Journal of Marine Science and Engineering

26 pages, 6068 KiB

Open AccessEditor’s ChoiceArticle

Research on Position Sensorless Control of RDT Motor Based on Improved SMO with Continuous Hyperbolic Tangent Function and Improved Feedforward PLL

by Hongfen Bai, Bo Yu and Wei Gu

J. Mar. Sci. Eng. 2023, 11(3), 642; https://doi.org/10.3390/jmse11030642 - 17 Mar 2023

Cited by 18 | Viewed by 1862

Abstract

With the increasing use of electric propulsion ships, the emergence of the shaftless rim-driven thruster (RDT) as a revolutionary integrated motor thruster is gradually becoming an important development direction for green ships. The shaftless structure of RDTs leads to their dependence on position [...] Read more.

With the increasing use of electric propulsion ships, the emergence of the shaftless rim-driven thruster (RDT) as a revolutionary integrated motor thruster is gradually becoming an important development direction for green ships. The shaftless structure of RDTs leads to their dependence on position sensorless control techniques. In this study, a novel control algorithm using a composite sliding mode observer (SMO) with a modified feed-forward phase-locked loop (PLL) is presented for achieving high accuracy position and speed control of shaftless RDT motors. The deviation between the observed and actual currents is exploited to develop a current SMO to extract back electromotive force (back-EMF) errors. On this basis, a back-EMF observer is established to achieve accurate estimation of the back-EMF. The basic structure of the PLL was modified and incorporates a speed feedforward mechanism, which enhances the performance of rotor position estimation and facilitates bidirectional rotation. The stability of the algorithm has been verified in Matlab/Simulink for a range of steady-state, dynamic, and ship propeller loading conditions. Remarkably, the control algorithm boasts an impressive adjustment time of approximately 0.006 s and its position estimation error may be as low as 0.03 rad. Simulation results highlight the performance of the algorithm to achieve bidirectional rotation, while exhibiting fast convergence, minimal vibration, exceptional control accuracy, and robustness. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Maritime Transportation)

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25 pages, 18299 KiB

Open AccessEditor’s ChoiceArticle

New Methodology for Shoreline Extraction Using Optical and Radar (SAR) Satellite Imagery

by Sara Zollini, Donatella Dominici, Maria Alicandro, María Cuevas-González, Eduard Angelats, Francesca Ribas and Gonzalo Simarro

J. Mar. Sci. Eng. 2023, 11(3), 627; https://doi.org/10.3390/jmse11030627 - 16 Mar 2023

Cited by 12 | Viewed by 3394

Abstract

Coastal environments are dynamic ecosystems, constantly subject to erosion/accretion processes. Erosional trends have unfortunately been intensifying for decades due to anthropic factors and an accelerated sea level rise might exacerbate the problem. It is crucial to preserve these areas for safeguarding not only [...] Read more.

Coastal environments are dynamic ecosystems, constantly subject to erosion/accretion processes. Erosional trends have unfortunately been intensifying for decades due to anthropic factors and an accelerated sea level rise might exacerbate the problem. It is crucial to preserve these areas for safeguarding not only coastal ecosystems and cultural heritage, but also the population living there. In this context, monitoring coastal areas is essential and geomatics techniques, especially satellite remote sensing imagery, might prove very advantageous. In this paper, a semi-automatic methodology to extract shorelines from SAR (Synthetic Aperture Radar) Sentinel-1 and optical Sentinel-2 satellite images was developed. An experimental algorithm, called J-Net Dynamic, was tested in two pilot sites. The semi-automatic methodology was validated with GNSS (Global Navigation Satellite System) reference shorelines and demonstrated to be a powerful tool for a robust extraction of the shoreline both from optical and SAR images. The experimental algorithm was able to extract the shoreline closer to the reference with SAR images on the natural beach of Castelldefels and it was demonstrated to be less sensitive to speckle effects than the commonly used Canny Edge Detector. Using the SAR images of the urban beach of Somorrostro, the Canny detector was not able to extract the shoreline, while the new algorithm could do it but with low accuracy because of the noise induced by man-made structures. For further investigation, the Sentinel-2-extracted shorelines were also compared to the ones extracted by a state-of-the-art tool, CoastSat, in the two beaches using both automatic and manual thresholds. The mean errors obtained with J-Net Dynamic were generally higher than the ones from CoastSat using the manual threshold but lower if using the automatic one. The proposed methodology including the J-Net Dynamic algorithm proves to extract the shorelines closer to the reference in most of the cases and offers the great advantage of being able to work with both optical and SAR images. This feature could allow to reduce the time lag between satellite derived shorelines paving the way to an enhanced monitoring and management of coastal areas. Full article

(This article belongs to the Special Issue Remote Sensing for Coastal Management)

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14 pages, 5525 KiB

Open AccessEditor’s ChoiceArticle

Image Dataset for Neural Network Performance Estimation with Application to Maritime Ports

by Miro Petković, Igor Vujović, Zvonimir Lušić and Joško Šoda

J. Mar. Sci. Eng. 2023, 11(3), 578; https://doi.org/10.3390/jmse11030578 - 8 Mar 2023

Cited by 4 | Viewed by 2818

Abstract

Automated surveillance systems based on machine learning and computer vision constantly evolve to improve shipping and assist port authorities. The data obtained can be used for port and port property surveillance, traffic density analysis, maritime safety, pollution assessment, etc. However, due to the [...] Read more.

Automated surveillance systems based on machine learning and computer vision constantly evolve to improve shipping and assist port authorities. The data obtained can be used for port and port property surveillance, traffic density analysis, maritime safety, pollution assessment, etc. However, due to the lack of datasets for video surveillance and ship classification in real maritime zones, there is a need for a reference dataset to compare the obtained results. This paper presents a new dataset for estimating detection and classification performance which provides versatile ship annotations and classifications for passenger ports with a large number of small- to medium-sized ships that were not monitored by the automatic identification system (AIS) and/or the vessel traffic system (VTS). The dataset is considered general for the Mediterranean region since many ports have a similar maritime traffic configuration as the Port of Split, Croatia. The dataset consists of 19,337 high-resolution images with 27,849 manually labeled ship instances classified into 12 categories. The vast majority of the images contain the port and starboard sides of the ships. In addition, the images were acquired in a real maritime zone at different times of the year, day, weather conditions, and sea state conditions. Full article

(This article belongs to the Section Ocean Engineering)

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19 pages, 17413 KiB

Open AccessEditor’s ChoiceArticle

Past Analogues of Deoxygenation Events in the Mediterranean Sea: A Tool to Constrain Future Impacts

by Alan Maria Mancini, Giacomo Bocci, Caterina Morigi, Rocco Gennari, Francesca Lozar and Alessandra Negri

J. Mar. Sci. Eng. 2023, 11(3), 562; https://doi.org/10.3390/jmse11030562 - 6 Mar 2023

Cited by 6 | Viewed by 2246

Abstract

Human-induced carbon emissions are altering the modern climate, with severe repercussions on ecosystems. Among others, anthropogenic pressure is causing deoxygenation of the bottom water, with the widespread establishment of hypoxic zones in several Mediterranean areas. The geological archives allow investigating past deoxygenation dynamics [...] Read more.

Human-induced carbon emissions are altering the modern climate, with severe repercussions on ecosystems. Among others, anthropogenic pressure is causing deoxygenation of the bottom water, with the widespread establishment of hypoxic zones in several Mediterranean areas. The geological archives allow investigating past deoxygenation dynamics (sapropel events) and their impact on marine ecosystems. Here, we compare the causes and the evolution of deoxygenation dynamics which occurred during two different time periods (Messinian and Holocene) in different paleoceanographic settings based on their micropaleontological content. The Messinian sapropel events are the result of increased export productivity during a relatively cold and arid context, triggering bottom anoxic conditions. The Holocene sapropel formed in response to weakening/stopping of the thermohaline circulation due to increasing temperature and freshwater input. Our results suggest that the deoxygenation dynamics in the Mediterranean in the near future will not follow the trend characteristic of the Holocene deep-sea sapropel because of the predicted drying trend. Differently, the paleoceanographic setting triggering the Messinian shallow-sea sapropels is comparable with the modern situation in different Mediterranean areas, where human-induced eutrophication is promoting deoxygenation. Based on these results, we suggest that the patchy deoxygenation trend in the Mediterranean Sea caused by climate warming may lead to a drastic change in the ecosystem services which would likely impact human activities. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series “Paleoecology and Paleoenvironment Reconstruction”)

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22 pages, 3038 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Proposal of Zero-Emission Tug in South Korea Using Fuel Cell/Energy Storage System: Economic and Environmental Long-Term Impacts

by Kyunghwa Kim, Kido Park, Gilltae Roh, Choungho Choung, Kyuhyeong Kwag and Wook Kim

J. Mar. Sci. Eng. 2023, 11(3), 540; https://doi.org/10.3390/jmse11030540 - 2 Mar 2023

Cited by 2 | Viewed by 2383

Abstract

This study presents the results of economic and environmental analysis for two types of zero-emission ships (ZESs) that are receiving more attention to meet strengthened environmental regulations. One of the two types of ZES is the ZES using only the energy storage system [...] Read more.

This study presents the results of economic and environmental analysis for two types of zero-emission ships (ZESs) that are receiving more attention to meet strengthened environmental regulations. One of the two types of ZES is the ZES using only the energy storage system (All-ESS), and the other is the ZES with fuel cell and ESS hybrid system (FC–ESS). The target ship is a tug operating in South Korea, and the main parameters are based on the specific circumstances of South Korea. The optimal capacity of the ESS for each proposed system is determined using an optimization tool. The total cost for a ship’s lifetime is calculated using economic analysis. The greenhouse gas (GHG) emission for the fuel’s lifecycle (well-to-wake) is calculated using environmental analysis. The results reveal that the proposed ZESs are 1.7–3.4 times more expensive than the conventional marine gas oil (MGO)-fueled ship; however, it could be reduced by 1.3–2.4 times if the carbon price is considered. The proposed ZESs have 58.7–74.3% lower lifecycle GHG emissions than the one from the conventional ship. The results also highlight that the electricity- or hydrogen-based ZESs should reduce GHG emissions from the upstream phase (well-to-tank) to realize genuine ZESs. Full article

(This article belongs to the Special Issue Decarbonization of Ship Power Plants)

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24 pages, 1700 KiB

Open AccessEditor’s ChoiceArticle

Trajectory Tracking Nonlinear Controller for Underactuated Underwater Vehicles Based on Velocity Transformation

by Przemyslaw Herman

J. Mar. Sci. Eng. 2023, 11(3), 509; https://doi.org/10.3390/jmse11030509 - 26 Feb 2023

Cited by 6 | Viewed by 1345

Abstract

This paper proposes an algorithm that performs the task of tracking the desired trajectory for underactuated marine vehicles (primarily underwater) that move horizontally. The control scheme, which takes into account model inaccuracies and external disturbances, was designed using the quantities obtained after the [...] Read more.

This paper proposes an algorithm that performs the task of tracking the desired trajectory for underactuated marine vehicles (primarily underwater) that move horizontally. The control scheme, which takes into account model inaccuracies and external disturbances, was designed using the quantities obtained after the transformation of the dynamic equations of motion resulting from the decomposition of the inertia matrix. This, in turn, led to the equation of dynamics with a diagonal inertia matrix. A specific feature of the offered controller is its dual role. It not only allows tracking the desired trajectory, but at the same time, makes it possible to estimate the impact of dynamic couplings when the vehicle is in motion. Such an approach to the tracking task is important at the initial design stage when the choice of the control algorithm has not yet been decided and experimental tests have not been performed. This is feasible because the new variables after the velocity transformation include not only vehicle parameters, but also actual velocities and forces. Therefore, it is also possible to track the original variables. The theoretical results were followed up with simulation tests conducted on a model with three degrees of freedom for two underwater vehicles. Full article

(This article belongs to the Special Issue Advances in Marine Vehicles, Automation and Robotics)

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14 pages, 1861 KiB

Open AccessEditor’s ChoiceArticle

UMGAN: Underwater Image Enhancement Network for Unpaired Image-to-Image Translation

by Boyang Sun, Yupeng Mei, Ni Yan and Yingyi Chen

J. Mar. Sci. Eng. 2023, 11(2), 447; https://doi.org/10.3390/jmse11020447 - 17 Feb 2023

Cited by 19 | Viewed by 3191

Abstract

Due to light absorption and scattering underwater images suffer from low contrast, color distortion, blurred details, and uneven illumination, which affect underwater vision tasks and research. Therefore, underwater image enhancement is of great significance in vision applications. In contrast to existing methods for [...] Read more.

Due to light absorption and scattering underwater images suffer from low contrast, color distortion, blurred details, and uneven illumination, which affect underwater vision tasks and research. Therefore, underwater image enhancement is of great significance in vision applications. In contrast to existing methods for specific underwater environments or reliance on paired datasets, this study proposes an underwater multiscene generative adversarial network (UMGAN) to enhance underwater images. The network implements unpaired image-to-image translation between the underwater turbid domain and the underwater clear domain. It has a great enhancement impact on several underwater image types. Feedback mechanisms and a noise reduction network are designed to optimize the generator and address the issue of noise and artifacts in GAN-produced images. Furthermore, a global–local discriminator is employed to improve the overall image while adaptively modifying the local region image effect. It resolves the issue of over- and underenhancement in local regions. The reliance on paired training data is eliminated through a cycle consistency network structure. UMGAN performs satisfactorily on various types of data when compared quantitatively and qualitatively to other state-of-the-art algorithms. It has strong robustness and can be applied to various enhancement tasks in different scenes. Full article

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17 pages, 3099 KiB

Open AccessEditor’s ChoiceArticle

Discerning Discretization for Unmanned Underwater Vehicles DC Motor Control

by Jovan Menezes and Timothy Sands

J. Mar. Sci. Eng. 2023, 11(2), 436; https://doi.org/10.3390/jmse11020436 - 16 Feb 2023

Cited by 9 | Viewed by 2641

Abstract

Discretization is the process of converting a continuous function or model or equation into discrete steps. In this work, learning and adaptive techniques are implemented to control DC motors that are used for actuating control surfaces of unmanned underwater vehicles. Adaptive control is [...] Read more.

Discretization is the process of converting a continuous function or model or equation into discrete steps. In this work, learning and adaptive techniques are implemented to control DC motors that are used for actuating control surfaces of unmanned underwater vehicles. Adaptive control is a strategy wherein the controller is designed to adapt the system with parameters that vary or are uncertain. Parameter estimation is the process of computing the parameters of a system using a model and measured data. Adaptive methods have been used in conjunction with different parameter estimation techniques. As opposed to the ubiquitous stochastic artificial intelligence approaches, very recently proposed deterministic artificial intelligence, a learning-based approach that uses the physics-defined process dynamics, is also applied to control the output of the DC motor to track a specified trajectory. This work goes further to evaluate the performance of the adaptive and learning techniques based on different discretization methods. The results are evaluated based on the absolute error mean between the output and the reference trajectory and the standard deviation of the error. The first-order hold method of discretization and surprisingly large sample time of seven-tenths of a second yields greater than sixty percent improvement over the results presented in the prequel literature. Full article

(This article belongs to the Special Issue Autonomous Underwater Vehicle Technology Advances in Ocean Observation)

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25 pages, 12570 KiB

Open AccessEditor’s ChoiceArticle

Optimal SOC Control and Rule-Based Energy Management Strategy for Fuel-Cell-Based Hybrid Vessel including Batteries and Supercapacitors

by Zeyu Ma, Hao Chen, Jingang Han, Yizheng Chen, Jiongchen Kuang, Jean-Frédéric Charpentier, Nadia Aϊt-Ahmed and Mohamed Benbouzid

J. Mar. Sci. Eng. 2023, 11(2), 398; https://doi.org/10.3390/jmse11020398 - 10 Feb 2023

Cited by 11 | Viewed by 2105

Abstract

Around the world, the development of electric vehicles is underway, including in maritime transportation. However, the development of clean energy vessels still has a long way to go. Fuel cells (FCs) are a relevant choice among the many clean energy sources to power [...] Read more.

Around the world, the development of electric vehicles is underway, including in maritime transportation. However, the development of clean energy vessels still has a long way to go. Fuel cells (FCs) are a relevant choice among the many clean energy sources to power clean energy vessels. However, due to the complex and drastic change in the shipload power, FCs need to be equipped with dynamic fast-response energy storage equipment to make up for it. For multiple energy storage devices connected in parallel, the state of charge (SOC) is not balanced, which affects their service life and the stability of the vessel microgrid, as well as slowing the speed and lowering the accuracy of SOC equalization. This paper proposes a distributed variable sag slope control strategy for vessels to improve SOC equalization, with a FC as the energy source and a battery and supercapacitor as the energy storage system (ESS). For the output power distribution problem of energy storage equipment caused by shipload power variation, a power distribution strategy with a variable filter time constant is used to improve the reasonableness of the output power distribution of energy-based lithium batteries and power-based supercapacitors. Meanwhile, this paper considers the power generation equipment’s service life and energy cost as the optimization objectives, considering the discharge depth of the energy storage equipment. Finally, a method based on the combination of the lithium battery SOC rule (the rule formulated according to the state of charge and load power change in energy storage equipment) and particle swarm optimization algorithm is proposed to solve this problem. The simulation results show that the proposed strategy improves the equalization speed and accuracy of the SOC of energy storage devices, fully realizes the characteristics of different energy storage devices, and reduces the life loss of energy storage devices. Full article

(This article belongs to the Special Issue Advanced Research in Innovative Ship Energy Systems)

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12 pages, 3230 KiB

Open AccessEditor’s ChoiceArticle

Stress–Strain Assessment of Honeycomb Sandwich Panel Subjected to Uniaxial Compressive Load

by Pasqualino Corigliano, Giulia Palomba, Vincenzo Crupi and Yordan Garbatov

J. Mar. Sci. Eng. 2023, 11(2), 365; https://doi.org/10.3390/jmse11020365 - 6 Feb 2023

Cited by 6 | Viewed by 1982

Abstract

The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the [...] Read more.

The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the structural integrity, economy, safety and environmentally friendly design of the ship’s hull structure. A new design solution may be represented by aluminium alloy honeycomb sandwich structures, both as plane panels or stiffened ones, which are characterised by excellent impact-absorption capabilities and a high stiffness-to-weight ratio. Still, their response to some conditions typical of ship structural design needs to be deeply investigated. Axial compressive loading is one of the most critical conditions that could impact the structural integrity of such light-weight solutions. Hence, the uniaxial compressive behaviour of aluminium honeycomb sandwich structures has to be deeply investigated to promote their integration in ship structural design. Within this context, the present work performs an experimental and numerical study of a honeycomb sandwich panel subjected to uniaxial compressive loads. The results will help develop models for predicting the uniaxial compressive load-carrying capacity of hybrid honeycomb sandwiches of aluminium alloy design. Full article

(This article belongs to the Special Issue Lightweight and Additively Manufactured Structures in Marine Applications)

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13 pages, 13408 KiB

Open AccessEditor’s ChoiceArticle

Sediment Erosion Generated by a Coandă-Effect-Based Polymetallic-Nodule Collector

by Said Alhaddad and Rudy Helmons

J. Mar. Sci. Eng. 2023, 11(2), 349; https://doi.org/10.3390/jmse11020349 - 4 Feb 2023

Cited by 15 | Viewed by 1927

Abstract

To date, hydraulic collection is the most widely considered technology in polymetallic-nodule mining, since there is no direct contact between hydraulic collectors and ocean floor. To construct a hydraulic collector that results in the least sediment disturbance, it is critical to develop an [...] Read more.

To date, hydraulic collection is the most widely considered technology in polymetallic-nodule mining, since there is no direct contact between hydraulic collectors and ocean floor. To construct a hydraulic collector that results in the least sediment disturbance, it is critical to develop an insightful understanding of the interaction between the collector and sediment bed. To this end, we conducted a set of small-scale experiments in which several operational conditions were tested, delivering the first quantitative data for sediment erosion resulting from a hydraulic collector driving over a sand bed. This paper presents and discusses the experimental results and observations. It is found that the collector’s forward velocity is inversely proportional to the bed-sediment erosion depth, since the bed is exposed to the flow for a longer time when the collector drives slower and vice versa. In contrast, an increased jet velocity leads to a larger erosion depth. Furthermore, when the collector underside is nearer to the sediment bed, a larger sediment layer is exposed to the water flow, resulting in a larger erosion depth. Finally, the experimental results show that collector water jets strike the sediment bed under an inclined angle, destabilizing the upper sediment layer and consequently dragging sediment particles along toward the collection duct and behind the collector head. This study improves the predictability of sediment erosion created by Coandă-effect-based collectors, which is a crucial asset to optimize the collector design and decrease the extent of the associated sediment plumes. Full article

(This article belongs to the Section Ocean Engineering)

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38 pages, 2639 KiB

Open AccessEditor’s ChoiceReview

Reconstruction Methods in Oceanographic Satellite Data Observation—A Survey

by Leon Ćatipović, Frano Matić and Hrvoje Kalinić

J. Mar. Sci. Eng. 2023, 11(2), 340; https://doi.org/10.3390/jmse11020340 - 3 Feb 2023

Cited by 6 | Viewed by 1828

Abstract

Oceanographic parameters, such as sea surface temperature, surface chlorophyll-a concentration, sea surface ice concentration, sea surface height, etc., are listed as Essential Climate Variables. Therefore, there is a crucial need for persistent and accurate measurements on a global scale. While in situ methods [...] Read more.

Oceanographic parameters, such as sea surface temperature, surface chlorophyll-a concentration, sea surface ice concentration, sea surface height, etc., are listed as Essential Climate Variables. Therefore, there is a crucial need for persistent and accurate measurements on a global scale. While in situ methods tend to be accurate and continuous, these qualities are difficult to scale spatially, leaving a significant portion of Earth’s oceans and seas unmonitored. To tackle this, various remote sensing techniques have been developed. One of the more prominent ways to measure the aforementioned parameters is via satellite spacecraft-mounted remote sensors. This way, spatial coverage is considerably increased while retaining significant accuracy and resolution. Unfortunately, due to the nature of electromagnetic signals, the atmosphere itself and its content (such as clouds, rain, etc.) frequently obstruct the signals, preventing the satellite-mounted sensors from measuring, resulting in gaps—missing data—in satellite recordings. One way to deal with these gaps is via various reconstruction methods developed through the past two decades. However, there seems to be a lack of review papers on reconstruction methods for satellite-derived oceanographic variables. To rectify the lack, this paper surveyed more than 130 articles dealing with the issue of data reconstruction. Articles were chosen according to two criteria: (a) the article has to feature satellite-derived oceanographic data (b) gaps in satellite data have to be reconstructed. As an additional result of the survey, a novel categorising system based on the type of input data and the usage of time series in reconstruction efforts is proposed. Full article

(This article belongs to the Special Issue Recent Scientific Developments in Ocean Observation)

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24 pages, 15787 KiB

Open AccessEditor’s ChoiceArticle

Influence of Wave–Current Interaction on a Cyclone-Induced Storm Surge Event in the Ganges–Brahmaputra–Meghna Delta: Part 1—Effects on Water Level

by Md Wasif E Elahi, Xiao Hua Wang, Julio Salcedo-Castro and Elizabeth A. Ritchie

J. Mar. Sci. Eng. 2023, 11(2), 328; https://doi.org/10.3390/jmse11020328 - 2 Feb 2023

Cited by 6 | Viewed by 2279

Abstract

The Ganges–Brahmaputra–Meghna Delta (GBMD) located in the head of the Bay of Bengal is regularly affected by severe tropical cyclones frequently. The GBMD covers the Bangladesh coast, which is one of the most vulnerable areas in the world due to cyclone-induced storm surges. [...] Read more.

The Ganges–Brahmaputra–Meghna Delta (GBMD) located in the head of the Bay of Bengal is regularly affected by severe tropical cyclones frequently. The GBMD covers the Bangladesh coast, which is one of the most vulnerable areas in the world due to cyclone-induced storm surges. More than 30% of the total country’s population lives on the Bangladesh coast. Hence, it is crucial to understand the underlying processes that modulate the storm surge height in the GBMD. A barotropic numerical 3D model setup is established by using Delft3D and SWAN to investigate a cyclone-induced storm surge event. The model is calibrated and validated for Cyclone Sidr in 2007 and applied to six idealized cyclonic scenarios. Numerical experiments with different coupling configurations are performed to distinguish the contribution of wind, tides, waves, and wave–current interactions (WCI) on the storm surge height. Results show that the wind-driven setup is the dominant contributor to the storm surge height during cyclonic events. Based on the tidal phase and wind direction, the interaction between tide and wind can increase or decrease the magnitude of the storm surge height. Finally, considering the wind-driven wave may increase the surge height up to 0.3 m along the coastline through a strong wave setup. Full article

(This article belongs to the Special Issue Numerical Modelling of Atmospheres and Oceans)

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21 pages, 3963 KiB

Open AccessEditor’s ChoiceReview

Southern Ocean Iron Limitation of Primary Production between Past Knowledge and Future Projections

by Emma Bazzani, Chiara Lauritano and Maria Saggiomo

J. Mar. Sci. Eng. 2023, 11(2), 272; https://doi.org/10.3390/jmse11020272 - 25 Jan 2023

Cited by 7 | Viewed by 3095

Abstract

Primary production in the Southern Ocean highly depends on phytoplankton and has been reported to be limited by the availability of the micronutrient iron. The aim of this review is to summarize the past and current knowledge on iron limitation in the Southern [...] Read more.

Primary production in the Southern Ocean highly depends on phytoplankton and has been reported to be limited by the availability of the micronutrient iron. The aim of this review is to summarize the past and current knowledge on iron limitation in the Southern Ocean, and specifically how it affects primary producers, thus influencing the whole Southern Ocean community structure, carbon cycling, and large-scale ocean biogeochemistry. In this region, extensive variability exists between different areas regarding iron availability, but also between seasons. Moreover, co-limitations with other abiotic environmental factors exist, further complicating the assessment of the role of iron as limiting factor for phytoplankton productivity. Currently, climate change is altering the Southern Ocean environment. How these changes will affect resident phytoplankton is still not clear, possibly modifying the iron supply mechanisms. Existing projections point towards a possible partial relief of iron stress on phytoplankton, but the interactions between different environmental changes, and the cascade effects they will have, are still poorly understood, and some aspects understudied. Here we try to synthetize the available predictions and uncertainties concerning this topic. Full article

(This article belongs to the Special Issue Biodiversity, Adaptation Strategies, and Opportunities in Extreme Marine Environments)

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15 pages, 4650 KiB

Open AccessEditor’s ChoiceArticle

Intelligent Model for Dynamic Shear Modulus and Damping Ratio of Undisturbed Marine Clay Based on Back-Propagation Neural Network

by Qi Wu, Zifan Wang, You Qin and Wenbao Yang

J. Mar. Sci. Eng. 2023, 11(2), 249; https://doi.org/10.3390/jmse11020249 - 19 Jan 2023

Cited by 16 | Viewed by 2048

Abstract

In this study, a series of resonant-column experiments were conducted on marine clays from Bohai Bay and Hangzhou Bay, China. The characteristics of the dynamic shear modulus (G) and damping ratio (D) of these marine clays were examined. It [...] Read more.

In this study, a series of resonant-column experiments were conducted on marine clays from Bohai Bay and Hangzhou Bay, China. The characteristics of the dynamic shear modulus (G) and damping ratio (D) of these marine clays were examined. It was found that G and D not only vary with shear strain (γ), but they also have a strong connection with soil depth (H) (reflected by the mean effective confining pressure (σ_m) in the laboratory test conditions). With increasing H (σ_m) and fixed γ, the value of G gradually increases; conversely, the value of D gradually decreases, and this is accompanied by the weakening of the decay or growth rate. An intelligent model based on a back-propagation neural network (BPNN) was developed for the calculation of these parameters. Compared with existing function models, the proposed intelligent model avoids the forward propagation of data errors and the need for human intervention regarding the fitting parameters. The model can accurately predict the G and D characteristics of marine clays at different H (σ_m) and the corresponding γ. The prediction accuracy is universal and does not strictly depend on the number of neurons in the hidden layer of the neural network. Full article

(This article belongs to the Special Issue Advance in Marine Geotechnical Engineering)

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29 pages, 10093 KiB

Open AccessEditor’s ChoiceArticle

Field Measurement and Numerical Study on the Effects of Under-Excavation and Over-Excavation on Ultra-Deep Foundation Pit in Coastal Area

by Jifei Cui, Zhenkun Yang and Rafig Azzam

J. Mar. Sci. Eng. 2023, 11(1), 219; https://doi.org/10.3390/jmse11010219 - 14 Jan 2023

Cited by 19 | Viewed by 2773

Abstract

An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through [...] Read more.

An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through the measured data and 3D numerical simulation. The results show that the exceptional performance of the current project is due to the combination of under-excavation and over-excavation during construction. The under-excavation procedure restrained the wall deflections at the middle part of the diaphragm wall, making the corner effects at the corresponding side inapparent. Both the under-excavation and over-excavation procedure can only influence the performance of the excavation in close proximity, while having negligible impacts on the normally excavated areas. Based on the results of this study, practical suggestions are given to improve the performance of similar excavations in the future. Full article

(This article belongs to the Special Issue Advances in Offshore Geotechnics)

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19 pages, 1898 KiB

Open AccessEditor’s ChoiceArticle

Optimization of Maintenance Schedule for Containerships Sailing in the Adriatic Sea

by Nastia Degiuli, Andrea Farkas, Ivana Martić and Carlo Giorgio Grlj

J. Mar. Sci. Eng. 2023, 11(1), 201; https://doi.org/10.3390/jmse11010201 - 12 Jan 2023

Cited by 10 | Viewed by 1486

Abstract

Biofouling attaches to immersed surfaces in between hull cleanings. Due to high speeds and relatively short port times, biofilm often attaches to the immersed surfaces of containerships. In most cases, this type of fouling is not given much importance since it is assumed [...] Read more.

Biofouling attaches to immersed surfaces in between hull cleanings. Due to high speeds and relatively short port times, biofilm often attaches to the immersed surfaces of containerships. In most cases, this type of fouling is not given much importance since it is assumed that it will not cause any fouling penalties. In this paper, the fouling penalties related to fouling with biofilm on the example of the Post Panamax and Post Panamax Plus containership fleets sailing in the Adriatic Sea are assessed. In addition, the investigation is performed for real environmental conditions that a containership can encounter on a sailing route passing through the Adriatic Sea. Thus, the impact of waves and wind is taken into account based on mean values of significant wave height and wind speed for containerships sailing at the design speed along the analyzed route. The procedure for the determination of the detrimental effects of biofilm on the increase in fuel consumption and carbon dioxide emissions is given. Further, the proposed procedure includes the determination of calm water resistance by the Holtrop and Mennen method, the added resistance in waves by Liu and Papanikolaou’s method, spectral analysis using the Tabain’s spectrum for the Adriatic Sea, the wind resistance by the Blendermann method, and added resistance due to biofouling using the Granville method. Thereafter, a time-dependent biofouling growth model proposed by Uzun et al. is incorporated, and the adequate timing for underwater hull cleaning is determined for several hull cleaning costs. The obtained results demonstrate that, from an environmental point of view, proactive hull cleaning should be applied, while, from an economic perspective, optimal timing for underwater hull cleaning is recommended. Full article

(This article belongs to the Section Ocean Engineering)

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15 pages, 764 KiB

Open AccessEditor’s ChoiceArticle

Deep Learning-Based Ship Speed Prediction for Intelligent Maritime Traffic Management

by Sara El Mekkaoui, Loubna Benabbou, Stéphane Caron and Abdelaziz Berrado

J. Mar. Sci. Eng. 2023, 11(1), 191; https://doi.org/10.3390/jmse11010191 - 12 Jan 2023

Cited by 19 | Viewed by 4918

Abstract

Improving maritime operations planning and scheduling can play an important role in enhancing the sector’s performance and competitiveness. In this context, accurate ship speed estimation is crucial to ensure efficient maritime traffic management. This study addresses the problem of ship speed prediction from [...] Read more.

Improving maritime operations planning and scheduling can play an important role in enhancing the sector’s performance and competitiveness. In this context, accurate ship speed estimation is crucial to ensure efficient maritime traffic management. This study addresses the problem of ship speed prediction from a Maritime Vessel Services perspective in an area of the Saint Lawrence Seaway. The challenge is to build a real-time predictive model that accommodates different routes and vessel types. This study proposes a data-driven solution based on deep learning sequence methods and historical ship trip data to predict ship speeds at different steps of a voyage. It compares three different sequence models and shows that they outperform the baseline ship speed rates used by the VTS. The findings suggest that deep learning models combined with maritime data can leverage the challenge of estimating ship speed. The proposed solution could provide accurate and real-time estimations of ship speed to improve shipping operational efficiency, navigation safety and security, and ship emissions estimation and monitoring. Full article

(This article belongs to the Section Ocean Engineering)

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16 pages, 3079 KiB

Open AccessEditor’s ChoiceArticle

The Construction and Application of Dual-Objective Optimal Speed Model of Liners in a Changing Climate: Taking Yang Ming Route as an Example

by Jinxing Lu, Xianhua Wu and You Wu

J. Mar. Sci. Eng. 2023, 11(1), 157; https://doi.org/10.3390/jmse11010157 - 9 Jan 2023

Cited by 23 | Viewed by 1699

Abstract

In a changing climate, ship speed optimization plays an important role in energy conservation and emission reduction. In order to establish a dual-objective optimization model of minimizing ship operating costs and reducing carbon emissions, fuel costs, berthing costs, emission costs and fixed cost [...] Read more.

In a changing climate, ship speed optimization plays an important role in energy conservation and emission reduction. In order to establish a dual-objective optimization model of minimizing ship operating costs and reducing carbon emissions, fuel costs, berthing costs, emission costs and fixed cost during sailing cycles, the emission reduction strategies of ships using MGO in emission control areas and the AMP in ports are taken into account. The PSO algorithm is adopted to find the Pareto solution set, and the TOPSIS algorithm is used to screen the optimal compromise solution, while Yang Ming, a trans-Pacific route, is selected to verify the applicability of the model. The result shows that the optimization model can effectively reduce the operating cost during sailing cycles and control carbon emissions, which can provide references for ship operation decision-making to achieve carbon peaking and carbon neutrality. Full article

(This article belongs to the Special Issue State-of-the-Art in Maritime Safety and Smart Shipping)

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32 pages, 5289 KiB

Open AccessEditor’s ChoiceReview

Recent Advances, Future Trends, Applications and Challenges of Internet of Underwater Things (IoUT): A Comprehensive Review

by Syed Agha Hassnain Mohsan, Yanlong Li, Muhammad Sadiq, Junwei Liang and Muhammad Asghar Khan

J. Mar. Sci. Eng. 2023, 11(1), 124; https://doi.org/10.3390/jmse11010124 - 6 Jan 2023

Cited by 36 | Viewed by 8715

Abstract

Oceans cover more than 70% of the Earth’s surface. For various reasons, almost 95% of these areas remain unexplored. Underwater wireless communication (UWC) has widespread applications, including real-time aquatic data collection, naval surveillance, natural disaster prevention, archaeological expeditions, oil and gas exploration, shipwreck [...] Read more.

Oceans cover more than 70% of the Earth’s surface. For various reasons, almost 95% of these areas remain unexplored. Underwater wireless communication (UWC) has widespread applications, including real-time aquatic data collection, naval surveillance, natural disaster prevention, archaeological expeditions, oil and gas exploration, shipwreck exploration, maritime security, and the monitoring of aquatic species and water contamination. The promising concept of the Internet of Underwater Things (IoUT) is having a great influence in several areas, for example, in small research facilities and average-sized harbors, as well as in huge unexplored areas of ocean. The IoUT has emerged as an innovative technology with the potential to develop a smart ocean. The IoUT framework integrates different underwater communication techniques such as optical, magnetic induction, and acoustic signals. It is capable of revolutionizing industrial projects, scientific research, and business. The key enabler technology for the IoUT is the underwater wireless sensor network (UWSN); however, at present, this is characterized by limitations in reliability, long propagation delays, high energy consumption, a dynamic topology, and limited bandwidth. This study examines the literature to identify potential challenges and risks, as well as mitigating solutions, associated with the IoUT. Our findings reveal that the key contributing elements to the challenges facing the IoUT are underwater communications, energy storage, latency, mobility, a lack of standardization, transmission media, transmission range, and energy constraints. Furthermore, we discuss several IoUT applications while highlighting potential future research directions. Full article

(This article belongs to the Special Issue Underwater Sensing, Signal Processing and Communications)

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25 pages, 8266 KiB

Open AccessEditor’s ChoiceArticle

Survey on Low-Cost Underwater Sensor Networks: From Niche Applications to Everyday Use

by Filippo Campagnaro, Fabian Steinmetz and Bernd-Christian Renner

J. Mar. Sci. Eng. 2023, 11(1), 125; https://doi.org/10.3390/jmse11010125 - 6 Jan 2023

Cited by 20 | Viewed by 5182

Abstract

Traditionally, underwater acoustic modems and positioning systems were developed for military and Oil & Gas industries, that require deep water deployments and extremely reliable systems, focusing on high power expensive systems and leaving the use of low-cost devices only attractive for academic studies. [...] Read more.

Traditionally, underwater acoustic modems and positioning systems were developed for military and Oil & Gas industries, that require deep water deployments and extremely reliable systems, focusing on high power expensive systems and leaving the use of low-cost devices only attractive for academic studies. Conversely, recent developments of low-cost unmanned vehicles, such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), suitable for shallow water coastal missions, and the need of sensors network deployments for measuring water quality and studying the effect of climate change in coastal areas, called to the need of low-cost and low-power acoustic modems and positioning systems that are gaining more and more momentum to date. The use of these devices can enable a wide set of applications, often based on low-cost AUV swarm formations, where an acoustic link between the vehicles is required to coordinate the mission, perform the maneuvers, and maintain the formation along the time. Moreover, they can make environmental wireless sensor deployment cost effective by substituting wired systems. Underwater positioning systems, usually used in large-scale operations, can be finally applied to small-scale application thanks to the reduction in costs, at the price of a lower transmission and positioning range and precision. While in open-sea application this performance reduction is a huge limitation, in river, lagoon, port and lake deployments this is not an issue, given that the extremely shallow water and the presence of many obstacles would deteriorate the acoustic signal anyway, not allowing long range transmissions even with expensive and sophisticated acoustic devices. In this paper, we review the recent developments of low-cost and low-power acoustic communication and positioning systems, both analyzing University prototypes and new commercial devices available in the market, identifying advantages and limitations of these devices, and we describe potential new applications that can be enabled by these systems. Full article

(This article belongs to the Special Issue New Challenges in Autonomous Underwater Networks)

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23 pages, 3687 KiB

Open AccessEditor’s ChoiceArticle

Wind-Assisted Ship Propulsion of a Series 60 Ship Using a Static Kite Sail

by Wayne Formosa, Tonio Sant, Claire De Marco Muscat-Fenech and Massimo Figari

J. Mar. Sci. Eng. 2023, 11(1), 117; https://doi.org/10.3390/jmse11010117 - 5 Jan 2023

Cited by 5 | Viewed by 2592

Abstract

Following the International Maritime Organization’s goal to reduce greenhouse gas emissions, the interest in the application of wind-assisted ship propulsion (WASP) in maritime transportation is on the rise. Although a variety of WASP systems exist, the application in maritime shipping is still limited, [...] Read more.

Following the International Maritime Organization’s goal to reduce greenhouse gas emissions, the interest in the application of wind-assisted ship propulsion (WASP) in maritime transportation is on the rise. Although a variety of WASP systems exist, the application in maritime shipping is still limited, especially in the case of kite sails. This paper presents a numerical model to carry out a theoretical assessment of the influence of the kite planform area and wind speed on the aerodynamic performance of a kite sail providing propulsive assistance to a 75 m long ship having a Series 60 hull. A static kite sail is assumed, on which a tail wind generates a thrust force to pull the vessel via a tether. While the mass of the kite is neglected, that of the tether is accounted for. A model is implemented for the tensioned tether having a catenary profile. The results generally show a positive correlation between the aerodynamic forces and the kite parameters. As expected, the output parameter values corresponding to the optimal angle of attack for a range of vessel speeds are also found to increase with an increasing relative wind speed. It is concluded that a static 320 m² kite sail would be sufficient to meet the entire propulsion requirements of the vessel under consideration under appropriate wind conditions. Full article

(This article belongs to the Topic Advances in Wind Energy Technology)

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15 pages, 8651 KiB

Open AccessEditor’s ChoiceArticle

Long-Term Observations of Sea Surface Temperature Variability in the Gulf of Mannar

by Sandipan Mondal and Ming-An Lee

J. Mar. Sci. Eng. 2023, 11(1), 102; https://doi.org/10.3390/jmse11010102 - 4 Jan 2023

Cited by 6 | Viewed by 1780

Abstract

In this study, we conducted long-term temporal and spatial observations of monthly, interannual, and decadal sea surface temperature (SST) variation in the Gulf of Mannar (GoM) for the period from 1870 to 2018. We obtained climatological data from the Met Office Hadley Centre, [...] Read more.

In this study, we conducted long-term temporal and spatial observations of monthly, interannual, and decadal sea surface temperature (SST) variation in the Gulf of Mannar (GoM) for the period from 1870 to 2018. We obtained climatological data from the Met Office Hadley Centre, UK. The monthly time series revealed that April and August were the warmest and coolest months of the year, respectively. The mean SSTs for April and August were 29.85 ± 0.44 °C and 27.15 ± 0.49 °C, respectively. The mean annual highest and lowest SSTs were observed in 2015 and 1890 with SSTs of 28.93 ± 0.31 °C and 27.45 ± 0.31 °C, respectively, and the annual time series revealed a warming SST trend of 0.004 °C. Decadal time series also revealed a warming SST trend of 0.04 °C, with the highest and lowest mean decadal SSTs being 28.56 ± 0.21 °C in 2010–2018 and 27.78 ± 0.25 °C in 1890–1889, respectively. Throughout the study period, the spatial distribution of climate trends over decades across the GoM revealed a strong spatial gradient, and the region between 6–8° N and 77–78° E was warmer than all other regions of the GoM. Full article

(This article belongs to the Special Issue Sea Surface Temperature: From Observation to Applications II)

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29 pages, 8177 KiB

Open AccessEditor’s ChoiceArticle

The Development and Demonstration of an Enhanced Risk Model for the Evacuation Process of Large Passenger Vessels

by Nikolaos P. Ventikos, Panagiotis Sotiralis, Manolis Annetis, Vasileios C. Podimatas, Evangelos Boulougouris, Fotios Stefanidis, Stefanos Chatzinikolaou and Alessandro Maccari

J. Mar. Sci. Eng. 2023, 11(1), 84; https://doi.org/10.3390/jmse11010084 - 3 Jan 2023

Cited by 11 | Viewed by 2620

Abstract

Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various [...] Read more.

Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various hazards still pose threats to passengers and crew. To deal with this reality, the SafePASS project radically redefines the evacuation process by introducing novel technological solutions. In this context, this paper presents, in detail, an enhanced risk model for the ship evacuation process in order to facilitate the understanding of the actual risks of the process in fire and flooding accidents, and to assess various risk control measures and options toward risk mitigation. The risk model covers the entire event sequence in emergency cases on board, until the survival at sea phase, and it is constructed in two levels, following a combination of event tree analysis and Bayesian networks. Results show the risk corresponds to baseline scenarios for each accident case, which are also verified by relevant IMO and EMSA studies, and an example case of risk control option (RCO) is introduced to the model to demonstrate its ability to assess RCO’s efficiency in terms of risk reduction. Full article

(This article belongs to the Special Issue Risk Assessment and Management in Complex Marine Systems)

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26 pages, 12351 KiB

Open AccessEditor’s ChoiceArticle

Alternative Power Options for Improvement of the Environmental Friendliness of Fishing Trawlers

by Marija Koričan, Maja Perčić, Nikola Vladimir, Neven Alujević and Ailong Fan

J. Mar. Sci. Eng. 2022, 10(12), 1882; https://doi.org/10.3390/jmse10121882 - 3 Dec 2022

Cited by 22 | Viewed by 4306

Abstract

The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency, environmental performance, and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. [...] Read more.

The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency, environmental performance, and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy, i.e., by analyzing ship technical data and assuming its operative profile, or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea, including three phases of the Life-Cycle Assessment (manufacturing, Well-to-Pump (WTP), and Pump-to-Wake (PTW)). Based on the data on fuel consumption, the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy, due to their high price and complex application in an obsolete fleet, they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions, but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers. Full article

(This article belongs to the Special Issue Decarbonization of Ship Power Plants)

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19 pages, 3351 KiB

Open AccessEditor’s ChoiceArticle

The Impact of Marine Engine Component Failures upon an Explosion in the Starting Air Manifold

by Leszek Chybowski, Daniel Wiaterek and Andrzej Jakubowski

J. Mar. Sci. Eng. 2022, 10(12), 1850; https://doi.org/10.3390/jmse10121850 - 1 Dec 2022

Cited by 8 | Viewed by 3968

Abstract

Based on available sources, the frequency of explosions in the marine engine’s starting air manifolds is determined under real conditions. A cause-and-effect analysis of these explosions and their root causes are identified. A probabilistic model of an explosion in the starting air manifold [...] Read more.

Based on available sources, the frequency of explosions in the marine engine’s starting air manifolds is determined under real conditions. A cause-and-effect analysis of these explosions and their root causes are identified. A probabilistic model of an explosion in the starting air manifold of a marine engine is built using a fault tree analysis (FTA). Using a stochastic simulation (Monte Carlo) and an exact reliability availability calculation (ERAC) algorithm applied to the developed FTA model, selected reliability measures are calculated to describe an incident of the top event, which involves an explosion in the starting air manifold. For such an event, several factors are calculated, including the availability, the unavailability, the failure frequency, and the mean time to failure. Based on the simulations, the relative frequency of the top event is determined in relation to the number of events that can simultaneously occur and lead to an explosion. The significance of each basic event is assessed to determine their individual impact on the explosion incident. The following measures are used: the Vesely–Fussell measure of importance, the criticality measure of importance, the Birnbaum measure of reliability importance, and the Birnbaum measure of structural importance. The results of the analysis show that defective starting air valves are most responsible for the explosion incident in the starting air manifold. During the first year of the ship’s operation, the reliability does not fall below the value of 0.65, while the mean time to failure and the top event frequency are statistically at the level of one explosion per approximately 2.28 years of continuous engine operation. Full article

(This article belongs to the Special Issue Risk Analysis of Maritime Accidents)

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39 pages, 14922 KiB

Open AccessEditor’s ChoiceArticle

Technological Potential Analysis and Vacant Technology Forecasting in Properties and Composition of Low-Sulfur Marine Fuel Oil (VLSFO and ULSFO) Bunkered in Key World Ports

by Mikhail A. Ershov, Vsevolod D. Savelenko, Alisa E. Makhmudova, Ekaterina S. Rekhletskaya, Ulyana A. Makhova, Vladimir M. Kapustin, Daria Y. Mukhina and Tamer M. M. Abdellatief

J. Mar. Sci. Eng. 2022, 10(12), 1828; https://doi.org/10.3390/jmse10121828 - 28 Nov 2022

Cited by 21 | Viewed by 3877

Abstract

Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon [...] Read more.

Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon content, vanadium and nickel content, as well as pour point are investigated. Furthermore, the main trends and correlations are also discussed. Based on the graphical and mathematical analysis of the properties, the composition of the fuels is predicted. The key fuel components in Asian ports, the most important of which is Singapore, are hydrodesulfurized atmospheric residues (AR) (50–70%) and catalytic cracker heavy cycle oil (HCO) (15–35%) with the addition of other components, which is explained by the presence of a number of large oil refining centers in the area. In the Middle East ports, the most used VLSFO compositions are based on available resources of low-sulfur components, namely hydrodesulfurized AR, the production facilities of which were recently built in the region. In European ports, due to the relatively low sulfur content in processed oils, straight-run AR is widely used as a component of low-sulfur marine fuels. In addition, fuels in Western European ports contain on average significantly more hydrotreated vacuum gas oil (21%) than in the rest of the world (4–5%). Finally, a mixture of hydrotreated (80–90%) and straight-run fuel oil (10–15%) with a sulfur content of no more than 2.0–2.5% is used as the base low-sulfur component of marine fuels in the ports of Singapore and the Middle East. Full article

(This article belongs to the Special Issue Marine Fuels and Green Energy)

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22 pages, 25599 KiB

Open AccessEditor’s ChoiceArticle

Coastal Vulnerability Assessment for Future Sea Level Rise and a Comparative Study of Two Pocket Beaches in Seasonal Scale, Ios Island, Cyclades, Greece

by Apostolia Komi, Alexandros Petropoulos, Niki Evelpidou, Serafeim Poulos and Vasilios Kapsimalis

J. Mar. Sci. Eng. 2022, 10(11), 1673; https://doi.org/10.3390/jmse10111673 - 6 Nov 2022

Cited by 7 | Viewed by 2157

Abstract

The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between [...] Read more.

The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between the dynamic relationship of coastal environments and marine processes, and the future sea level rise as predicted by scientific reports, is the vulnerability of coastal areas such as sandy beaches, pocket beaches and low-lying coastal areas. The current research aims to assess the coastal vulnerability of Ios Island, Cyclades, Greece for the next 100 years and to identify areas that are comparatively more vulnerable to future sea level changes. Moreover, the seasonal changes concerning sedimentological and morphological characteristics of two pocket beaches of Ios Island, Mylopotas and Magganari, are also examined. From the application of the Coastal Vulnerability Index, 92.37% of the total length of the coastline of Ios Island is characterized by a very low vulnerability as it consists of rocky shores and cliffs, while sandy and pocket beaches are characterized by a very high vulnerability. From the fieldworks and data processing, the seasonal changes mainly concern the seabed’s topography, the sediments’ texture of the collected sand samples, the foreshore and backshore topography, as well as seasonal shoreline displacement, using the Digital Shoreline Analysis System tool (DSAS). Full article

(This article belongs to the Special Issue Coastal Systems: Monitoring, Protection and Adaptation Approaches)

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14 pages, 10589 KiB

Open AccessEditor’s ChoiceArticle

CFD Study on the Influence of Exostructure Elements on the Resistance of a Submarine

by Inno Gatin, Juvel Čokić, Darjan Romić and Joško Parunov

J. Mar. Sci. Eng. 2022, 10(10), 1542; https://doi.org/10.3390/jmse10101542 - 20 Oct 2022

Cited by 7 | Viewed by 2319

Abstract

Submersible vessels designed to operate at low speeds are often designed with an intricate exostructure, as well as other elements that are located outside of the main pressure hull. Exostructure elements are often of cylindrical or rectangular shape, positioned perpendicularly to the flow [...] Read more.

Submersible vessels designed to operate at low speeds are often designed with an intricate exostructure, as well as other elements that are located outside of the main pressure hull. Exostructure elements are often of cylindrical or rectangular shape, positioned perpendicularly to the flow direction. For this reason, their resistance coefficient is relatively large compared to the pressure hull or appendages of a classical submarine. In some cases, the exostructure can significantly increase the wetted surface of the vessel and dominate its resistance. This paper presents a study on how different exostructure elements impact the overall resistance of a submarine relative to the resistance of the cylindrical, smooth, pressure hull. Additionally, the effect of depth is also considered. The study is conducted using the RANS-based CFD method. The subject of the study is a 25 m long tourist submarine designed for depths up to 40 m and a speed of up to 3 knots. Full article

(This article belongs to the Special Issue Design, Analysis and Maintenance of Green Innovative Marine Structures)

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22 pages, 6110 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Operational Modeling of North Aegean Oil Spills Forced by Real-Time Met-Ocean Forecasts

by Panagiota Keramea, Nikolaos Kokkos, Georgios D. Gikas and Georgios Sylaios

J. Mar. Sci. Eng. 2022, 10(3), 411; https://doi.org/10.3390/jmse10030411 - 12 Mar 2022

Cited by 11 | Viewed by 3783

Abstract

Over the latest decades, oil marine pollution has posed a vital threat for global ocean health, since spillages of any scale are related to environmental, social and financial impacts. The worldwide increase in oil and gas demand, and the parallel rise in oil [...] Read more.

Over the latest decades, oil marine pollution has posed a vital threat for global ocean health, since spillages of any scale are related to environmental, social and financial impacts. The worldwide increase in oil and gas demand, and the parallel rise in oil and gas production, exploiting particularly coastal and offshore marine deposits, have significantly increased the risk of accidental oil release to the sea. In the present study, an operational oil spill model was applied to test the oil dispersive properties and to reveal the relative magnitude of weathering processes, after an accidental oil spill release along the main tanker transportation route in the North Aegean Sea. Numerical simulations were implemented using the OpenOil transport and fate numerical model, a subclass of the OpenDrift open-source trajectory framework. This model integrates algorithms with several physical processes, such as oil entrainment, vertical mixing, oil resurfacing and oil emulsification. The oil dispersion model was coupled to real-time met-ocean forecasts received from NOAA-GFS and CMEMS. Present simulation results have focused on the impact of turbulent kinetic energy, induced by the background flow field, on the horizontal spreading of particles, as well as on the evolution of oil mass balance and oil mass properties. Full article

(This article belongs to the Section Marine Pollution)

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19 pages, 5815 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Tailored Leaching Tests as a Tool for Environmental Management of Mine Tailings Disposal at Sea

by Kristine B. Pedersen, Tore Lejon and Anita Evenset

J. Mar. Sci. Eng. 2022, 10(3), 405; https://doi.org/10.3390/jmse10030405 - 10 Mar 2022

Cited by 1 | Viewed by 2723

Abstract

The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea [...] Read more.

The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea disposal. The aim of this study was to contribute to the development of leaching tests, exemplified using mine tailings, planned for submarine disposal in the Repparfjord, Norway. The mine tailings had elevated concentrations of Ba, Cr, Cu, Mn and Ni compared to background concentrations in the Repparfjord. Variables known to affect metal leaching in marine environments (DOC, pH, salinity, temperature, aerated/anoxic) were studied, as was the effect of flocculant (Magnafloc10), planned to be added prior to discharge. Stirred/non-stirred setups simulated the resuspension and disposal phases. Leaching of metals was below 2% in all experiments, with the highest rate observed for Cu and Mn. Multivariate analysis revealed a different variable importance for metals depending on their association with minerals. Higher leaching during resuspension than disposal, and lower leaching with the addition of Magnafloc10, especially for Cu and Mn, was observed. The leaching tests performed in this study are transferable to other materials for sea disposal. Full article

(This article belongs to the Special Issue Sediment Remediation at Harbour)

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24 pages, 3241 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hydrodynamics of a Moored Permeable Vertical Cylindrical Body

by Dimitrios N. Konispoliatis, Ioannis K. Chatjigeorgiou and Spyros A. Mavrakos

J. Mar. Sci. Eng. 2022, 10(3), 403; https://doi.org/10.3390/jmse10030403 - 10 Mar 2022

Cited by 1 | Viewed by 2874

Abstract

In this study, the problems of diffraction and radiation of water waves by a permeable vertical cylindrical body are formulated within the realm of the linear potential theory. The body, which is floating in constant water depth, is moored with a catenary mooring [...] Read more.

In this study, the problems of diffraction and radiation of water waves by a permeable vertical cylindrical body are formulated within the realm of the linear potential theory. The body, which is floating in constant water depth, is moored with a catenary mooring line system. The method of matched eigenfunction expansions for the prediction of the velocity potential in the fluid domain surrounding the body is applied. Furthermore, the static and dynamic characteristics of the mooring system are combined with the hydrodynamics of the body, to set up the coupled motion equations of the dynamical model, i.e., floater and mooring system, in the frequency domain. Numerical results obtained through the developed solution are presented. The results revealed that porosity plays a key role in reducing/controlling the exciting wave loads. As far as the mooring system is concerned, its quasi-static and dynamic characteristics, by employing several motion directions on the fairlead in accordance to varying environmental conditions, are examined, highlighting their effect on the body’s motions. Full article

(This article belongs to the Special Issue Hydrodynamics of Fish Cages and Floating Permeable Structures)

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25 pages, 7253 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparative Assessment and Parametric Optimisation of Large Marine Two-Stroke Engines with Exhaust Gas Recirculation and Alternative Turbocharging Systems

by Daoyi Lu, Gerasimos Theotokatos, Jundong Zhang, Hong Zeng and Keying Cui

J. Mar. Sci. Eng. 2022, 10(3), 351; https://doi.org/10.3390/jmse10030351 - 2 Mar 2022

Cited by 10 | Viewed by 3329

Abstract

Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine’s nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR [...] Read more.

Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine’s nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR and turbocharging system settings of a large marine two-stroke engine with the objective of obtaining the highest engine efficiency whilst ensuring compliance with the prevailing NOx emissions limits. Two typical configurations of the investigated engine (baseline and alternative) are modelled in the GT-SUITE software. Parametric simulations are performed with EGR rates up to 40% along with cylinder bypass rates up to 50%, and the simulation results are analysed to quantify the impact of the engine operation with EGR on the performance and NOx emissions parameters. For the baseline engine configuration, the EGR rate increase considerably deteriorates the brake specific fuel consumption (BSFC), which is attenuated by opening the cylinder bypass valve. The optimal combinations of the EGR and cylinder bypass rates for each operating point are identified for both configurations. Following the comparative assessment between the two engine configurations, recommendations for the engine operating modes are proposed, leading to BSFC improvement in the region of 0.7 to 2.9 g/kWh. This study provides insights for the operational settings optimisation of two-stroke engines equipped with EGR systems, contributing towards the reduction of the associated environmental carbon footprint. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 5938 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Automated Tethered Profiler for Hydrophysical and Bio-Optical Measurements in the Black Sea Carbon Observational Site

by Alexander G. Ostrovskii, Mikhail V. Emelianov, Oleg Y. Kochetov, Vyacheslav V. Kremenetskiy, Dmitry A. Shvoev, Sergey V. Volkov, Andrey G. Zatsepin, Nikolai M. Korovchinsky, Vladimir M. Olshanskiy and Alexander V. Olchev

J. Mar. Sci. Eng. 2022, 10(3), 322; https://doi.org/10.3390/jmse10030322 - 25 Feb 2022

Cited by 8 | Viewed by 3163

Abstract

Biogeochemical cycles of carbon transformation throughout the euphotic zone of the sea are controlled by physical processes, e.g., daily thermocline, variation in solar irradiance, thermohaline convection, and intermittent mixing. These processes should be regularly observed with sufficient time resolution at fixed geographical locations. [...] Read more.

Biogeochemical cycles of carbon transformation throughout the euphotic zone of the sea are controlled by physical processes, e.g., daily thermocline, variation in solar irradiance, thermohaline convection, and intermittent mixing. These processes should be regularly observed with sufficient time resolution at fixed geographical locations. This study provides a brief overview of the carbon observational site in the Northeastern Black Sea. The focus is on the design of a new tethered profiler Winchi for the inner continental shelf part of the site. The profiler hull and two outriggers comprise an open trimaran platform that is positively buoyant and tends to maintain a horizontal position in the water. The lower end of the winch wire is secured to the bottom anchor. By unwinding/winding the wire, the profiler ascends/descends while measuring the depth profiles of marine environment parameters ranging from the seafloor to air–sea interface. After surfacing, the profiler determines its location using the Global Positioning System (GPS) and transmits data to (and from) a server on land through the Global System for Mobile Communications (GSM). Initial field tests with the Winchi profiler at the Northeastern Black Sea shelf exhibited promising results. We report these early tests to demonstrate the use of Winchi. Full article

(This article belongs to the Special Issue Technological Oceanography)

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16 pages, 21388 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigation on a Large-Scale Braceless-TLP Floating Offshore Wind Turbine at Intermediate Water Depth

by Yiming Zhou, Yajun Ren, Wei Shi and Xin Li

J. Mar. Sci. Eng. 2022, 10(2), 302; https://doi.org/10.3390/jmse10020302 - 21 Feb 2022

Cited by 3 | Viewed by 4126

Abstract

Tension leg platform (TLP) is a cost-effective and high-performance support structure for floating offshore wind turbine (FOWT) because of its small responses in heave, pitch, and roll with the constraint of the tendons. China, as the largest market of offshore wind energy, has [...] Read more.

Tension leg platform (TLP) is a cost-effective and high-performance support structure for floating offshore wind turbine (FOWT) because of its small responses in heave, pitch, and roll with the constraint of the tendons. China, as the largest market of offshore wind energy, has shown a demand for developing reliable, viable floating platform support structures, especially aiming at the intermediate water depth. The present paper described a newly proposed 10-MW Braceless-TLP FOWT designed for a moderate water depth of 60 m. The numerical simulations of the FOWT are carried out using the coupled aero-hydro-servo-elastic-mooring calculation tool FAST. The measured wind and wave data of the target site close to the Fujian Province of China were used to evaluate the performance of the FOWT under the 100-, 50-, 5-, and 2-year-return stochastic weather conditions. The natural periods of the platform in surge, sway, heave, pitch, roll, and yaw were found to be within the range recommended by the design standard DNV-RP-0286 Coupled Analysis of Floating Wind Turbines. The largest surge of the water depth ratio among all the load cases was 15%, which was smaller than the admissible ratio of 23%. The tower top displacements remained between −1 m and 1 m, which were at a similar order to those of a 10-MW monopile-supported offshore wind turbine. The six tendons remained tensioned during the simulation, even under the operational and extreme (parked) environmental conditions. The Braceless-TLP FOWT showed an overall satisfying performance in terms of the structural stability and illustrates the feasibility of this type of FOWT at such a moderate water depth. Full article

(This article belongs to the Special Issue Offshore Wind Turbine Foundations)

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14 pages, 2814 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Definition of an Artificial Reef Unit through Hydrodynamic and Structural (CFD and FEM) Models—Application to the Ares-Betanzos Estuary

by María Isabel Lamas Galdo, María Jesús Rodríguez Guerreiro, Javier Lamas Vigo, Ismael Ameneiros Rodriguez, Ricardo Veira Lorenzo, Juan Carlos Carral Couce and Luis Carral Couce

J. Mar. Sci. Eng. 2022, 10(2), 230; https://doi.org/10.3390/jmse10020230 - 9 Feb 2022

Cited by 11 | Viewed by 2987

Abstract

The application of hydrodynamics to the definition of artificial reefs is of great interest since the positioning of the artificial reef modules on the sea floor alters the water velocity field, causing an appropriate circulation of nutrients and promoting a habitat for settling [...] Read more.

The application of hydrodynamics to the definition of artificial reefs is of great interest since the positioning of the artificial reef modules on the sea floor alters the water velocity field, causing an appropriate circulation of nutrients and promoting a habitat for settling desired species. Nevertheless, the designs must be subjected to a structural calculation that will condition the constructive process to be applied. The present research proposes a methodology to determine the geometry of an artificial reef in terms of hydrodynamic and structural criteria. The solution proposed was analyzed through Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM). Using concrete as base material for artificial reefs, four different dosages were proposed with different proportions of cement and water, leading to different mechanical properties, which determine different constructive strategies, such as dwell time in the mold. From the hydrodynamic point of view, it was found that the solution proposed provides a proper replacement of nutrients. From the structural point of view, it was found that the solution proposed does not need steel reinforcements in concrete, which improves the sustainability of the artificial reef. The four different concrete dosages will condition the constructive strategy through the dwelling time in the mold and, for any established production, the necessary number of molds (formworks). Full article

(This article belongs to the Special Issue Numerical Modelling Applied for Marine Environmental Sustainability)

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14 pages, 2047 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Multi-Objective Optimization of a Hydrogen Hub for the Decarbonization of a Port Industrial Area

by Davide Pivetta, Chiara Dall’Armi and Rodolfo Taccani

J. Mar. Sci. Eng. 2022, 10(2), 231; https://doi.org/10.3390/jmse10020231 - 9 Feb 2022

Cited by 16 | Viewed by 5271

Abstract

Green hydrogen is addressed as a promising solution to decarbonize industrial and mobility sectors. In this context, ports could play a key role not only as hydrogen users but also as suppliers for industrial plants with which they have strong commercial ties. The [...] Read more.

Green hydrogen is addressed as a promising solution to decarbonize industrial and mobility sectors. In this context, ports could play a key role not only as hydrogen users but also as suppliers for industrial plants with which they have strong commercial ties. The implementation of hydrogen technologies in ports has started to be addressed as a strategy for renewable energy transition but still requires a detailed evaluation of the involved costs, which cannot be separated from the correct design and operation of the plant. Hence, this study proposes the design and operation optimization of a hydrogen production and storage system in a typical Italian port. Multi-objective optimization is performed to determine the optimal levelized cost of hydrogen in environmental and techno-economic terms. A Polymer Electrolyte Membrane (PEM) electrolyzer powered by a grid-integrated photovoltaic (PV) plant, a compression station and two-pressure level storage systems are chosen to provide hydrogen to a hydrogen refueling station for a 20-car fleet and satisfy the demand of the hydrogen batch annealing in a steel plant. The results report that a 341 kW_P PV plant, 89 kW electrolyzer and 17 kg hydrogen storage could provide hydrogen at 7.80 €/kgH₂, potentially avoiding about 153 tCO_2,eq/year (120 tCO_2,eq/year only for the steel plant). Full article

(This article belongs to the Special Issue Advanced Research in Innovative Ship Energy Systems)

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26 pages, 9658 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Shoaling Wave Shape Estimates from Field Observations and Derived Bedload Sediment Rates

by Tarandeep S. Kalra, Steve E. Suttles, Christopher R. Sherwood, John C. Warner, Alfredo L. Aretxabaleta and Gibson R. Leavitt

J. Mar. Sci. Eng. 2022, 10(2), 223; https://doi.org/10.3390/jmse10020223 - 8 Feb 2022

Cited by 1 | Viewed by 2141

Abstract

The shoaling transformation from generally linear deep-water waves to asymmetric shallow-water waves modifies wave shapes and causes near-bed orbital velocities to become asymmetrical, contributing to net sediment transport. In this work, we used two methods to estimate the asymmetric wave shape from data [...] Read more.

The shoaling transformation from generally linear deep-water waves to asymmetric shallow-water waves modifies wave shapes and causes near-bed orbital velocities to become asymmetrical, contributing to net sediment transport. In this work, we used two methods to estimate the asymmetric wave shape from data at three sites. The first method converted wave measurements made at the surface to idealized near-bottom wave-orbital velocities using a set of empirical equations: the “parameterized” waveforms. The second method involved direct measurements of velocities and pressure made near the seabed: the “direct” waveforms. Estimates from the two methods were well correlated at all three sites (Pearson’s correlation coefficient greater than 0.85). Both methods were used to drive bedload-transport calculations that accounted for asymmetric waves, and the results were compared with a traditional excess-stress formulation and field estimates of bedload transport derived from ripple migration rates based on sonar imagery. The cumulative bedload transport from the parameterized waveform was 25% greater than the direct waveform, mainly because the parameterized waveform did not account for negative skewness. Calculated transport rates were comparable to rates estimated from ripple migration except during the largest event, when calculated rates were as much as 100 times greater, which occurred during high period waves. Full article

(This article belongs to the Section Coastal Engineering)

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31 pages, 3872 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Environmental Impact on Harmful Species Pseudo-nitzschia spp. and Phaeocystis globosa Phenology and Niche

by Stéphane Karasiewicz and Alain Lefebvre

J. Mar. Sci. Eng. 2022, 10(2), 174; https://doi.org/10.3390/jmse10020174 - 27 Jan 2022

Cited by 11 | Viewed by 3516

Abstract

Global environmental change modifies the phytoplankton community, which leads to variations in their phenology and potentially causes a temporal mismatch between primary producers and consumers. In parallel, phytoplankton community change can favor the appearance of harmful species, which makes the understanding of the [...] Read more.

Global environmental change modifies the phytoplankton community, which leads to variations in their phenology and potentially causes a temporal mismatch between primary producers and consumers. In parallel, phytoplankton community change can favor the appearance of harmful species, which makes the understanding of the mechanisms involved in structuring phytoplankton ecological niches paramount for preventing future risk. In this study, we aimed to assess for the first time the relationship between environmental conditions, phenology and niche ecology of harmful species Phaeocystis globosa and the complex Pseudo-nitzschia along the French coast of the eastern English Channel. A new method of bloom detection within a time-series was developed, which allowed the characterization of 363 blooms by 22 phenological variables over 11 stations from 1998 to 2019. The pairwise quantification of asymmetric dependencies between the phenological variables revealed the implication of different mechanisms, common and distinct between the taxa studied. A PERMANOVA helped to reveal the importance of seasonal change in the environmental and community variables. The Outlying Mean and the Within Outlying Mean indexes allowed us to position the harmful taxa niche among the rest of community and quantify how their respective phenology impacted the dynamic of their subniches. We also discussed the possible hypothesis involved and the perspective of predictive models. Full article

(This article belongs to the Special Issue Taxonomy and Ecology of Marine Microorganisms)

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23 pages, 21053 KiB

Open AccessEditor’s ChoiceArticle

Late Quaternary Marine Terraces and Tectonic Uplift Rates of the Broader Neapolis Area (SE Peloponnese, Greece)

by Efthimios Karymbalis, Konstantinos Tsanakas, Ioannis Tsodoulos, Kalliopi Gaki-Papanastassiou, Dimitrios Papanastassiou, Dimitrios-Vasileios Batzakis and Konstantinos Stamoulis

J. Mar. Sci. Eng. 2022, 10(1), 99; https://doi.org/10.3390/jmse10010099 - 12 Jan 2022

Cited by 9 | Viewed by 3784

Abstract

Marine terraces are geomorphic markers largely used to estimate past sea-level positions and surface deformation rates in studies focused on climate and tectonic processes worldwide. This paper aims to investigate the role of tectonic processes in the late Quaternary evolution of the coastal [...] Read more.

Marine terraces are geomorphic markers largely used to estimate past sea-level positions and surface deformation rates in studies focused on climate and tectonic processes worldwide. This paper aims to investigate the role of tectonic processes in the late Quaternary evolution of the coastal landscape of the broader Neapolis area by assessing long-term vertical deformation rates. To document and estimate coastal uplift, marine terraces are used in conjunction with Optically Stimulated Luminescence (OSL) dating and correlation to late Quaternary eustatic sea-level variations. The study area is located in SE Peloponnese in a tectonically active region. Geodynamic processes in the area are related to the active subduction of the African lithosphere beneath the Eurasian plate. A series of 10 well preserved uplifted marine terraces with inner edges ranging in elevation from 8 ± 2 m to 192 ± 2 m above m.s.l. have been documented, indicating a significant coastal uplift of the study area. Marine terraces have been identified and mapped using topographic maps (at a scale of 1:5000), aerial photographs, and a 2 m resolution Digital Elevation Model (DEM), supported by extensive field observations. OSL dating of selected samples from two of the terraces allowed us to correlate them with late Pleistocene Marine Isotope Stage (MIS) sea-level highstands and to estimate the long-term uplift rate. Based on the findings of the above approach, a long-term uplift rate of 0.36 ± 0.11 mm a⁻¹ over the last 401 ± 10 ka has been suggested for the study area. The spatially uniform uplift of the broader Neapolis area is driven by the active subduction of the African lithosphere beneath the Eurasian plate since the study area is situated very close (~90 km) to the active margin of the Hellenic subduction zone. Full article

(This article belongs to the Special Issue Tectonics and Sea-Level Fluctuations)

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21 pages, 7082 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Beachrock Formation Mechanism Using Multiproxy Experimental Data from Natural and Artificial Beachrocks: Insights for a Potential Soft Engineering Method

by Giannis Saitis, Anna Karkani, Eleni Koutsopoulou, Konstantinos Tsanakas, Satoru Kawasaki and Niki Evelpidou

J. Mar. Sci. Eng. 2022, 10(1), 87; https://doi.org/10.3390/jmse10010087 - 10 Jan 2022

Cited by 5 | Viewed by 4149

Abstract

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation [...] Read more.

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat. Full article

(This article belongs to the Special Issue Coastal Systems: Monitoring, Protection and Adaptation Approaches)

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19 pages, 8313 KiB

Open AccessEditor’s ChoiceArticle

The Black Sea Physics Analysis and Forecasting System within the Framework of the Copernicus Marine Service

by Stefania A. Ciliberti, Eric Jansen, Giovanni Coppini, Elisaveta Peneva, Diana Azevedo, Salvatore Causio, Laura Stefanizzi, Sergio Creti’, Rita Lecci, Leonardo Lima, Mehmet Ilicak, Nadia Pinardi and Atanas Palazov

J. Mar. Sci. Eng. 2022, 10(1), 48; https://doi.org/10.3390/jmse10010048 - 2 Jan 2022

Cited by 14 | Viewed by 3747

Abstract

This work describes the design, implementation and validation of the Black Sea physics analysis and forecasting system, developed by the Black Sea Physics production unit within the Black Sea Monitoring and Forecasting Center as part of the Copernicus Marine Environment and Monitoring Service. [...] Read more.

This work describes the design, implementation and validation of the Black Sea physics analysis and forecasting system, developed by the Black Sea Physics production unit within the Black Sea Monitoring and Forecasting Center as part of the Copernicus Marine Environment and Monitoring Service. The system provides analyses and forecasts of the temperature, salinity, sea surface height, mixed layer depth and currents for the whole Black Sea basin, excluding the Azov Sea, and has been operational since 2016. The system is composed of the NEMO (v 3.4) numerical model and an OceanVar scheme, which brings together real time observations (in-situ temperature and salinity profiles, sea level anomaly and sea surface temperature satellite data). An operational quality assessment framework is used to evaluate the accuracy of the products which set the basic standards for the future upgrades, highlighting the strengths and weaknesses of the model and the observing system in the Black Sea. Full article

(This article belongs to the Special Issue Ocean Modelling in Support of Operational Ocean and Coastal Services)

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14 pages, 3419 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Simulation Modeling of a Ship Propulsion System in Waves for Control Purposes

by Maria Acanfora, Marco Altosole, Flavio Balsamo, Luca Micoli and Ugo Campora

J. Mar. Sci. Eng. 2022, 10(1), 36; https://doi.org/10.3390/jmse10010036 - 31 Dec 2021

Cited by 16 | Viewed by 4111

Abstract

The article deals with a simulation approach to the representation of the ship motions in waves, interacting with the propulsion system behavior (diesel engine and propeller). The final goal is the development of a simulator, as complete as possible, that allows the analysis [...] Read more.

The article deals with a simulation approach to the representation of the ship motions in waves, interacting with the propulsion system behavior (diesel engine and propeller). The final goal is the development of a simulator, as complete as possible, that allows the analysis of the main engine thermodynamics in different sea conditions, also in the unfavorable event of dynamic instability of the hull, and the correct management of the other propulsion components. This latter aspect is particularly interesting in some of the last new energy solutions for decarbonization of ships, concerning, for example, auxiliary electric motors, powered by batteries, to support the traditional diesel-mechanical propulsion (especially in heavy weather conditions). From this point of view, a proper analysis of the engine dynamic performance, affected by particular sea states, is fundamental for a smart management and control of shaft generators/auxiliary electric motors, batteries, etc. To this end, the work presents and highlights the main features of a ship simulator, suitable for the study of the new propulsion solutions that are emerging in maritime transport. Some representative results will point out the complex non-linear behavior of the propulsion plant in waves. Moreover, a parametric roll scenario will be investigated, in order to highlight the capability of the conceived simulator in modeling the effects of the dynamic instability of the hull on the propulsion plant. Full article

(This article belongs to the Special Issue Smart Control of Ship Propulsion System)

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18 pages, 6670 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Open Digital Shoreline Analysis System: ODSAS v1.0

by Alejandro Gómez-Pazo, Andres Payo, María Victoria Paz-Delgado and Miguel A. Delgadillo-Calzadilla

J. Mar. Sci. Eng. 2022, 10(1), 26; https://doi.org/10.3390/jmse10010026 - 27 Dec 2021

Cited by 14 | Viewed by 6389

Abstract

In this study, we propose a new baseline and transect method, the open-source digital shoreline analysis system (ODSAS), which is specifically designed to deal with very irregular coastlines. We have compared the ODSAS results with those obtained using the digital shoreline analysis system [...] Read more.

In this study, we propose a new baseline and transect method, the open-source digital shoreline analysis system (ODSAS), which is specifically designed to deal with very irregular coastlines. We have compared the ODSAS results with those obtained using the digital shoreline analysis system (DSAS). Like DSAS, our proposed method uses a single baseline parallel to the shoreline and offers the user different smoothing and spacing options to generate the transects. Our method differs from DSAS in the way that the transects’ starting points and orientation are delineated by combining raster and vector objects. ODSAS uses SAGA GIS and R, which are both free open-source software programs. In this paper, we delineate the ODSAS workflow, apply it to ten study sites along the very irregular Galician coastline (NW Iberian Peninsula), and compare it with the one obtained using DSAS. We show how ODSAS produces similar values of coastline changes in terms of the most common indicators at the aggregated level (i.e., using all transects), but the values differ when compared at the transect-by-transect level. We argue herein that explicitly requesting the user to define a minimum resolution is important to reduce the subjectivity of the transect and baseline method. Full article

(This article belongs to the Special Issue Innovative Representation of the Coastal Topo-Bathymetry and Subsurface for Flooding and Erosion Risk Reduction)

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25 pages, 2660 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

All-In-One: Microbial Response to Natural and Anthropogenic Forcings in a Coastal Mediterranean Ecosystem, the Syracuse Bay (Ionian Sea, Italy)

by Gabriella Caruso, Maria Grazia Giacobbe, Filippo Azzaro, Franco Decembrini, Marcella Leonardi, Stefano Miserocchi, Xiuyun Cao, Chunlei Song and Yiyong Zhou

J. Mar. Sci. Eng. 2022, 10(1), 19; https://doi.org/10.3390/jmse10010019 - 26 Dec 2021

Cited by 6 | Viewed by 3091

Abstract

Bacterial and phytoplankton communities are known to be in close relationships, but how natural and anthropogenic stressors can affect their dynamics is not fully understood. To study the response of microbial communities to environmental and human-induced perturbations, phytoplankton and bacterial communities were seasonally [...] Read more.

Bacterial and phytoplankton communities are known to be in close relationships, but how natural and anthropogenic stressors can affect their dynamics is not fully understood. To study the response of microbial communities to environmental and human-induced perturbations, phytoplankton and bacterial communities were seasonally monitored in a Mediterranean coastal ecosystem, Syracuse Bay, where multiple conflicts co-exist. Quali-quantitative, seasonal surveys of the phytoplankton communities (diatoms, dinoflagellates and other taxa), the potential microbial enzymatic activity rates (leucine aminopeptidase, beta-glucosidase and alkaline phosphatase) and heterotrophic culturable bacterial abundance, together with the thermohaline structure and trophic status in terms of nutrient concentrations, phytoplankton biomass (as Chlorophyll-a), and total suspended and particulate organic matter, were carried out. The aim was to integrate microbial community dynamics in the context of the environmental characterization and disentangle microbial patterns related to natural changes from those driven by the anthropic impact on this ecosystem. In spite of the complex relationships between the habitat characteristics, microbial community abundance and metabolic potential, in Syracuse Bay, the availability of organic substrates differently originated by the local conditions appeared to drive the distribution and activity of microbial assemblage. A seasonal pattern of microbial abundances was observed, with the highest concentrations of phytoplankton in spring and low values in winter, whereas heterotrophic bacteria were more abundant during the autumn period. The autumn peaks of the rates of enzymatic activities suggested that not only phytoplankton-derived but also allochthonous organic polymers strongly stimulated microbial metabolism. Increased microbial response in terms of abundance and metabolic activities was detected especially at the sites directly affected by organic matter inputs related to agriculture or aquaculture activities. Nitrogen salts such as nitrate, rather than orthophosphate, were primary drivers of phytoplankton growth. This study also provides insights on the different seasonal scenarios of water quality in Syracuse Bay, which could be helpful for management plans of this Mediterranean coastal environment. Full article

(This article belongs to the Special Issue Distribution and Metabolic Activities of Marine Microbes in Response to Natural and Anthropogenic Stressors)

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21 pages, 11298 KiB

Open AccessEditor’s ChoiceArticle

A High-Resolution Numerical Model of the North Aegean Sea Aimed at Climatological Studies

by Ioannis G. Mamoutos, Emmanuel Potiris, Elina Tragou, Vassilis Zervakis and Stamatios Petalas

J. Mar. Sci. Eng. 2021, 9(12), 1463; https://doi.org/10.3390/jmse9121463 - 20 Dec 2021

Cited by 4 | Viewed by 3487

Abstract

A new, high-resolution model for the northern part of the Aegean Sea, aimed primarily at climatological research (relaxation and data assimilation-free climate simulations), is hereby presented, along with the results of a 28-year-long simulation covering the period from 1986 to 2013. The model [...] Read more.

A new, high-resolution model for the northern part of the Aegean Sea, aimed primarily at climatological research (relaxation and data assimilation-free climate simulations), is hereby presented, along with the results of a 28-year-long simulation covering the period from 1986 to 2013. The model applied is the Regional Ocean Modelling System (ROMS). A significant improvement over previous models of the Aegean introduced in this work is the replacement of parameterizations of the Dardanelles exchange by a fully three-dimensional simulation of the flow in the Strait. The incorporation of part of the Marmara Sea in the model domain enables the interaction with other regional climate simulations, thus allowing climatic variability of the exchange of the Mediterranean and Black Seas. An extensive validation is carried out comparing the model output with all the available observations from several different platforms, i.e., satellite sea surface temperature and height, T/S profiles from R/V ships, and HF radar surface currents velocity. We focus on the model’s ability to reproduce, to some extent, the distinct thermohaline features and circulation patterns that characterize this specific area of the Mediterranean Sea. Our findings, after comparing simulation results with all the available observations, revealed the model’s sufficiency to simulate very adequately the complex hydrology of the North Aegean Sea, and the model’s ability to reproduce incidents of deep-water formation that took place in the region in previous decades during the Eastern Mediterranean Transient (EMT). Full article

(This article belongs to the Special Issue Hydrodynamic Circulation Modelling in the Marine Environment)

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21 pages, 24372 KiB

Open AccessEditor’s ChoiceArticle

A Projection Method for the Estimation of Error Covariance Matrices for Variational Data Assimilation in Ocean Modelling

by Jose M. Gonzalez-Ondina, Lewis Sampson and Georgy I. Shapiro

J. Mar. Sci. Eng. 2021, 9(12), 1461; https://doi.org/10.3390/jmse9121461 - 20 Dec 2021

Cited by 1 | Viewed by 3374

Abstract

Data assimilation methods are an invaluable tool for operational ocean models. These methods are often based on a variational approach and require the knowledge of the spatial covariances of the background errors (differences between the numerical model and the true values) and the [...] Read more.

Data assimilation methods are an invaluable tool for operational ocean models. These methods are often based on a variational approach and require the knowledge of the spatial covariances of the background errors (differences between the numerical model and the true values) and the observation errors (differences between true and measured values). Since the true values are never known in practice, the error covariance matrices containing values of the covariance functions at different locations, are estimated approximately. Several methods have been devised to compute these matrices, one of the most widely used is the one developed by Hollingsworth and Lönnberg (H-L). This method requires to bin (combine) the data points separated by similar distances, compute covariances in each bin and then to find a best fit covariance function. While being a helpful tool, the H-L method has its limitations. We have developed a new mathematical method for computing the background and observation error covariance functions and therefore the error covariance matrices. The method uses functional analysis which allows to overcome some shortcomings of the H-L method, for example, the assumption of statistical isotropy. It also eliminates the intermediate steps used in the H-L method such as binning the innovations (differences between observations and the model), and the computation of innovation covariances for each bin, before the best-fit curve can be found. We show that the new method works in situations where the standard H-L method experiences difficulties, especially when observations are scarce. It gives a better estimate than the H-L in a synthetic idealised case where the true covariance function is known. We also demonstrate that in many cases the new method allows to use the separable convolution mathematical algorithm to increase the computational speed significantly, up to an order of magnitude. The Projection Method (PROM) also allows computing 2D and 3D covariance functions in addition to the standard 1D case. Full article

(This article belongs to the Special Issue Technological Oceanography)

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12 pages, 2177 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Comprehensive Approach to Account for Weather Uncertainties in Ship Route Optimization

by Roberto Vettor, Giovanni Bergamini and C. Guedes Soares

J. Mar. Sci. Eng. 2021, 9(12), 1434; https://doi.org/10.3390/jmse9121434 - 15 Dec 2021

Cited by 10 | Viewed by 3048

Abstract

This work aims at defining in a probabilistic manner objectives and constraints typically considered in route optimization systems. Information about weather-related uncertainties is introduced by adopting ensemble forecast results. Classical reliability methods commonly used in structural analysis are adopted, allowing to achieve a [...] Read more.

This work aims at defining in a probabilistic manner objectives and constraints typically considered in route optimization systems. Information about weather-related uncertainties is introduced by adopting ensemble forecast results. Classical reliability methods commonly used in structural analysis are adopted, allowing to achieve a simple yet effective evaluation of the probability of failure and the variability associated with the predicted fuel consumption and time of arrival. A quantitative example of application is provided, taking into consideration one of the main North Atlantic routes. Full article

(This article belongs to the Special Issue Ship Routing)

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17 pages, 34038 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Coastal Floods Induced by Mean Sea Level Rise—Ecological and Socioeconomic Impacts on a Mesotidal Lagoon

by Francisco Silveira, Carina Lurdes Lopes, João Pedro Pinheiro, Humberto Pereira and João Miguel Dias

J. Mar. Sci. Eng. 2021, 9(12), 1430; https://doi.org/10.3390/jmse9121430 - 14 Dec 2021

Cited by 9 | Viewed by 3189

Abstract

Coastal floods are currently a strong threat to socioeconomic activities established on the margins of lagoons and estuaries, as well as to their ecological equilibrium, a situation that is expected to become even more worrying in the future in a climate change context. [...] Read more.

Coastal floods are currently a strong threat to socioeconomic activities established on the margins of lagoons and estuaries, as well as to their ecological equilibrium, a situation that is expected to become even more worrying in the future in a climate change context. The Ria de Aveiro lagoon, located on the northwest coast of Portugal, is not an exception to these threats, especially considering the low topography of its margins which has led to several flood events in the past. The growing concerns with these regions stem from the mean sea level (MSL) rise induced by climate changes as well as the amplification of the impacts of storm surge events, which are predicted to increase in the future due to higher mean sea levels. Therefore, this study aims to evaluate the influence of MSL rise on the inundation of Ria de Aveiro habitats and to assess the changes in inundation patterns resulting from frequent storm surges (2-year return period) from the present to the future, assessing their ecological and socioeconomic impacts. For this, a numerical model (Delft3D), previously calibrated and validated, was used to simulate the lagoon hydrodynamics under different scenarios combining MSL rise and frequent storm surge events. The numerical results demonstrated that MSL rise can change the vertical zonation and threaten the local habitats. Many areas of the lagoon may change from supratidal/intertidal to intertidal/subtidal, with relevant consequences for local species. The increase in MSL expected for the end of the century could make the lagoon more vulnerable to the effect of frequent storm surges, harming mostly agricultural areas, causing great losses for this sector and for many communities who depend on it. These extreme events can also affect artificialized areas and, in some cases, endanger lives. Full article

(This article belongs to the Section Physical Oceanography)

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32 pages, 33143 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Long-Term Evolution and Monitoring at High Temporal Resolution of a Rapidly Retreating Cliff in a Cold Temperate Climate Affected by Cryogenic Processes, North Shore of the St. Lawrence Gulf, Quebec (Canada)

by Pascal Bernatchez, Geneviève Boucher-Brossard, Maude Corriveau, Charles Caulet and Robert L. Barnett

J. Mar. Sci. Eng. 2021, 9(12), 1418; https://doi.org/10.3390/jmse9121418 - 12 Dec 2021

Cited by 2 | Viewed by 3100

Abstract

This article focuses on the quantification of retreat rates, geomorphological processes, and hydroclimatic and environmental drivers responsible for the erosion of an unconsolidated fine-sediment cliff along the north shore of the Gulf of St. Lawrence (Quebec, Canada). Annual monitoring using field markers over [...] Read more.

This article focuses on the quantification of retreat rates, geomorphological processes, and hydroclimatic and environmental drivers responsible for the erosion of an unconsolidated fine-sediment cliff along the north shore of the Gulf of St. Lawrence (Quebec, Canada). Annual monitoring using field markers over a period of twenty years, coupled with photo interpretation and historical archive analysis, indicates an average annual erosion rate of 2.2 m per year between 1948 and 2017. An acceleration in retreat occurred during the last 70 years, leading to a maximum between 1997 and 2017 (3.4 m per year) and 2000–2020 (3.3 m per year). Daily observations based on six monitoring cameras installed along the cliff between 2008 and 2012 allowed the identification of mechanisms and geomorphological processes responsible for cliff retreat. Data analysis reveals seasonal activity peaks during winter and spring, which account for 75% of total erosional events. On an annual basis, cryogenic processes represent 68% of the erosion events observed and subaerial and hydrogeological processes account for 73%. Small-scale processes, such as gelifraction, solifluction, suffosion, debris collapse, and thermoabrasion, as well as mass movement events, such as slides and mudflows, induced rapid cliff retreat. Lithostratigraphy and cliff height exert an important control on erosion rates and retreat modes, which are described by three main drivers (hydrogeologic, cryogenic, and hydrodynamic processes). Critical conditions promoting high erosion rates include the absence of an ice-foot in winter, the absence of snow cover on the cliff face allowing unrestricted solar radiation, the repetition of winter warm spells, snow melting and sediment thawing, and high rainfall conditions (>30 mm or SPI > 2). The relationships between hydroclimatic forcing and retreat rates are difficult to establish without taking into account the quantification of the geomorphological processes involved. The absence of quantitative data on the relative contribution of geomorphological processes can constitute a major obstacle in modeling the retreat of cliffs with regard to climate change. Full article

(This article belongs to the Special Issue Coastal Hazards Assessment in Cold Regions)

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