Hydrodynamic Climate of Port Phillip Bay

This study is dedicated to the hydrodynamic climate of Port Phillip Bay (PPB)—a largest coastal lagoon system in Victoria, Australia. Novelty of the present study includes long-term hydrodynamic hindcast simulations integrated with a spectral wave model. Specifically, a coupled unstructured grid wave–current modelling system (SCHISM + WWM) was built upon a high resolution and advanced wave physics (ST6). This coupling system was thoroughly calibrated and validated against field observations prior to applying for 27-year hindcast and case scenarios. Data from these simulations were then used to investigate the hydrodynamic climate of PPB focusing on three main aspects: water levels, waves and currents. For sea levels, this study shows that tidal and extreme sea levels (storm tides) across a large part of PPB have a similar magnitude. The highest storm tide level is found along eastern coasts of the bay in line with the wind pattern. In the vicinity of the entrance, the extreme sea level slightly reduced, in line with wave decay due to coupling effects. This extreme level is lower than results reported by previous studies, which were not built on a wave–current coupled system. For the wave field, the mean wave direction inside PPB is strongly affected by seasonality, in line with wind patterns. The 100-year return significant wave height is above 2 m along the eastern coasts. At PPH, waves get refracted after passing the narrow entrance. For currents, this study shows that both mean variations and high percentile currents are not affected by seasonality. This highlights the fact that tidal currents dominate flow movements in PPB. However, in extreme conditions, the circulation in PPB is also driven by wind patterns, forming two gyre systems. Based on case scenarios simulations, the strongest magnitude of wind-driven currents is above 0.5 m/s and found in the confined shallow region in the southern portion of PPB.

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Numerical Simulation and Practical Sand Silting in Waterways of Langya Bay

Volume 3: Pipeline and Riser Technology; Ocean Space Utilization ◽

10.1115/omae2008-57860 ◽

2008 ◽

Author(s):

Lin Zhao ◽

Bingchen Liang ◽

Hongda Shi ◽

Xiangzhu Liu

Keyword(s):

Wave Model ◽

Water Levels ◽

Open Boundary ◽

Observation Data ◽

Surface Drag ◽

Time And Space ◽

Sediment Distribution ◽

Waves And Currents ◽

Basin Water ◽

Sediment Model

Dongjiakou Harbor is located at the Langya Bay in the city of Qingdao, Shandong Province. It is a multi-functional harbor of heavy passing capacity under planning in China. The sediment distribution and dispersion in the waterways and harbor basin water areas is of great importance to the construction and operation of the harbor. This article is based on the measurement of waves and currents as well as sediment suspension characteristics on site, and using numerical methods to predict the dispersion and deposition rules in this area. A combined wave-current-sediment model of COHERENS-SED is created through the combination of hydrodynamic model COHERENS and wave model SWAN as well as a sedimentation model SED developed by the authors. Inside COHERENS-SED, SWAN is regarded as a subroutine and it gets time and space varying current velocity and surface elevation from COHERENS. COHERENS gets time and space varying wave relevant parameters calculated by SWAN. Wave-enhanced bottom stress, wave dependent surface drag coefficient and radiation stress are introduced to COHERENS. Then a fully coupled hydrodynamic–sediment model COHERENS-SED accounting for interaction between the waves and currents is obtained and adopted to simulate these hydrodynamic conditions and the sedimentation processes in Langya Bay area. The open boundary of waves and currents is obtained through nesting from running a wider model which includes the Bohai Sea and the North Yellow Sea with coarser solution and contains coastal regions of Shandong Peninsula which includes the whole area of Langya Bay. Generally, the values of time series of current velocities, current directions and water levels as well as sediment concentrations have good agreements with observation data. The study shows the currents in the waterways and harbor basin water areas are relatively weak due to the narrow water width at the port mouth and the current directions parallel to the wharf directions. Also, sediment dispersion scales and strength are predicted according to the computation. The study also estimates the average sediment deposition amount and seabed erosion in this area. Besides, significant wave height and wave period obtained by COHERENS-SWAN shows that simulation result with wave-current interaction is better agreed with the measurement than the case without current.

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Generation of Multivariate Wave Conditions as Input for a Probabilistic Level III Breakwater Design

Volume 4B: Structures, Safety and Reliability ◽

10.1115/omae2014-24143 ◽

2014 ◽

Author(s):

Peter Mercelis ◽

Marc Dufour ◽

Ariel Alvarez Gebelin ◽

Vincent Gruwez ◽

Sarah Doorme ◽

...

Keyword(s):

Water Level ◽

Wind Velocity ◽

Regression Function ◽

Wave Model ◽

Water Levels ◽

Spectral Wave Model ◽

Navigation Channel ◽

Extreme Wind ◽

Wave Conditions ◽

Area Of Concern

For an offshore LNG project situated in the estuary of the Rio de la Plata nearby Montevideo, Uruguay, it was required to verify the deterministic design of the protective rubble mound breakwater and the jetty infrastructure with a level three probabilistic design. Therefore, in first instance extreme site conditions were required both in front of and behind the breakwater. To obtain these conditions, the first step is to extrapolate the offshore variables in order to translate them to the breakwater location. All the possible combinations of extreme wind, water level and waves are quantified with a probability of occurrence. A combination of univariate extreme value distributions, copula’s and regression is used to describe the multivariate statistical behaviour of the offshore variables. The main variable is the wind velocity, as in the area of concern extreme wave conditions are wind driven. The secondary variable is water level. Wind velocity and water levels are only correlated for some wind directions. For these directions, wind velocity and water level extreme value distributions are linked through a multivariate Gumbel Copula. The wave height at the model boundaries was taken into account by a regression function with the extreme wind velocity at the offshore location and the wave period by a regression function with the wave height. This way 1515 synthetic events were selected and simulated with the spectral wave model SWAN, each of which a frequency of occurrence is calculated for. However, due to refraction and diffraction effects of the approach channel (in the area of concern water depths are limited to about 7 m and the navigation channel has a depth of about 14 m), the port basin and the breakwater itself, the spectral wave model SWAN is not sufficient to accurately calculate the local wave conditions in the entire area of interest. Therefore a non-linear Boussinesq wave model (i.e. Mike 21 BW) was set up in addition, using input from the spectral model at the boundary and including the navigation channel of more than 12 km long. Combining both models, significant wave heights are obtained on both the seaward side and the leeside of the breakwater with corresponding frequencies of occurrence. This approach allows the determination of conditional return periods and generates the site conditions required for a probabilistic level three design of the breakwater and the jetty infrastructure taking for example the joint probabilities between waves and water levels fully into account as needed for overtopping or failure calculations.

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Mitigation of Channel Shoaling at a Sheltered Inlet Subject to Flood Gate Operations

Journal of Marine Science and Engineering ◽

10.3390/jmse8110865 ◽

2020 ◽

Vol 8 (11) ◽

pp. 865

Author(s):

Laura Lemke ◽

Matthew S. Janssen ◽

Jon K. Miller

Keyword(s):

Extreme Event ◽

Morphological Changes ◽

Spring Tide ◽

Wave Model ◽

Water Levels ◽

Wave Direction ◽

Real Time Control ◽

Alternative Analysis ◽

Time Control ◽

Hydrodynamic Wave

A comprehensive case study of Keansburg Inlet (New Jersey, USA) is presented with the objective of evaluating inlet management alternatives and assessing the influence of an operational flood gate on channel shoaling. The goal of the research is determining the most effective strategy for minimizing the frequency of maintenance dredging. This study compares the effectiveness of (1) traditional structural solutions; (2) modified dredging templates; and (3) assesses the influence of the flood gate operations during conditions representative of a typical year. Alternative analysis is completed using a coupled hydrodynamic–wave model (Delft3D-Flexible Mesh (FM)) with Real Time Control to simulate morphological changes. The model was calibrated and evaluated using collected field data. Water levels are reproduced within 6% of the spring tide range with lag times less than 20 min. The model results and observations suggest sediment transport is dominated by wave action with pronounced variations in dominant wave direction. The results indicate that changes to the operational dredging, or what the authors have termed broadly as “adaptive dredging techniques”, appear to deliver the most promising improvement. Model results suggest that the current operational procedures of the flood gate do not significantly alter the channel infilling rates and patterns during typical (i.e., non-extreme event) conditions.

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Characteristics and dynamics of crescentic bar events at an open, Mediterranean beach

10.5194/egusphere-egu2020-18730 ◽

2020 ◽

Author(s):

Rinse de Swart ◽

Francesca Ribas ◽

Daniel Calvete ◽

Gonzalo Simarro ◽

Jorge Guillén

Keyword(s):

Visual Analysis ◽

Wave Model ◽

Wave Direction ◽

Geophysical Research ◽

Spectral Wave Model ◽

First Results ◽

Strong Relation ◽

Wave Conditions ◽

Using Data ◽

Bar Formation

Crescentic sand bars have attracted significant attention from coastal scientists during the last decades, which has lead to comparatively good understanding of their formation mechanism, as well as their characteristics and dynamics (e.g. Van Enckevort et al., 2004; Price and Ruessink, 2011). However, the effect of wave obliquity on crescentic bar formation is not yet clear, and processes like coupling of crescentic bars with megacusps deserve further attention. Furthermore, the mechanisms leading to crescentic bar straightening are not well understood. Previously, this was mainly linked to high-energetic wave conditions, but more recent studies (e.g. Price and Ruessink, 2011; Garnier et al., 2013) indicate that this is not always the case. Instead, those studies have found that bar straightening predominantly occurs when the waves are obliquely incident. Finally, there are not many studies of crescentic bars in fetch-limited environments with insignificant tides (such as Mediterranean beaches). Therefore, the objective of the present work is to increase our knowledge on the dynamics of crescentic bars (including bar straightening) using data from an open, Mediterranean beach (Castelldefels beach, 20 km southwest of Barcelona) with hardly any tides and limited fetch.Crescentic bar dynamics have been analysed using a nearly 8-year dataset of time-exposure video images (October 2010 to August 2018). The crescentic bar events, including formation and destruction moments, have been detected using visual analysis. Wave conditions in front of the study site have been collected by propagating 2D spectra (measured by a permanent wave buoy in front of Barcelona harbour) using the SWAN spectral wave model. The first results indicate that there is a lot of morphodynamic variability at the study site, even for low-energetic wave conditions (Hm0 < 0.5 m). Tens of crescentic bar events, including formation, evolution and destruction, can be observed. The bars show a large variation in wavelength (ranging from 100 to 500 m), which is often related to splitting and merging of individual crescents. Furthermore, the results reveal a strong relation between crescentic bar formation and the initial configuration of the bathymetry. Crescentic bars develop often when the sandbar is located some distance from the shoreline, whilst they are hardly observed when the sandbar is located close to the shoreline. Further work (which will be presented at the conference) consists of a detailed analysis of bar characteristics, including their alongshore migration, and the quantification of the role of wave conditions (especially wave direction) on crescentic bar dynamics.References Garnier, R., Falqu&#233;s, A., Calvete, D., Thiebot, J., & Ribas, F. (2013). A mechanism for sandbar straightening by oblique wave incidence. Geophysical Research Letters, 40(11), 2726-2730. Price, T. D., & Ruessink, B. G. (2011). State dynamics of a double sandbar system. Continental Shelf Research, 31(6), 659-674. Van Enckevort, I. M. J., Ruessink, B. G., Coco, G., Suzuki, K., Turner, I. L., Plant, N. G., & Holman, R. A. (2004). Observations of nearshore crescentic sandbars. Journal of Geophysical Research: Oceans, 109(C6).

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Evaluating the accuracy and uncertainty of atmospheric and wave model hindcasts during severe events using model ensembles

Ocean Dynamics ◽

10.1007/s10236-020-01426-9 ◽

2021 ◽

Author(s):

Ali Abdolali ◽

Andre van der Westhuysen ◽

Zaizhong Ma ◽

Avichal Mehra ◽

Aron Roland ◽

...

Keyword(s):

Extreme Event ◽

Numerical Models ◽

Model Performance ◽

Ground Truth ◽

Wave Model ◽

Atmospheric Model ◽

Stationary Source ◽

Source Point ◽

Spectral Wave Model ◽

Model Ensembles

AbstractVarious uncertainties exist in a hindcast due to the inabilities of numerical models to resolve all the complicated atmosphere-sea interactions, and the lack of certain ground truth observations. Here, a comprehensive analysis of an atmospheric model performance in hindcast mode (Hurricane Weather and Research Forecasting model—HWRF) and its 40 ensembles during severe events is conducted, evaluating the model accuracy and uncertainty for hurricane track parameters, and wind speed collected along satellite altimeter tracks and at stationary source point observations. Subsequently, the downstream spectral wave model WAVEWATCH III is forced by two sets of wind field data, each includes 40 members. The first ones are randomly extracted from original HWRF simulations and the second ones are based on spread of best track parameters. The atmospheric model spread and wave model error along satellite altimeters tracks and at stationary source point observations are estimated. The study on Hurricane Irma reveals that wind and wave observations during this extreme event are within ensemble spreads. While both Models have wide spreads over areas with landmass, maximum uncertainty in the atmospheric model is at hurricane eye in contrast to the wave model.

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Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change

Nature Communications ◽

10.1038/s41467-021-22838-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Benjamin H. Strauss ◽

Philip M. Orton ◽

Klaus Bittermann ◽

Maya K. Buchanan ◽

Daniel M. Gilford ◽

...

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

East Coast ◽

The United States ◽

Hurricane Sandy ◽

Water Levels ◽

Anthropogenic Climate Change ◽

Economic Damage ◽

Sea Levels

AbstractIn 2012, Hurricane Sandy hit the East Coast of the United States, creating widespread coastal flooding and over $60 billion in reported economic damage. The potential influence of climate change on the storm itself has been debated, but sea level rise driven by anthropogenic climate change more clearly contributed to damages. To quantify this effect, here we simulate water levels and damage both as they occurred and as they would have occurred across a range of lower sea levels corresponding to different estimates of attributable sea level rise. We find that approximately $8.1B ($4.7B–$14.0B, 5th–95th percentiles) of Sandy’s damages are attributable to climate-mediated anthropogenic sea level rise, as is extension of the flood area to affect 71 (40–131) thousand additional people. The same general approach demonstrated here may be applied to impact assessments for other past and future coastal storms.

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Wave Directions in a Narrow Bay

Journal of Physical Oceanography ◽

10.1175/2009jpo4220.1 ◽

2010 ◽

Vol 40 (1) ◽

pp. 155-169 ◽

Cited By ~ 22

Author(s):

Heidi Pettersson ◽

Kimmo K. Kahma ◽

Laura Tuomi

Keyword(s):

Wave Model ◽

Wave Climate ◽

Spectral Peak ◽

Step Size ◽

Weakly Nonlinear ◽

Spectral Wave Model ◽

Directional Coupling ◽

Directional Wave ◽

The Baltic ◽

The Waves

Abstract In slanting fetch conditions the direction of actively growing waves is strongly controlled by the fetch geometry. The effect was found to be pronounced in the long and narrow Gulf of Finland in the Baltic Sea, where it significantly modifies the directional wave climate. Three models with different assumptions on the directional coupling between the wave components were used to analyze the physics responsible for the directional behavior of the waves in the gulf. The directionally decoupled model produced the direction at the spectral peak correctly when the slanting fetch geometry was narrow but gave a weaker steering than observed when the fetch geometry was broader. The method of Donelan estimated well the direction at the spectral peak in well-defined slanting fetch conditions, but overestimated the longer fetch components during wave growth from a more complex shoreline. Neither the decoupled nor the Donelan model reproduced the observed shifting of direction with the frequency. The performance of the third-generation spectral wave model (WAM) in estimating the wave directions was strongly dependent on the grid resolution of the model. The dominant wave directions were estimated satisfactorily when the grid-step size was dropped to 5 km in the gulf, which is 70 km in its narrowest part. A mechanism based on the weakly nonlinear interactions is proposed to explain the strong steering effect in slanting fetch conditions.

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Wave power assessment in Faroese waters using an oceanic to nearshore scale spectral wave model

Energy ◽

10.1016/j.energy.2021.121404 ◽

2021 ◽

pp. 121404

Author(s):

Bárður Joensen ◽

Bárður A. Niclasen ◽

Harry B. Bingham

Keyword(s):

Wave Model ◽

Wave Power ◽

Spectral Wave Model

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What can idealized storm surge simulations tell us about worst case scenarios?

10.5194/egusphere-egu21-12284 ◽

2021 ◽

Author(s):

Elin Andrée ◽

Jian Su ◽

Martin Drews ◽

Morten Andreas Dahl Larsen ◽

Asger Bendix Hansen ◽

...

Keyword(s):

Wind Speed ◽

Sea Level ◽

North Sea ◽

Wind Direction ◽

Water Levels ◽

Sea Levels ◽

The North ◽

The North Sea ◽

Sea Coast ◽

North Sea Coast

The potential impacts of extreme sea level events are becoming more apparent to the public and policy makers alike. As the magnitude of these events are expected to increase due to climate change, and increased coastal urbanization results in ever increasing stakes in the coastal zones, the need for risk assessments is growing too.The physical conditions that generate extreme sea levels are highly dependent on site specific conditions, such as bathymetry, tidal regime, wind fetch and the shape of the coastline. For a low-lying country like Denmark, which consists of a peninsula and islands that partition off the semi-enclosed Baltic Sea from the North Sea, a better understanding of how the local sea level responds to wind forcing is urgently called for.We here present a map for Denmark that shows the most efficient wind directions for generating extreme sea levels, for a total of 70 locations distributed all over the country&#8217;s coastlines. The maps are produced by conducting simulations with a high resolution, 3D-ocean model, which is used for operational storm surge modelling at the Danish Meteorological Institute. We force the model with idealized wind fields that maintain a fixed wind speed and wind direction over the entire model domain. Simulations are conducted for one wind speed and one wind direction at a time, generating ensembles of a set of wind directions for a fixed wind speed, as well as a set of wind speeds for a fixed wind direction, respectively.For each wind direction, we find that the maximum water level at a given location increases linearly with the wind speed, and the slope values show clear spatial patterns, for example distinguishing the Danish southern North Sea coast from the central or northern North Sea Coast. The slope values are highest along the southwestern North Sea coast, where the passage of North Atlantic low pressure systems over the shallow North Sea, as well as the large tidal range, result in a much larger range of variability than in the more sheltered Inner Danish Waters. However, in our simulations the large fetch of the Baltic Sea, in combination with the funneling effect of the Danish Straits, result in almost as high water levels as along the North Sea coast.Although the wind forcing is completely synthetic with no spatial and temporal structure of a real storm, this idealized approach allows us to systematically investigate the sea level response at the boundaries of what is physically plausible. We evaluate the results from these simulations by comparison to peak water levels from a 58 year long, high resolution ocean hindcast, with promising agreement.

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Numerical Investigation of Hydrodynamics and Cohesive Sediment Transport in Cua Lo and Cua Hoi Estuaries, Vietnam

Journal of Marine Science and Engineering ◽

10.3390/jmse9111258 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1258

Author(s):

Viet Thanh Nguyen ◽

Minh Tuan Vu ◽

Chi Zhang

Keyword(s):

Sediment Transport ◽

Great Influence ◽

Wave Model ◽

Sediment Concentration ◽

Wave Climate ◽

Cohesive Sediment ◽

Wave Direction ◽

The South ◽

The North ◽

Cohesive Sediment Transport

Two-dimensional models of large spatial domain including Cua Lo and Cua Hoi estuaries in Nghe An province, Vietnam, were established, calibrated, and verified with the observed data of tidal level, wave height, wave period, wave direction, and suspended sediment concentration. The model was then applied to investigate the hydrodynamics, cohesive sediment transport, and the morphodynamics feedbacks between two estuaries. Results reveal opposite patterns of nearshore currents affected by monsoons, which flow from the north to the south during the northeast (NE) monsoon and from the south to the north during the southeast (SE) monsoon. The spectral wave model results indicate that wave climate is the main control of the sediment transport in the study area. In the NE monsoon, sediment from Cua Lo port transported to the south generates the sand bar in the northern bank of the Cua Hoi estuary, while sediment from Cua Hoi cannot be carried to the Cua Lo estuary due to the presence of Hon Ngu Island and Lan Chau headland. As a result, the longshore sediment transport from the Cua Hoi estuary to the Cua Lo estuary is reduced and interrupted. The growth and degradation of the sand bars at the Cua Hoi estuary have a great influence on the stability of the navigation channel to Ben Thuy port as well as flood drainage of Lam River.

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