Morphodynamic forecast uncertainty due to bathymetry unknowns

2021 ◽  
Author(s):  
Xavier Sánchez-Artús ◽  
Vicente Gracia ◽  
Manuel Espino Infantes ◽  
Agustín Sánchez-Arcilla Conejo
Keyword(s):  
Surf Zone ◽  
Energy Content ◽  
Numerical Models ◽  
Morphological Evolution ◽  
Morphological Response ◽  
Statistical Characterization ◽  
Morphodynamic Modelling ◽  
Coastal Risks ◽  
Rapid Deployment ◽  
Bathymetric Changes

<p>Operational morphodynamic modelling is becoming an attractive tool for managers to forecast and reduce coastal risks. The development of highly sophisticated numerical models during the last decades has underpinned the simulation of beach morphological evolution due to wave impacts. However, there are still some fundamental aspects, such as the bathymetric uncertainty, that needs to be regularly updated in the modelling chain to avoid a worthless forecast. It is also very well known that the surf zone is the most highly dynamic area although the bathymetry changes between certain limits. In this work, we explore the influence of bathymetric changes in morphodynamic forecasts. XBEACH is used to model the morphological response of a dissipative urban low-lying sandy coastal stretch (Barcelona, Spain) for different forecasted storms to determine the uncertainty bands of predicted coastal erosion and flooding. We consider as benchmarks the results of XBEACH simulations fed with the bathymetric information taken from existing nautical charts. An analysis of the possible beach states of the studied area following the Wright and Short (1984) is later performed to determine a range of topo-bathymetric configurations that will be used to run the model again. These new simulations are used to determine the uncertainty of the erosion and flooding results. The energy content of the storm in terms of intensity and duration uncertainty is also considered in the analysis. The proposed ensemble approach will serve to determine the likelihood of the modelling forecast outputs. Such statistical characterization is aligned with ensemble forecasting in meteo-oceanographic fields and will provide robust information for coastal decision making, for instance when considering proactive rapid deployment measures against a forecasted storm.</p>

scholarly journals A 2D HLL-based weakly coupled model for transient flows on mobile beds

2020 ◽  
Vol 22 (5) ◽  
pp. 1351-1369
Author(s):  
Robin Meurice ◽  
Sandra Soares-Frazão
Keyword(s):  
Numerical Models ◽  
Morphological Evolution ◽  
Coupled Model ◽  
Dam Break ◽  
Water Levels ◽  
Test Cases ◽  
Transient Flows ◽  
Dam Breaks ◽  
Weakly Coupled ◽  
High Interaction

Abstract We propose a finite-volume model that aims at improving the ability of 2D numerical models to accurately predict the morphological evolution of sandy beds when subjected to transient flows like dam-breaks. This model solves shallow water and Exner equations with a weakly coupled approach while the fluxes at the interfaces of the cells are calculated thanks to a lateralized HLLC flux scheme. Besides describing the model, we ran it for four different test cases: a steady flow on an inclined bed leading to aggradation or degradation, a dam-break leading to high interaction between the flow and the bed, a dam-break with a symmetrical enlargement close to the gate and a dam-break in a channel with a 90° bend. The gathered results are discussed and compared to an existing fully coupled approach based on HLLC fluxes. Although both models equally perform regarding water levels, the weakly coupled model looks to better predict the bed evolution for the four test cases. In particular, its results are not affected by an excessive numerical diffusion encountered by the coupled model. Moreover, it usually better estimates the amplitudes of the maximum deposits and scours. It is also more stable when subject to high bed–flow interaction.

scholarly journals Regression Models for Outlier Identification (Hurricanes and Typhoons) in Wave Hindcast Databases

2012 ◽  
Vol 29 (2) ◽  
pp. 267-285 ◽  
Author(s):  
R. Mínguez ◽  
B. G. Reguero ◽  
A. Luceño ◽  
F. J. Méndez
Keyword(s):  
Time Series ◽  
Prediction Models ◽  
Numerical Models ◽  
Wave Climate ◽  
Spatiotemporal Resolution ◽  
Statistical Characterization ◽  
Outlier Identification ◽  
Wave Hindcast ◽  
Spatial Coverage ◽  
Instrumental Records

Abstract The development of numerical wave prediction models for hindcast applications allows a detailed description of wave climate in locations where long-term instrumental records are not available. Wave hindcast databases (WHDBs) have become a powerful tool for the design of offshore and coastal structures, offering important advantages for the statistical characterization of wave climate all over the globe (continuous time series, wide spatial coverage, constant time span, homogeneous forcing, and more than 60-yr-long time series). However, WHDBs present several deficiencies reported in the literature. One of these deficiencies is related to typhoons and hurricanes, which are inappropriately reproduced by numerical models. The main reasons are (i) the difficulty of specifying accurate wind fields during these events and (ii) the insufficient spatiotemporal resolution used. These difficulties make the data related to these events appear as “outliers” when compared with instrumental records. These bad data distort results from calibration and/or correction techniques. In this paper, several methods for detecting the presence of typhoons and/or hurricane data are presented, and their automatic outlier identification capabilities are analyzed and compared. All the methods are applied to a global wave hindcast database and results are compared with existing hurricane and buoy databases in the Gulf of Mexico, Caribbean Sea, and North Atlantic Ocean.

scholarly journals Application of X-Band Wave Radar for Coastal Dynamic Analysis: Case Test of Bagnara Calabra (South Tyrrhenian Sea, Italy)

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Michele Punzo ◽  
Chiara Lanciano ◽  
Daniela Tarallo ◽  
Francesco Bianco ◽  
Giuseppe Cavuoto ◽  
...  
Keyword(s):  
Surf Zone ◽  
Morphological Changes ◽  
Numerical Models ◽  
Wave Number ◽  
Spatial And Temporal Variation ◽  
Tyrrhenian Sea ◽  
Sea State ◽  
Littoral Cell ◽  
X Band ◽  
Wave Radar

Sea state knowledge has a key role in evaluation of coastal erosion, the assessment of vulnerability and potential in coastal zone utilization, and development of numerical models to predict its evolution. X-band radar measurements were conducted to observe the spatial and temporal variation of the sea-state parameters along a 3 km long sandy-gravelly pocket beaches forming a littoral cell on Bagnara Calabra. We produced a sequence of 1000 images of the sea state extending offshore up to 1 mile. The survey has allowed monitoring the coastline, the directional wave spectra, the sea surface current fields, and the significant wave heights and detecting strong rip currents which cause scours around the open inlets and affect the stability of the submerged reef-type breakwaters. The possibility to validate the data acquired with other datasets (e.g., LaMMA Consortium) demonstrates the potential of the X-band radar technology as a monitoring tool to advance the understanding of the linkages between sea conditions, nearshore sediment dynamics, and coastal change. This work proves the possibility to obtain relevant information (e.g., wave number, period, and direction) for evaluation of local erosion phenomena and of morphological changes in the nearshore and surf zone.

scholarly journals Determining the Plio-Quaternary uplift of the southern French massif-Central; a new insights for intraplate orogen dynamics

2019 ◽  
Author(s):  
Oswald Malcles ◽  
Philippe Vernant ◽  
Jean Chéry ◽  
Pierre Camps ◽  
Gaël Cazes ◽  
...  
Keyword(s):  
Numerical Models ◽  
Morphological Evolution ◽  
Vertical Motion ◽  
French Massif Central ◽  
Dynamic Topography ◽  
Active Deformation ◽  
Massif Central ◽  
The North ◽  
Cave System ◽  
Clay Deposits

Abstract. The evolution of intra-plate orogens is still poorly understood. Yet, this is of major importance for understanding the Earth and plate dynamic, as well as the link between surface and deep geodynamic processes. The French Massif Central is an intraplate orogen with a mean elevation of 1000 m, with the highest peak elevations ranging from 1500 m to 1885 m. However, active deformation of the region is still debated due to scarce evidence either from geomorphological or geophysical (i.e. geodesy and seismology) data. Because the Cévennes margin allows the use of karst sediments geochronology and morphometrical analysis, we study the vertical displacements of that region: the southern part of the French Massif-Central. Geochronology and morphometrical results, helped with lithospheric-scale numerical modelling, allow, then, a better understanding of this intraplate-orogen evolution and dynamic. Using the ability of the karst to durably record morphological evolution, we first quantify the incision rates. We then investigate tilting of geomorphological benchmarks by means of a high-resolution DEM. We finally use the newly quantified incision rates to constrain numerical models and compare the results with the geomorphometric study. We show that absolute burial age (10Be/26Al on quartz cobbles) and the paleomagnetic analysis of karstic clay deposits for multiple cave system over a large elevation range correlate consistently. This correlation indicates a regional incision rate of 83.4 +17.3/−5.4 m Ma−1 during the last ca 4 Myrs (Plio-Quaternary). Moreover, we point out through the analysis of 55 morphological benchmarks that the studied region has undergone a regional southward tilting. This tilting is expected as being due to a differential vertical motion between the north and southern part of the studied area. Numerical models show that erosion-induced isostatic rebound can explain up to two-thirds of the regional uplift deduced from dating technics and are consistent with the southward tilting obtain from morphological analysis. We presume that the remaining part is related to dynamic topography or thermal isostasy due to the Massif Central plio-quaternary magmatism.

Pollutant dispersion in the nearshore region: modelling and measurements

1995 ◽  
Vol 32 (9-10) ◽  
pp. 169-178 ◽  
Author(s):  
A. Rodriguez ◽  
A. Sánchez-Arcilla ◽  
J. M. Redondo ◽  
E. Bahia ◽  
J. P. Sierra
Keyword(s):  
Field Model ◽  
Surf Zone ◽  
Initial Conditions ◽  
Numerical Models ◽  
Dispersion Model ◽  
Near Field ◽  
Pollutant Dispersion ◽  
Hydrodynamic Models ◽  
Wave Induced ◽  
Sea Outfalls

Some results on pollutant dispersion modelling and tracer measurements for the Mediterranean Spanish coast are presented. Two hydrodynamic models have been used to simulate wind and wave induced circulation in the nearshore and surf zones respectively. A “near field” model has been used in order to simulate the initial conditions for the local “far field” dispersion model. Two study cases are presented: The first one shows the mixing of conservative tracers in a Mediterranean surf zone from an experimental and numerical models used to predict bacterial dispersion from the main sea outfalls of Barcelona City. The comparison between dye dispersion experiments and model in the surf zone is good, while the outfall predictions show the importance of accurately modelling the effects of buoyancy on the plume.

Use of numerical models to study land-based sedimentation and subsequent nearshore morphological evolution

2008 ◽  
Vol 55 (7-8) ◽  
pp. 601-621 ◽  
Author(s):  
N. Dodd ◽  
A.M. Stoker ◽  
R. Garnier ◽  
G. Vittori ◽  
F. de los Santos ◽  
...  
Keyword(s):  
Numerical Models ◽  
Morphological Evolution

scholarly journals APPLICATION OF NUMERICAL MODELS TO EVALUATE OIL SPILLS PROPAGATION IN THE COASTAL ENVIRONMENT OF THE BLACK SEA

2010 ◽  
Vol 18 (4) ◽  
pp. 288-295 ◽  
Author(s):  
Liliana Rusu
Keyword(s):  
Black Sea ◽  
Surf Zone ◽  
Oil Spills ◽  
Numerical Models ◽  
Model System ◽  
Coastal Environment ◽  
Stokes Drift ◽  
The Black Sea ◽  
Key Factor ◽  
Wave Induced

The last decades continuously increasing of the economical activities in the coastal environment of the Black Sea is obviously leading to the enhancement of the pollution risks due to accidental oil spillages. Starting from the fact that most accidents were generated by an inadequate forecast of the wave conditions, the aim of the present work is to develop a methodology based on spectral phase–averaging wave models able to predict the wave propagation in the coastal environment. The wave induced currents that may be a key factor in driving the pollution are also assessed. This implies both the Stokes drift and the wave induced nearshore currents. The surface streaming effect due to the molecular viscosity was also accounted for. In the nearshore, close to the surf zone, the pollution is usually spread along the coast due to the longshore currents. In this connection, the results of a simple but effective model system called ISSM are also presented. As an alternative simulations with the SHORECIRC model system are also performed. Finally, as a case study, the propagation of the pollution towards the Romanian coast generated by a hypothetic accident at the Gloria drilling platform was assessed. Santrauka Per pastaruosius dešimtmečius pletojant pramone Juodosios jūros priekrantes zonoje, del atsitiktiniu naftos išsiliejimu padidejo taršos rizika. Viena iš priežasčiu, del kuriu ivyksta tokios avarijos, yra netikslios bangu būkles prognozes. Darbo tikslas – remiantis spektriniu fazes vidurkiu apskaičiavimu modeliais, sukurti metodologija, kuri leistu numatyti bangu sklidima priekrantes zonoje. Taip pat ivertinamos bangos sukeltos sroves. Jos gali būti vienas iš pagrindiniu veiksniu, turinčiu itakos teršalu sklidimui jūroje. I skaičiavimus itraukiama Stokso tekme bei bangos sukeltos pakrantes sroves, išreiškiamas paviršiaus sroviu efektas pagal molekuline klampa. Del ilguju pakrantes sroviu prie kranto iš arčiau pavir‐šiaus zonos esančio šaltinio tarša dažniausiai sklinda palei pakrante, todel rezultatai pristatomi taikant modeliavimo siste‐mas ISSM ir SHORECIRC. Modeliuojant remtasi studija, kurioje vertinamas taršos sklidimas ties Rumunijos pakrante del spejamai ivykusios avarijos Glorijos grežinio platformoje. Резюме Постоянно увеличивающаяся в последние десятилетия экономическая активность в прибрежной зоне Чѐрного моря ведѐт к бóльшему риску загрязнения из-за случайных разливов нефти. В связи с тем, что большая часть случаев разлива была связана с неадекватным прогнозом волнения, целью настоящей работы было разработать методологию, основанную на спектральных моделях волнения с усреднением фазы, способную предсказывать распространение волн в прибрежной зоне. Было оценено также течение, вызванное волнением, которое может стать решающим фактором в распространении загрязнения. Оно включает в себя стоксово дрейфовое течение и прибрежное течение. Учтено также поверхностное течение, вызываемое ветром через касательные напряжения. В качестве примера рассмотрено распространение в направлении румынского берега загрязнения, вызванного гипотетической аварией на буровой платформе Глория.

Analysis of Electromigration- and Stress-Induced Dynamical Response of Voids Confined in Metallic Thin Films

2005 ◽  
Vol 899 ◽  
Author(s):  
M. Rauf Gungor ◽  
Jaeseol Cho ◽  
Dimitrios Maroudas
Keyword(s):  
Thin Films ◽  
Electrical Resistance ◽  
Morphological Evolution ◽  
Dynamical Response ◽  
Metallic Thin Films ◽  
Morphological Response ◽  
Periodic Response ◽  
Void Migration ◽  
Interconnect Lines ◽  
Time Periodic

AbstractA theoretical analysis based on self-consistent dynamical simulations is presented of electromigration- and stress-induced surface morphological response of voids confined in metallic thin films. The analysis predicts the onset of stable time-periodic states for the void surface morphological response, which is associated with current-driven wave propagation on the void surface. This time-periodic response is demonstrated under certain electromigration conditions and detailed response diagrams are presented which map the corresponding parameter space to regions of steady, time-periodic, and unstable surface morphological response. The evolution of the electrical resistance of these thin films also is computed, providing an interpretation for experimentally observed time-periodic response of the electrical resistance of metallic interconnect lines on the basis of current-driven void morphological evolution. In addition, we demonstrate significant effects on the electromigration-induced morphologically stable void migration of mechanical stress application in a metallic thin film. Specifically, we find that under certain electromechanical conditions, elastic stress can cause substantial retardation of void motion, as measured by the constant speed of electromigration-induced translation of morphologically stable voids. More importantly, this effect suggests the possibility for complete inhibition of void motion under stress.

scholarly journals INFLUENCE OF THE WAVE REGIME IN COASTAL SEDIMENT BUDGET: PRESENT AND FUTURE SCENARIOS

2012 ◽  
Vol 1 (33) ◽  
pp. 85
Author(s):  
Sandra Plecha ◽  
Carina L. Lopes ◽  
Nicolas Bruneau ◽  
Nuno A. Ribeiro ◽  
Paulo A. Silva ◽  
...  
Keyword(s):  
Correlation Coefficients ◽  
Sediment Budget ◽  
Wave Regime ◽  
Regime Changes ◽  
Morphodynamic Modelling ◽  
Coastal Systems ◽  
Anticlockwise Rotation ◽  
The Future ◽  
Bathymetric Changes

The wave regime has a strong influence on the sediment transport in coastal systems. Modifications in wave regime induced by climate changes can influence the sediment dynamics of those coastal systems. To access wave regime changes it is crucial to analyse the future modifications in the wave height, period and direction. This work aims to analyse the influence of a future wave regime in the sediment budget of a coastal lagoon inlet and at the nearshore adjacent coast. To achieve this goal a morphodynamic modelling system was used, forced by present and future waves, corresponding to a typical year of present and future wave climates. A methodology to determine a typical year of each climate was developed based on the determination of correlation coefficients between each climate and corresponding year data. The comparison between present and future wave climates evidences that wave period and height are in general similar for both climates, and confirms the anticlockwise rotation of waves in the future. The morphodynamic simulations revealed analogous results for both wave climates, resulting in similar patterns for the residual sediment fluxes, but slightly more intense in the present. The consequent bathymetric changes show that the deposition trend presently observed offshore the inlet tends to increase for future waves climate. The transport budgets were also analysed for both wave regimes, evidencing that the alongshore transport slightly decreases (~1%) for future waves.

scholarly journals LONGSHORE CURRENTS DUE TO SURF ZONE BARRIER

1978 ◽  
Vol 1 (16) ◽  
pp. 44
Author(s):  
R. Bettess ◽  
C.A. Fleming ◽  
J.C. Heinrich ◽  
O.C. Zienkiewicz ◽  
D.I. Austin
Keyword(s):  
Sediment Transport ◽  
Stream Function ◽  
Water Intake ◽  
Surf Zone ◽  
Numerical Models ◽  
Cooling Water ◽  
Radiation Stress ◽  
Longshore Currents ◽  
Set Up ◽  
Incident Waves

We consider a straight coastline exposed to large regular waves, of typical wave length, 100 m amplitude 1.6 m, and period 12 sec. The radiation stress gradients in the extensive (up to 2 km wide) surf zone cause set up and long-shore currents. Despite these currents, the beach is known to be fairly stable. If now a cooling water intake basin is introduced on the coast, it is required to determine first whether the wave induced currents in the vicinity of the basin will affect the circulation of cooling water and second, whether sediment transport will occur, leading to a dredging requirement for the basin. An extensive programme of physical model testing and numerical studies is being undertaken, in order to answer the above questions, and this paper will survey the progress made to date. At the 15th Coastal Engineering Conference a paper on the application of a mathematical model to the prediction of dredging properties inside a cooling water intake basin was 9 presented by Fleming and Hunt, which described the first stage of this work . - In that paper a sediment transport model was combined interactively with numerical models of wave refraction, wave diffraction, long shore currents and circulation currents. The last of these numerical models was used to evaluate the current patterns due to the interruption of the continuity of the longshore currents, together with the cooling water flows in the vicinity of the basin. In this paper we describe the development of more sophisticated numerical models for the first three stages of the process. An understanding of the process of longshore current and set up creation, depends on the concept of radiation stress, introduced by Longuet-Higgins and Stewart,12'13' ' in a series of papers. A number of workers have since used the radiation stress to determine coastline phenomena, and we now describe a few of the relevant papers, without any attempt at a comprehensive survey. Bowen 5'6 considered a straight coastline with parallel contours, and determined near shore circulation patterns, using a stream function formulation of the shallow water equations, for normally incident waves, with a sinusoidal coastwise variation in wave amplitude. He used a finite difference method to solve for the stream function. Longuet-Higgins10'11 criticized Bowen's use of a constant mixing length (horizontal) viscosity, and introduced a viscosity which varied directly with the distance from the shore, in his one dimensional analytical model for obliquely incident waves. He was able to obtain analytically longshore velocity profiles, which he plotted for a range of viscosities.

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