and natural coastal processes on sediment grain-size distribution is critical for maintaining and enhancing … Abstract Recreational beaches are widely distributed in coastal cities. Investigating the coupling mechanisms between anthropogenic interventions and natural coastal processes on sediment grain-size distribution is critical for maintaining and enhancing recreational beach functionality and value. This study examines three major recreational beaches within Zhanjiang Bay, conducting comparative analyses of surface sediment characteristics including representative grain-size metrics, granulometric composition, and statistical parameters. Key findings include: (a) significant variations in mode size (0.87–1.89 φ) and D 10 values (-0.80 to -0.09 φ) among the three beaches, contrasted with limited differences in D 50 and D 90 metrics; (2) dominance of medium sand (26.16–39.14%) and coarse sand (26.75–31.43%) fractions, supplemented by fine and very coarse sand components, with central transects exhibiting higher medium-coarse sand concentrations than southern/northern sections; (3) sorting coefficient gradients (0.90–1.21) ranking central &gt; northern &gt; southern beaches, while mean grain size (0.83–1.21 φ), skewness (-0.12 to -0.02), and kurtosis (0.87–1.18) show no distinct spatial patterns. Sediment grain-size distribution patterns are governed by four primary mechanisms: artificial nourishment inputs, anthropogenic sediment modification (harvesting/excavation), natural sediment supply processes, and hydrodynamic forcing. This research establishes a typical framework for characterizing recreational beach sediments, advancing understanding of multi-factor controlled grain-size distribution patterns and sediment transport dynamics.

Seasonal rotation of California pocket beaches

2025-06-22
Jonathan A. Warrick , Daniel Buscombe , Kilian Vos +2 more | Earth Surface Processes and Landforms
Abstract Pocket beaches are short, headland‐bound coastal landforms that may exhibit shoreline rotation in response to time‐varying wave conditions. Here we examine the presence, location and style of pocket beach … Abstract Pocket beaches are short, headland‐bound coastal landforms that may exhibit shoreline rotation in response to time‐varying wave conditions. Here we examine the presence, location and style of pocket beach rotation along the 1700 km coast of California using a comprehensive 22‐year satellite‐derived shoreline dataset. These analyses identify 23 pocket beaches that exhibit annual cycles of rotation, and these beaches have two general types. In southern California, pocket beaches rotate clockwise, or towards the south, in the winter season (‘winter southward’ transport of sand). These beaches have symmetric rotation patterns and strong seasonality in wave direction (winter west swell and summer south swell), which is indicative of rotation from seasonal oscillations in longshore sediment transport. In northern California, pocket beaches rotate counterclockwise, or towards the north, in the winter (‘winter northward’ transport of sand), and they are characterized by strong asymmetry (winter beach is overall narrower than the summer beach) and strong seasonality in wave power. Rotation of these northern California beaches is related to both cross‐shore and longshore sediment transport, caused by large west‐to‐northwest swell of the winter and smaller northwest wind waves of the summer. We acknowledge that many more rotating pocket beaches likely exist in California owing to the undersampling of the smallest beaches in the source data. In the end, we conclude that seasonally rotating pocket beaches are a fundamental coastal landform type of the California coast, owing to its wave seasonality and rocky and cliff‐backed morphology.

Ship-generated wave-induced sediment dynamics in upper St. Lawrence River: analysis of field data

2025-06-21
A A Kamgar Haghighi , Colin Rennie , Ioan Nistor | Natural Hazards
Abstract This study examines the effects of combined ship-generated waves and wind-driven waves on sediment dynamics in the upper St. Lawrence River, focusing on two sites at Mariatown and Jacobs … Abstract This study examines the effects of combined ship-generated waves and wind-driven waves on sediment dynamics in the upper St. Lawrence River, focusing on two sites at Mariatown and Jacobs Island in Ontario, Canada. Six loggers installed at the two study sites recorded wave and turbidity data over a period of 300 days to distinguish the influences of natural versus ship-induced waves on sediment resuspension. The findings indicate that wind-driven waves regularly resuspend sediment, establishing a baseline turbidity level, while ship-generated waves cause short-lived but intense turbidity spikes, particularly in shallow zones with fine sediment. Spectral signal analyses, including synthetic natural wave modeling and frequency-based filtering, are used to isolate the frequency characteristics of primary and secondary ship-generated waves from those of natural wind waves, enabling a focused assessment of each wave type’s impact on sediment dynamics. Wavelet analysis is applied as a validation tool to confirm the spectral localization of separated wave components. The study demonstrates that factors such as water depth, sediment type, and proximity to the navigation channel strongly influence local turbidity responses. While historical shoreline imagery is used to provide spatial context, shoreline change was not formally analyzed in this study. Overall, the results offer a replicable framework for isolating wave contributions to sediment resuspension and support future efforts in sustainable sediment and shoreline management in modified river environments.

Laboratory investigation of the hydrodynamic performance of a pile-supported breakwater with a permeable curved superstructure and rock-fill layer

2025-06-20
Ziwang Li , Zhenlu Wang , Bingchen Liang +1 more | Ocean Engineering

Diffusion-limited settling of highly porous particles in density-stratified fluids

2025-06-20
Robert Hunt , Roberto Camassa , Richard M. McLaughlin +1 more | Proceedings of the National Academy of Sciences
The vertical transport of solid material in a stratified medium is fundamental to a number of environmental applications, with implications for the carbon cycle and nutrient transport in marine ecosystems. … The vertical transport of solid material in a stratified medium is fundamental to a number of environmental applications, with implications for the carbon cycle and nutrient transport in marine ecosystems. In this work, we study the diffusion-limited settling of highly porous particles in a density-stratified fluid through a combination of experiment, analysis, and numerical simulation. By delineating and appealing to the diffusion-limited regime wherein buoyancy effects due to mass adaptation dominate hydrodynamic drag, we derive a simple expression for the steady settling velocity of a sphere as a function of the density, size, and diffusivity of the solid, as well as the density gradient of the background fluid. In this regime, smaller particles settle faster, in contrast with most conventional hydrodynamic drag mechanisms. Furthermore, we outline a general mathematical framework for computing the steady settling speed of a body of arbitrary shape in this regime and compute exact results for the case of general ellipsoids. Using hydrogels as a highly porous model system, we validate the predictions with laboratory experiments in linear stratification for a wide range of parameters. Last, we show how the predictions can be applied to arbitrary slowly varying background density profiles and demonstrate how a measured particle position over time can be used to reconstruct the background density profile.
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An experimental study of using artificial reefs as scour protection around an offshore wind monopile

2025-06-20
Xin Liu , Jianjun Chen , Lei Yu +4 more | Ocean Engineering

Tracer dispersion by surfzone eddies: assessing the impact of undertow vertical shear

2025-06-19
Simon Treillou , Patrick Marchesiello , Christine M. Baker +2 more | Journal of Physical Oceanography
Abstract The nearshore region, which includes both the surf zone and the inner shelf, is a highly dynamic environment where eddies and rip currents of different scales coexist and interact. … Abstract The nearshore region, which includes both the surf zone and the inner shelf, is a highly dynamic environment where eddies and rip currents of different scales coexist and interact. Understanding transport and mixing in this interface between land and sea is essential for many reasons, not least to better predict the fate of pollutants, fish larvae and sediments. Previous modeling studies on the transport of passive tracers have primarily used depth-averaged Boussinesq models. Although these models have provided valuable information, they seem to generally underestimate mixing in the surf zone, while they overestimate it on the inner shelf. CROCO, a 3D free-surface, wave-resolving model, is used here to study the effect of vertical dimension on surfzone eddies and nearshore tracer dispersion. The model is applied to both a directional wave basin experiment and a large-scale dye release experiment conducted in 2009 at Imperial Beach, California. By comparing simulations with and without vertical shear in surfzone currents, we isolate various mixing processes, such as shear dispersion, flash rips and mini-rips, recently identified as resulting from undertow vertical shear instability. Quantifying each dispersion process in terms of bulk diffusivity reveals the important role of vertical shear in weakening flash rips (through a reduction of inverse kinetic energy cascade) and hence tracer dispersion offshore, while increasing mixing in the surf zone due to mini-rips. This study suggests potential improvements for the parameterization of coarser or simpler models to obtain a more accurate representation of nearshore transport and dispersion mechanisms.

One-Dimensional Plume Dispersion Modeling in Marine Conditions (SEDPLUME1D-Model)

2025-06-18
Leo C. van Rijn | Journal of Marine Science and Engineering
Dredging of fine sediments and dumping of fines at disposal sites produce passive plumes behind the dredging equipment. Each type of dredging method has its own plume characteristics. All types … Dredging of fine sediments and dumping of fines at disposal sites produce passive plumes behind the dredging equipment. Each type of dredging method has its own plume characteristics. All types of dredging operations create some form of turbidity (spillage of dredged materials) in the water column, depending on (i) the applied method (mechanical grab/backhoe, hydraulic suction dredging with/without overflow), (ii) the nature of the sediment bed, and (iii) the hydrodynamic conditions. A simple parameter to represent the spillage of dredged materials is the spill percentage (Rspill) of the initial load. In the case of cutter dredging and hopper dredging without overflow, sediment spillage is mostly low, with values in the range of 1% to 3%, The spill percentage is higher, in the range of 3% to 30%, for hopper dredging of mud with intensive overflow. Spilling of dredged materials also occurs at disposal sites. The spill percentage is generally low, with values in the range of 1% to 3%, if the load is dumped through bottom doors in deep water, creating a dynamic plume which descends rapidly to the bottom with cloud velocities of 1 m/s. The most accurate approach to study passive plume behavior is the application of a 3D model, which, however, is a major, time-consuming effort. A practical 1D plume dispersion model can help to identify the best parameter settings involved and to conduct fast scan studies. The proposed 1D model represents equations for dynamic plume behavior, as well as passive plume behavior including advection, diffusion and settling processes.

Numerical Simulation of Ship Wave Characteristics Under Different Navigation Conditions in the Restricted Waterway of the Pinglu Canal

2025-06-18
Chu Zhang , T.C.E. Cheng , Shishuang Wu +6 more | Water
The Pinglu Canal is a strategic inland restricted waterway under construction in southwest China. Its ship wave superposition characteristics under conditions of high-density shipping and large ships may threaten navigation … The Pinglu Canal is a strategic inland restricted waterway under construction in southwest China. Its ship wave superposition characteristics under conditions of high-density shipping and large ships may threaten navigation safety, but little related research has been performed. Based on the Pinglu Canal project, this study uses the XBeach numerical model, which is validated by field observations on the Chengzi River waterway, to analyze the ship wave characteristics under single-ship navigation (SN) and two-ship navigation in opposite directions (2NOD). The results show the influences of ship type and water depth. For SN, secondary waves of the navigation administration boat (NAB) dominate, with wave height decreasing as water depth increases. Larger cargo ships (CSs) present significant primary wave effects and a complex relationship between the secondary wave’s height and water depth. For 2NOD, the NAB wave effect is stronger due to superposition. As for larger CSs, the primary wave effect is significantly enhanced and occupies the dominant position, with secondary wave height tending to increase with the increase in water depth. The study reveals the characteristics of single-ship and two-ship waves in the Pinglu Canal, providing a theoretical basis and technical support for ship wave risk assessment and ecological revetment design.

Experimental investigation on wave attenuation capacity of kelp farms

2025-06-17
Yushun Lian , Jiantao Ma , D.J. Li +5 more | Ocean Engineering

Machine Learning Beach Attendance Forecast Modelling from Automatic Video-Derived Counting

2025-06-17
Bruno Castelle , David Carayon , Jeoffrey Dehez +6 more | Journal of Marine Science and Engineering
Accurate predictions of beach user numbers are important for coastal management, resource allocation, and minimising safety risks, especially when considering surf-zone hazards. The present work applies an XGBoost model to … Accurate predictions of beach user numbers are important for coastal management, resource allocation, and minimising safety risks, especially when considering surf-zone hazards. The present work applies an XGBoost model to predict beach attendance from automatically video-derived data, incorporating input variables such as weather, waves, tide, and time (e.g., day hour, weekday). This approach is applied to data collected from Biscarrosse Beach during the summer of 2023, where beach attendance varied significantly (from 0 to 2031 individuals). Results indicate that the optimal XGBoost model achieved high predictive accuracy, with a coefficient of determination (R2) of 0.97 and an RMSE of 70.4 users, using daily mean weather data, tide and time as input variables, i.e., disregarding wave data. The model skilfully captures both day-to-day and hourly variability in attendance, with time of day (hour) and daily mean air temperature being the most influential variables. An XGBoost model using only daily mean temperature and hour of the day even shows good predictive accuracy (R2 = 0.90). The study emphasises the importance of daily mean weather data over instantaneous measurements, as beach users tend to plan visits based on forecasts. This model offers reliable, computationally inexpensive, and high-frequency (e.g., every 10 min) beach user predictions which, combined with existing surf-zone hazard forecast models, can be used to anticipate life risk at the beach.

A simple model to simulate beach state variability

2025-06-17
Blessing Nwanosike , Dominic E. Reeve , Harshinie Karunarathna | Coastal Engineering Journal

Numerical Modelling of Wave Height using Wind-Tide Interactions in Coastal Flooding

2025-06-15
Irwan Ibrahim , Mardiha Mokhtar , Mohd Effendi Daud +4 more | Journal of Advanced Research in Fluid Mechanics and Thermal Sciences
Pantai Punggur, Batu Pahat is a bustling town located on the Southwest Coast of Peninsular Malaysia, situated along the west coast of Malaysia. Despite its bustling nature, the area is … Pantai Punggur, Batu Pahat is a bustling town located on the Southwest Coast of Peninsular Malaysia, situated along the west coast of Malaysia. Despite its bustling nature, the area is prone to coastal flooding. In response, coastal defence structures have been constructed to protect the coastline. However, the issue lies that this structure cannot fully prevent coastline exposure to wave overtopping caused by strong waves or coastal inundation from high tidal fluctuations that exceed normal sea levels. Pantai Punggur has undergone the concerning issue, and it is worsening. Therefore, this study uses numerical modelling (MIKE21 Software) to investigate the wave scenario from the historical data of wind and tide in Pantai Punggur, Batu Pahat. The study location was digitised, and a new model MESH was developed in the MIKE21 Zero MESH Generator. The historical data from the ERA5-Reanalysis Dataset covering all 12 months (2022) at one-hour intervals was collected. To validate the new model MESH, the RMSE method was employed, which required achieving a result below the 10% threshold. Correlation analysis was conducted monthly throughout the year and revealed distinct relationships between significant wave height (SWH) and wind speed (indicating wave overtopping) and tidal levels (indicating coastal inundation). The correlation between tidal levels and SWH showed a stronger correlation than with wind speed, with the highest R-value reaching 0.5886 (34.64%). Hence, it can be seen that the stronger correlation between tidal level and SWH compared to wind speed and SWH, suggests that tidal fluctuations have a more substantial impact on wave heights and the potential fall on coastal inundation rather than wave overtopping resulting in coastal flooding. The current studies provide essential information relevant to conservation practices and future planning.

Multidecadal evolution of the shoreline change at Agadir beach (Morocco): A GIS and high-resolution satellite imagery analysis

2025-06-14
M'hamed Nmiss , Mhamed Amyay , Nadia Atiki +3 more | Pesquisas em Geociências
Beaches are extremely fragile and dynamic natural environments, where waves, coastal currents, and winds perpetually deposit and move sediments. The evolution of these beaches can only be envisaged by monitoring … Beaches are extremely fragile and dynamic natural environments, where waves, coastal currents, and winds perpetually deposit and move sediments. The evolution of these beaches can only be envisaged by monitoring coastline dynamics at different spatiotemporal scales. In recent years, the use of high-resolution satellite images and GIS has become an indispensable tool for assessing beach evolutionary trends. In this contribution, we emphasize the importance of these new technologies for monitoring shoreline evolution on highly anthropized beaches, focusing on the case of Agadir beach on Morocco's Atlantic coast. A diachronic analysis of shoreline evolution was carried out over a period of 55 years extending from 1968 to 2023. This analysis is based on both high-resolution satellite images from various sensors (Corona, OrbView-3, Pleiades, WorldView-2) and the DSAS (Digital Shoreline Analysis System) tool integrated into ArcGIS©. The results obtained show a contrasting evolution, with a general trend towards erosion in the center and south of the beach, and an accentuated beach nourishment to the north. This trend is mainly attributed to the construction of a port complex (commercial harbour, fishing port, and marina) and to the various coastal developments undertaken on the beach.

Numerical study on dissipation rates of wave and roller energies under spilling breakers: Closures for dissipation rates

2025-06-13
C. M. Wang , Yi-Hsuan Kuan , Cheng-Hsien Lee +1 more | Ocean Engineering

Numerical simulation of wave attenuation and shoreline response in a coastal region with submerged breakwater

2025-06-13
Min Roh , Chang-Heon Gwon , Sooncheol Hwang +3 more | Frontiers in Marine Science
The non-hydrostatic numerical model NHWAVE was employed to investigate the hydrodynamic behavior of a coastal region with submerged breakwater, focusing on the structural dimensions and incident wave conditions. In the … The non-hydrostatic numerical model NHWAVE was employed to investigate the hydrodynamic behavior of a coastal region with submerged breakwater, focusing on the structural dimensions and incident wave conditions. In the numerical experiment, regular waves of varying specifications were used as incident waves, and the breakwater dimensions were adjusted based on the offshore distance from the shoreline and its vertical distance from the water surface to the crest. The above experimental conditions calculated water surface displacement and velocity at different depths. The shoreline response, including erosion and accretion, was predicted by assessing nearshore flow patterns, while the wave attenuation effect was quantified based on wave height variations. The results indicate that wave attenuation is significantly influenced by breaking-induced currents generated during wave interaction with the breakwater crest. A shorter vertical distance from submerged breakwater crest resulted in stronger breaking-induced currents. The rotational direction of vortex-induced nearshore flow patterns significantly influences shoreline response, resulting in either erosion or accretion. These findings provide insights into the hydrodynamic and sediment transport mechanisms associated with submerged breakwaters, contributing to optimizing coastal protection measures.

Quantifying future local impacts of sea level rise on buildings and infrastructure

2025-06-13
Dylan Sanderson , Therese P. McAllister | International Journal of Disaster Risk Reduction

Satellite-derived bathymetry in Case II coastal waters during tidal ebb and flow without in-situ data: a case study around Jiaozhou Bay, Yellow Sea

2025-06-12
Fanlin Yang , Shaoyu Li , Chao Qi +3 more | International Journal of Remote Sensing

Rogue wave patterns and hybrid solutions of rogue wave and breather for the Yajima-Oikawa-Newell system

2025-06-09
Suriguga Bai , Hasi Gegen | Physica Scripta
Abstract For the Yajima-Oikawa-Newell (YON) system, we show that the rogue waves in the short-wave component exhibit three states: dark state, intermediate state and bright state, whereas the rogue waves … Abstract For the Yajima-Oikawa-Newell (YON) system, we show that the rogue waves in the short-wave component exhibit three states: dark state, intermediate state and bright state, whereas the rogue waves in the long-wave component show only a dark state, or only a bright state, or both dark state and bright state depending on values of $\alpha, \delta$. We establish a connection between the $N$-th order rogue wave patterns for the YON system and the root structures of the Adler-Moser polynomials. We demonstrate that the rogue wave patterns result from a combination of operations including rotation, stretch, shear and a constant phase shift to the root structures of the Adler-Moser polynomials. We present the predicted fourth and fifth-order rogue wave patterns in the short-wave component for the dark state, intermediate state and bright state, which achieve excellent agreement with the corresponding true rogue wave patterns. Moreover, through a generalized long-wave limit method, we derive the hybrid solutions of rogue wave and breather for the YON system from its breather solutions. Each hybrid solution contains all free parameters from the individual rogue wave and breather involved in this hybrid solution. By managing the phase parameters of the breathers, we illustrate diverse interaction phenomena between breathers and rogue waves.

Extreme wave transformation and runup on a beach fronted by a very steep forereef profile

2025-06-06
Julian Rodríguez-Burguette , Alec Torres‐Freyermuth , Gemma L. Franklin +1 more | Applied Ocean Research

Progress in large-scale wave flume experimental research in China (2014–2024)

2025-06-02
Songgui Chen , Hanbao Chen , Zongshuan Duan +4 more | Ocean Engineering

Are Equilibrium Shoreline Models Just Convolutions?

2025-06-01
Sean Vitousek , Daniel Buscombe , Eduardo Gomez‐de la Peña +5 more | Journal of Geophysical Research Earth Surface
Abstract Yes. Equilibrium shoreline models, which simulate wave‐driven cross‐shore erosion and accretion, are mathematically equivalent to a discrete convolution (i.e., a weighted, moving average) of a time series of wave‐forcing … Abstract Yes. Equilibrium shoreline models, which simulate wave‐driven cross‐shore erosion and accretion, are mathematically equivalent to a discrete convolution (i.e., a weighted, moving average) of a time series of wave‐forcing conditions with a parameterized memory‐decay kernel function. The direct equivalence between equilibrium shoreline models and convolutions reveals key theoretical aspects of equilibrium behavior. Convolutions (representing quasi‐low‐pass filter operations) provide an intuitive theoretical description of shoreline erosion and accretion behavior in response to waves: that is, shoreline position often mirrors the weighted moving average of wave time series. Model‐convolution equivalence also provides a conceptual basis to interpret, evaluate, and construct data‐driven Machine‐Learning/Deep‐Learning (ML/DL) models that use convolutions to extract features from data and then apply them for prediction (e.g., Convolutional Neural Networks (CNNs)). Finally, our findings provide a methodological pathway (based on Fourier transforms) for future understanding of wave‐driven shoreline change, which can be used to interpret the coherence between the frequency spectrum of the processes of waves and shoreline change and construct more computationally efficient and effective shoreline‐modeling approaches.

Sediment transport on sandy slopes under solitary waves

2025-06-01
S. Samuel Li , Huabin Shi | Physics of Fluids
The sheet-flow sediment transport on sandy slopes under tsunami-like solitary waves is investigated in detail by using a two-phase-resolved Smoothed Particle Hydrodynamics model. The model is well calibrated and verified … The sheet-flow sediment transport on sandy slopes under tsunami-like solitary waves is investigated in detail by using a two-phase-resolved Smoothed Particle Hydrodynamics model. The model is well calibrated and verified by simulating the run-up and breaking of solitary waves on both immovable and movable slopes as well as the resulted erosion and deposition on sandy beaches. The profiles of water pressure, two-phase velocities and shear stresses, and sediment fluxes on the sandy slope before and after the breaking of solitary waves are examined. The temporal evolution of bed shear stress, thickness of sheet-flow layer, and sediment transport rate at locations before and after wave breaking is compared. During the run-up of solitary waves, the change of pore water pressure in the sandy slope follows closely with waves resulting in a “high-pressure wave front.” Sediment moves mainly in the thin sheet-flow layer, in which the shear stress of sediment phase is much higher than the fluid stress due to the intense interparticle collision and friction. The profile of bed-parallel sediment flux in the sheet-flow layer presents parabolic with the peak at the layer center. Relationships between the sheet-flow sediment transport rate and Shields number at locations below and above the initial water level are compared. Further numerical experiments show that the solitary wave height has a minor effect on the relationships between sediment transport rate and Shields number below the initial water near the wave-breaking point while enhances the relations in the swash zone above the initial sea surface.

Machine Learning-Based Shoreline Analysis and Prediction for the Puerto Escondido Coastal Region: Assessing Erosion Patterns and Future Changes Using Remote Sensing and GIS Techniques

2025-06-01
V Balajishanmugam , Sulaiman Alamro , Radwa Marzouk +1 more | Journal of South American Earth Sciences

Structure-preserving approximations of the Serre-Green-Naghdi equations in standard and hyperbolic form

2024-08-05
Hendrik Ranocha , Mario Ricchiuto
We develop structure-preserving numerical methods for the Serre-Green-Naghdi equations, a model for weakly dispersive free-surface waves. We consider both the classical form, requiring the inversion of a non-linear elliptic operator, … We develop structure-preserving numerical methods for the Serre-Green-Naghdi equations, a model for weakly dispersive free-surface waves. We consider both the classical form, requiring the inversion of a non-linear elliptic operator, and a hyperbolic approximation of the equations, allowing fully explicit time stepping. Systems for both flat and variable topography are studied. Our novel numerical methods conserve both the total water mass and the total energy. In addition, the methods for the original Serre-Green-Naghdi equations conserve the total momentum for flat bathymetry. For variable topography, all the methods proposed are well-balanced for the lake-at-rest state. We provide a theoretical setting allowing us to construct schemes of any kind (finite difference, finite element, discontinuous Galerkin, spectral, etc.) as long as summation-by-parts operators are available in the chosen setting. Energy-stable variants are proposed by adding a consistent high-order artificial viscosity term. The proposed methods are validated through a large set of benchmarks to verify all the theoretical properties. Whenever possible, comparisons with exact, reference numerical, or experimental data are carried out. The impressive advantage of structure preservation, and in particular energy preservation, to resolve accurately dispersive wave propagation on very coarse meshes is demonstrated by several of the tests.
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