scholarly journals PROBLEMS OF SEDIMENTS TRANSPORT MODELING IN THE COASTAL AREA

2021 ◽  
Vol 49 (1) ◽  
pp. 93-141
Author(s):  
R. D. Kosyan ◽  
B. V. Divinsky
Keyword(s):  
Sediment Transport ◽  
Surface Waves ◽  
Wave Field ◽  
Frequency Distribution ◽  
Coastal Zone ◽  
Bottom Sediments ◽  
Wave Energy ◽  
Laboratory Experiments ◽  
Wind Waves ◽  
Wave Spectrum

Due to the development of measuring instruments, a more detailed analysis of the wave field and the field of suspended sediments spatio-temporal characteristics has become possible. Through the efforts of Russian specialists over the past decades: A unique database of observations of the sediment movement in storm situations in different physical and geographical areas of the coastal zone of the Black, Baltic, North, Mediterranean, South China Seas has been collected, supplemented by extensive data of laboratory experiments in the best laboratory in Europe (Hannover, Germany). New experimental material has been obtained to determine the physical features of sediment transport by wave flow. The main mechanisms controlling the amplitude and phase relationships of the concentration fluctuations and discharge of suspended sediment on time scales less than the period of the peak of the wind wave spectrum are considered. The presence of low-frequency fluctuations in sediment concentration with a period of the order of several periods of wind waves and an amplitude several times higher than the average value of concentration is noted. The previously unexplored problem of the wave energy frequency distribution in the spectrum of surface waves influence on the sediment transport has been analyzed. Differences in the response of the washed-out bottom to an external disturbance, represented by irregular surface waves with constant integral characteristics (significant wave height and period of the spectrum peak) and variable wave energy frequency distribution, were revealed. The influence of swell waves on the redistribution of bottom sediments in the sea coastal zone was investigated. It is shown that dividing the wave field into separate components allows a more correct description of the spatiotemporal structure of surface waves, as well as a significant refinement of the bottom sediment transport schemes in the coastal zone. Using the example of the Anapa bay bar, it is shown that situations are possible in which the alongshore flow of bottom sediments is almost completely determined by swell waves. The results of field and laboratory experiments make it possible to determine the directions for further research on the creation of physically based models of sediment transport by waves and wave currents.

DYNAMICS OF THE NEARSHORE ZONE OF KALAMITSKIY GULF (BLACK SEA) UNDER INFLUENCE OF WIND WAVES

2017 ◽  
Author(s):  
Vladimir Fomin ◽  
Vladimir Fomin ◽  
Konstantin Gurov ◽  
Konstantin Gurov ◽  
Vladimir Udovik ◽  
...  
Keyword(s):  
Coastal Zone ◽  
Bottom Sediments ◽  
Wind Waves ◽  
Bottom Topography ◽  
Fast Response ◽  
Nearshore Zone ◽  
Qualitative And Quantitative ◽  
Waves And Currents ◽  
Quantitative Assessments ◽  
Sedimentation Processes

Coastal zone dynamics is especially interesting for interdisciplinary researchers. This is due to general retreat of the coast of the Western Crimea and the fast response in the beach ar-ea. This justifies the need for monitoring of morphodynamic processes in the coastal zone of Crimea with the aim of qualitative and quantitative assessments of modern coastal trans-formation, as well as forecasts of possible changes. XBeach model has been used to simulate dynamics of waves and currents, sediment transport and changes in bottom topography, as well as the processes of drying and flooding of coastal areas. Erosion and sedimentation processes for the bottom sediments of the coastal zone of the Western Crimea have been numerically studied. The bottom profile has been reconstructed on the basis of bathymetric investigations in the coastal zone of the Western Crimea. Numerical simulations have been performed for various parameters of the bed composition and wind waves. Two fractions of bottom sediments have been considered for numerical experiments. The obtained results show that XBeach model can be successfully applied to simulate the bed profile evolution and changes in bottom sediment fractionation.

DYNAMICS OF THE NEARSHORE ZONE OF KALAMITSKIY GULF (BLACK SEA) UNDER INFLUENCE OF WIND WAVES

2017 ◽  
Author(s):  
Vladimir Fomin ◽  
Vladimir Fomin ◽  
Konstantin Gurov ◽  
Konstantin Gurov ◽  
Vladimir Udovik ◽  
...  
Keyword(s):  
Coastal Zone ◽  
Bottom Sediments ◽  
Wind Waves ◽  
Bottom Topography ◽  
Fast Response ◽  
Nearshore Zone ◽  
Qualitative And Quantitative ◽  
Waves And Currents ◽  
Quantitative Assessments ◽  
Sedimentation Processes

Coastal zone dynamics is especially interesting for interdisciplinary researchers. This is due to general retreat of the coast of the Western Crimea and the fast response in the beach ar-ea. This justifies the need for monitoring of morphodynamic processes in the coastal zone of Crimea with the aim of qualitative and quantitative assessments of modern coastal trans-formation, as well as forecasts of possible changes. XBeach model has been used to simulate dynamics of waves and currents, sediment transport and changes in bottom topography, as well as the processes of drying and flooding of coastal areas. Erosion and sedimentation processes for the bottom sediments of the coastal zone of the Western Crimea have been numerically studied. The bottom profile has been reconstructed on the basis of bathymetric investigations in the coastal zone of the Western Crimea. Numerical simulations have been performed for various parameters of the bed composition and wind waves. Two fractions of bottom sediments have been considered for numerical experiments. The obtained results show that XBeach model can be successfully applied to simulate the bed profile evolution and changes in bottom sediment fractionation.

VARIABILITY OF THE SUSPENDED SEDIMENT DYNAMICS UNDER IRREGULAR WAVES

2017 ◽  
Author(s):  
Рубен Косян ◽  
Ruben Kosyan ◽  
Boris Divinsky ◽  
Boris Divinsky
Keyword(s):  
Bottom Sediment ◽  
Suspended Sediment ◽  
Frequency Distribution ◽  
Bottom Sediments ◽  
Wave Energy ◽  
Suspended Solids ◽  
Irregular Waves ◽  
Spectral Peak ◽  
Sediment Suspension ◽  
The Impact

The main objective of this paper is an analysis of the impact of the frequency distribution of wave energy on the dynamics of bottom sediment suspension as well as a study of the features of bottom sediments suspension during the passage of waves groups of varying shape and intensity. It is shown that the concentration of wave energy in the primary spectral peak promotes redistribution vertically suspended solids. Laws of suspension within the group are largely determined by the parameters of bottom roughness and the presence (absence) of ripples.

Coupling of surface and internal gravity waves: a mode coupling model

1976 ◽  
Vol 77 (1) ◽  
pp. 185-208 ◽  
Author(s):  
Kenneth M. Watson ◽  
Bruce J. West ◽  
Bruce I. Cohen
Keyword(s):  
Energy Transfer ◽  
Surface Wave ◽  
Internal Wave ◽  
Surface Waves ◽  
Wave Field ◽  
Internal Waves ◽  
Wave Spectrum ◽  
Coupled Model ◽  
Internal Gravity Waves ◽  
Growth Time

A surface-wave/internal-wave mode coupled model is constructed to describe the energy transfer from a linear surface wave field on the ocean to a linear internal wave field. Expressed in terms of action-angle variables the dynamic equations have a particularly useful form and are solved both numerically and in some analytic approximations. The growth time for internal waves generated by the resonant interaction of surface waves is calculated for an equilibrium spectrum of surface waves and for both the Garrett-Munk and two-layer models of the undersea environment. We find energy transfer rates as a function of undersea parameters which are much faster than those based on the constant Brunt-ViiisSila model used by Kenyon (1968) and which are consistent with the experiments of Joyce (1974). The modulation of the surface-wave spectrum by internal waves is also calculated, yielding a ‘mottled’ appearance of the ocean surface similar to that observed in photographs taken from an ERTS1 satellite (Ape1 et al. 1975b).

REFRACTIONOF WIND WAVES IN MESHWATER ZONNE BY THE SHORES OF ANY UNDERWATER SLOPE MORFOSTRUCTURE

2018 ◽  
Author(s):  
А. Марченко ◽  
A. Marchenko ◽  
И. Никитин ◽  
I. Nikitin
Keyword(s):  
Wave Field ◽  
Coastal Zone ◽  
Coastal Water ◽  
Wind Waves ◽  
Numerical Results ◽  
Theoretical Studies ◽  
Wave Tank ◽  
Analytical Technique ◽  
Underwater Slope ◽  
The Given

The graphical analytical technique for refraction waves in coastal water areas under condition of water slope relief in shapes of bathymetry charts. The given technique is based on results of theoretical studies in water areas refractions in sea bays made by the authoress. The convergences data obtained are suited for foolproof calculations results for proposed methods of wave tank supervision along with natural of measurements and numerical results. The given technique make it possible to recreate the approximate picture wave field refraction on the coastal zone up to the border of waves turnover.

Experimental Investigations of Combined Flow Sediment Transport

2019 ◽  
Vol 89 (8) ◽  
pp. 808-814 ◽  
Author(s):  
Everett Smith ◽  
Max S. Daniller-Varghese ◽  
Paul M. Myrow ◽  
David Mohrig
Keyword(s):  
Surface Wave ◽  
Sediment Transport ◽  
Surface Waves ◽  
Wave Field ◽  
Turbidity Currents ◽  
Marine Environments ◽  
Shallow Marine ◽  
Combined Flow ◽  
Hyperpycnal Flows ◽  
Gravity Driven

Abstract In shallow marine environments gravity-driven currents (e.g., hyperpycnal flows) often traverse surface wave fields, and the resulting complex flows are key mechanisms for offshore sediment transport. Our laboratory experiments illustrate how surface waves alter sediment transport in gravity-driven density currents. The addition of a wave field to a gravity-driven current resulted in a 7–8.5% increase in the downslope transport of the deposit volume. Additionally, oscillatory velocities recorded at downslope locations in surface-wave-altered turbidity currents were larger than wave-field velocities measured at the same location without a turbidity current. These observations indicate that surface waves alter turbidity currents in a longitudinally complex manner whereby the influence of oscillatory currents is transported downslope within the body of the turbidity current. These effects were observed in a conservative case: the maximum orbital velocities of the wave field were an order of magnitude less than the maximum unidirectional velocities of the current. We predict that if the velocities of the wave field and the current were sub-equal, a plausible scenario for hyperpycnal flows in near-shore, deltaic, and proximal shelf environments, these effects would be substantially more effective. This work has significant implications for modeling offshore sediment transport in shallow marine environments and for interpreting the deposits of such flows, most notably that the presence or absence of combined-flow ripples might not indicate whether the current was deposited above or beneath wave base.

scholarly journals Influence of Storm Conditions on Changes in the Granulometric Composition of Bottom Sediments in the Coastal Zone of the Western Crimea

2021 ◽  
Author(s):  
K. I. Gurov ◽  
V. V. Fomin ◽  
◽  
Keyword(s):  
Coastal Zone ◽  
Bottom Sediments ◽  
Wind Waves ◽  
Initial Distribution ◽  
Computational Domain ◽  
Model Calculations ◽  
Coastal Slope ◽  
Sediment Volume ◽  
Median Diameter ◽  
Sandy Material

The aim of this work is to study the dynamics of bottom sediments granulometric fractions in the Kalamitsky Gulf coastal zone near the Lake Sakskoe bay-bar under influence of storm surge based on the XBeach numerical morphodynamic model. A series of numerical experiments has been carried out, in which the parameters of waves at the seaward boundary of the computational domain changed in time, simulating the passage of a cyclonic atmospheric anomaly over the investigated region. The initial distribution of the sediment volume concentrations in different parts of the underwater coastal slope profile was set based on the results of field observations. The duration of model calculations was 24 h. The quantitative characteristics of the spatial distribution of various bottom sediments fractions, sediments median diameter and values of bottom deformations were obtained. It has been established that the main morphodynamic changes occurs in the area 0–120 m from the shoreline and are limited by the 3.5 m isobath. It was noted that the maximum changes in the relief of the coastal zone and the upper section of the underwater coastal slope occur during the development and attenuation phases of a storm. In the same time intervals an intensive redistribution of sandy material is observed. It has been established that, with a change in the parameters of wind waves in time at the seaward boundary, the scales of sand material redistribution and deformations of the coastal zone are higher than in the experiment when the direction of the waves does not change with time at the seaward boundary of the computational domain.

VARIABILITY OF THE SUSPENDED SEDIMENT DYNAMICS UNDER IRREGULAR WAVES

2017 ◽  
Author(s):  
Рубен Косян ◽  
Ruben Kosyan ◽  
Boris Divinsky ◽  
Boris Divinsky
Keyword(s):  
Bottom Sediment ◽  
Suspended Sediment ◽  
Frequency Distribution ◽  
Bottom Sediments ◽  
Wave Energy ◽  
Suspended Solids ◽  
Irregular Waves ◽  
Spectral Peak ◽  
Sediment Suspension ◽  
The Impact

The main objective of this paper is an analysis of the impact of the frequency distribution of wave energy on the dynamics of bottom sediment suspension as well as a study of the features of bottom sediments suspension during the passage of waves groups of varying shape and intensity. It is shown that the concentration of wave energy in the primary spectral peak promotes redistribution vertically suspended solids. Laws of suspension within the group are largely determined by the parameters of bottom roughness and the presence (absence) of ripples.

Surface-wave propagation over sinusoidally varying topography

1984 ◽  
Vol 144 ◽  
pp. 419-443 ◽  
Author(s):  
A. G. Davies ◽  
A. D. Heathershaw
Keyword(s):  
Reflection Coefficient ◽  
Surface Waves ◽  
Wave Field ◽  
Incident Wave ◽  
Wave Energy ◽  
Bottom Topography ◽  
Finite Depth ◽  
Linear Perturbation ◽  
Linear Perturbation Theory ◽  
Incident Wave Energy

Surface waves travelling in water of finite depth may be scattered by a region of undulating bottom topography. The present study is concerned with the idealized two-dimensional situation in which long-crested surface waves are incident upon a patch of long-crested regular bottom ripples. The principal question examined concerns the amount of incident wave energy that is reflected by the ripple patch. Linear perturbation theory is used to show that the reflection coefficient is both oscillatory in the quotient of the length of the patch and the surface wavelength, and also strongly dependent upon the quotient of the surface and bed wavelengths. In particular, there is a Bragg resonance between the surface waves and the ripples, which is associated with the reflection of incident wave energy. A secondary question concerns the nature of the wave field in the immediate vicinity of the ripple patch. In resonant cases, it is shown how the partially standing wave on the upwave side of the ripple patch gives way, in an almost linear manner over the patch itself, to a progressive transmitted wave on the downwave side. The theoretical predictions are compared with an extensive set of laboratory observations made in a wave tank. Comparisons relating both to the reflection coefficient, and also to the wave field over the ripple patch, are shown to give consistently good agreement. Finally, the implications of the results for sediment transport on an erodible bed are examined.

Sign in / Sign up

Export Citation Format

Share Document