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Wave propagation, a phenomenon involving the transfer of energy over time, is a significant area of study, particularly with respect to sea waves. Due to their unique geometrical properties and inhomogeneous minimum amplitude, sea waves pose distinct challenges for numerical solutions. This research focuses on the analysis of wave stability against various water velocities and breakwater distances from the coastline. The study employs a hybrid approach, utilizing the Finite Element Method (FEM) to determine the movement of fluid elements through a porous, submerged breakwater. The concept of permeability in breakwaters is integral to this analysis. Permeable breakwaters permit a certain proportion of seawater or wave water to pass through, while absorbing or reflecting the remaining component of the waves. Understanding the permeability of breakwaters can enhance the design effectiveness and efficiency, whilst providing insight into potential impacts on coastal ecosystems. The results of the study demonstrate that the distance of the breakwater from the incoming wave influences both the amplitude and speed of the wave. Specifically, a greater distance between the wave and the breakwater results in a decrease in wave height, thereby increasing the stability of the simulation. For example, the directional and speed components of the movement at [x, y, t] for the first amplitude [20, 2, 15] was found to be 0.12515m, the second amplitude [15, 2, 15] 0.13161m, and the third amplitude [10, 2, 15] 0.13097m. This demonstrates that the breakwater's distance significantly influences wave stability, an important factor to consider in future breakwater design and implementation. [ABSTRACT FROM AUTHOR]

Growth and expansion in construction has increased recently and especially in coastal areas. In Alexandria, Egypt, mega projects such as El-Max Port Project (Middle Port), Port of ABU QIR (EG AKI), hotels, and restaurants were spread along the coastal lines, thus, it will need a high electrical energy. Although, the great economic benefits of such projects, it will have some negative impacts, such as overloading on the present grid. According to recommendations of COP 27, Egypt is one of the countries targeting to increase the dependency on green energy to minimize the production of greenhouse gases. This study is interested in wave energy as a renewable source of energy. Using a machine learning model that predicts wave height and wave period through the year 2030 in three separate places (Alamein, Alexandria, and Mersa-Matruh), this study will try to estimate the future amount of wave energy along Egypt's coast. Hourly measurements of the significant height and the mean wave period for the period 1979–2023 have been utilized for this. An extractor for wave energy can also be built on the Overtopping Breakwater for Energy Conversion (OBREC) in order to use this energy to fill the hole in the electric grid. The machine learning model was developed using hourly wave height and period data from three buoys, and as a result, the results have a root mean square error (RMSE) of 0.52. The amount of energy taken, wave power, and system efficiency at each place were then fully determined using a mathematical model for each of the three locations. The area along the coast of Alamein had the highest energy extraction rates, followed by Alexandria and Mersa-Matruh in that order. The results of the mathematical model indicate that the yearly power generation for Alamein, Alexandria, and Mersa-Matruh is 25287 MWhr, 14713 MWhr, and 4865 MWhr, respectively.

Groins are one of the most important facilities used to protect coastal regions. In this research, groins made from a concrete cube were tested experimentally. This research investigates the impact of groin length (Lg) of 105, 135, and 165 cm and groin angle with the normal axis of the shoreline (θ) of 0°, 10°, 20°, and 30° under different dimensionless wave numbers (khg), from 0.34 to 1.26, with the beach slope of 8:1. The units used to indicate erosion and deposition are dimensionless erosion depth (Smax/h), dimensionless deposition height (Dmax/h), and dimensionless erosion hole length (lsmax/h). The sandy bed changes and wave reflection from the groin were monitored. The results showed that the angle of 30° had more impact on beach stability than that of 0°, and more sediments were eroded by short groins than by long ones. The reflection of waves from groins was also studied as a function of the reflection coefficient (kr). As concluded, short groins reflect higher waves than long ones.

Wave energy conversion holds promise for renewable energy, but challenges like high initial costs hinder commercialization. Integrating wave-energy converters (WECs) into shore-protection structures creates dual-function structures for both electricity generation and coastal protection. Oscillating water columns (OWCs) have been well studied in the past with their simple generation mechanism and their out-of-water power take-off (PTO) system, which can minimize bio-fouling effects and maintenance costs compared to other submerged WECs. In addition, a slotted barrier allows for better circulation behind the breakwater while dissipating incoming wave energy through viscous damping. This study examines the performance of a new design which combines an OWC with a slotted breakwater. Small-scale (1:49) laboratory tests were performed with a piston-type wave generator. The performance is evaluated in terms of wave transmission, wave energy extraction, and wave loading under various wave conditions while focusing on the effects of the porosity of the slotted barrier and tide level changes. Results show that under larger waves, a decreasing wave transmission, increasing power extraction from the OWC, and energy dissipation from the slotted barrier are observed. On the other hand, under increasing wavelengths, wave transmission is observed to be constant; this is important for harbor design, which means that the breakwater is effective under a wider range of wavelengths. Porosity allows for more transmission while inducing less horizontal force on the structure.

Wrack lines are a key formation along shorelines that provide organic matter and bring ecological diversity to the local environment. Although wrack line formation has been extensively studied along marine beaches and estuaries, in contrast, knowledge about the environmental variables that promote wrack line formation within inland lakes is widely lacking. In one of the first studies to focus on wrack line formation on lakesides, we analysed the dimensions, volume, elevation and particulate composition of 36 wrack lines across 20 shore sections of a large, oligotrophic Alpine lake with natural water level fluctuations (Lake Constance-Obersee). Using multivariate partial least squares (PLS) regression, we identified the key environmental variables that drive wrack accumulation in lakeside areas. Our results demonstrate that wrack line volume increased with (1) the width of the eulittoral zone as an indicator of the swash conditions (up-rush vs. down-wash), (2) high exposure to wind waves as indicated by the total effective fetch, (3) high exposure to ship waves (catamaran ferry), and (4) the width of the sublittoral zone as an indicator of the availability of source material (Chara spp.) and of the wave energy dissipation rate of the incoming deep water waves. Sediment texture played only a minor role. Wide eulittoral zones and high ship wave exposure favoured high proportions of lake-borne components (Chara remains, mollusc shells), while the reverse was true for land-based components. Anthropogenic wastes were only present in small proportions. We discuss four main factor groups influencing the amount of wrack in marine beaches and on lakeshores considering similarities (waves, breakers, swash, dissipation, relief) and differences (tides vs. annual water level fluctuations) of the two systems, and point out research gaps. We demonstrate that wrack line formation is also important in large inland lakes and can be analysed using basic ideas from relevant marine studies. [ABSTRACT FROM AUTHOR]

Intertidal mudflats are an important component of the coastal geomorphological system at the interface between ocean and land. Accurate and up-to-date mapping of intertidal topography at high spatial resolution, and tracking of its changes over time, are essential for coastal habitat protection, sustainable management and vulnerability analysis. Compared with ground-based or airborne terrain mapping, the satellite-based waterline method is more cost-effective for constructing large-scale intertidal topography. However, the accuracy of the waterline method is affected by the extraction of waterlines and the calibration of waterline height. The blurred boundary between turbid water and mudflats in the tide-dominated estuary brings enormous challenges in accurate waterline extraction, and the errors in estuarine water level simulations prevent the direct calibration of waterline heights. To address these issues, this paper developed a novel deep learning method using a parallel self-attention mechanism and boundary-focused hybrid loss to extract turbid estuarine waterlines accurately from dense Sentinel-2 time series. UAV photogrammetric surveys were employed to calibrate waterline heights rather than the simulated water levels, such that the error propagation is constrained effectively. Annual intertidal topographic maps of the Yangtze estuary in China were generated from 2020 to 2022 using the optimized waterline method. Experimental results demonstrate that the proposed deep learning method could achieve excellent performance in land and water segmentation in time-varying tidal environments, with better generalization capability compared with benchmark U-Net, U-Net++ and U-Net+++ models. The comparison between the generated topography and UAV photogrammetric observations resulted in an RMSE of 13 cm, indicating the effectiveness of the optimized waterline method in monitoring morphological changes in estuarine mudflats. The generated topographic maps successfully identified hotspots of mudflat erosion and deposition. Specifically, the mudflats connected to the land predominantly experienced deposition of 10–20 cm over the two-year period, whereas the offshore sandbars exhibited instability and significant erosion of 20–60 cm during the same period. These topographic maps serve as valuable datasets for providing scientific baseline information to support coastal management decisions. [ABSTRACT FROM AUTHOR]

The coastal zone is a fascinating place that comprises the interface between sea and land. This interface, which is both very dynamic and sensitive, has been affected by strong urban and industrial pressures, and an increase in both traffic and recreational uses, leading to the deterioration of natural habitats and the growing instability of residential areas. Added to this disruption is ongoing climate change, which will lead to rising sea levels and increased wave action. Another problem we are increasingly concerned about is ocean pollution, which has been one of the main causes of threats to deep-water coral reef areas. The main sources of pollution include oil spills and offshore oil drilling. The effects of pollution caused by oil spills can not only seriously affect the global environmental balance of our planet but can also, on a different scale, seriously affect the economy of countries whose main resources depend heavily on the sea. Wave energy has the potential to alleviate the world's dependence on depleting fossil energy resources. With regard to coastal protection, the development of ecological solutions to preserve ecosystems and address coastal processes as an alternative to traditional coastal protection structures (seawalls, groins and breakwaters) is becoming increasingly important. These structures, generally referred to as passive measures, are usually built to alter the effects of sea waves, currents and the movement of sand along the coastline, with the aim of protecting beaches, ports and harbors. The concerns outlined are critically addressed throughout this review article. All of them are highly relevant today and, as demonstrated throughout this article, are expected to grow even more and with much more pronounced consequences starting from the middle of the current century. [ABSTRACT FROM AUTHOR]

Driven by strong winds, huge ocean waves can cause devastating destruction to coastal regions during harsh weather events. There is growing evidence showing that extreme waves can occur in both shallow and deep waters. To protect the coast against the destructive power of huge waves, coastal protection facilities, such as seawalls, are often built along the coast. The integrity and stability of these coastal protection facilities are essential to the safety of coastal regions. Since huge waves are often accompanied by strong winds in real ocean environments, to fill the knowledge gap left by previous relevant studies, this study numerically investigates the hydrodynamic loads and overtopping of a coastal seawall model on a sloped beach under the coupled impact of an extreme wave group and wind. The influences of several main factors are considered, such as water depth, wind speed, and significant wave height. The research results reveal that strong wind can greatly increase the average overtopping rate and enhance the hydrodynamic loads exerted by the extreme wave group on the seawall. [ABSTRACT FROM AUTHOR]

The attenuation of ocean surface waves during seasonal ice cover is an important control on the evolution of Arctic coastlines. The spatial and temporal variations in this process have been challenging to resolve with conventional sampling using sparse arrays of moorings or buoys. We demonstrate a novel method for persistent observation of wave‐ice interactions using distributed acoustic sensing (DAS) along existing seafloor fiber optic telecommunications cables. DAS measurements span a 36‐km cross‐shore cable on the Beaufort Shelf from Oliktok Point, Alaska. DAS optical sensing of fiber strain‐rate provides a proxy for seafloor pressure, which we calibrate with wave buoy measurements during the ice‐free season (August 2022). We apply this calibration during the ice formation season (November 2021) to obtain unprecedented resolution of variable wave attenuation rates in new, partial ice cover. The location and strength of wave attenuation serve as proxies for ice coverage and thickness, especially during rapidly evolving events. Plain Language Summary: Coasts globally are susceptible to erosion by ocean waves. In the Arctic, sea ice near the coast can serve as protection for much of the year. It is particularly challenging to measure waves and ice in this environment, which is necessary to understand the degree of buffering and project future changes. Typical ways of observing waves (e.g., buoys and underwater moorings) have lower success in coastal ice. We show a new way to observe waves and ice in these coastal regions using cables at the seabed deployed for internet connection. With the use of an instrument called an interrogator on shore, fibers in these cables can act like a series of hundreds of wave buoys. This allows us to see that waves are reduced at a variable rate throughout the ice. There are significant opportunities to learn more about the coastal Arctic using this novel technology and method. Key Points: Seafloor fiber optic cables can be used to quantify surface waves in seasonally sea ice‐covered oceansHigh spatial‐resolution wave observations may be used to study wave attenuation in ice at much finer resolution than previously possibleThe rapid evolution of the location and strength of attenuation serves as proxy for the evolution of ice itself [ABSTRACT FROM AUTHOR]

Submerged detached breakwaters (SDBWs) have increasingly been used in recent times as an alternative against their emergent counterpart (EDBWs) to mitigate erosion because the former do not spoil the seascape. Both of these structures are (usually) constructed using precast concrete blocks or natural granite rocks, hence becoming permeable structures. In the case of a single EDBW, a parabolic bay shape equation can be readily used to assess the shoreline planform behind the structure, yet no direct method for the SDBW. In this study, the variation in the initial curved equilibrium planform downdrift of a harbor breakwater, before and after the installation of SDBWs, is estimated by the wave transmission coefficient through an SDBW and calculated longshore sediment transport of which the wave diffraction is considered. This is to say that the shore-normal direction varies (rotates) along a curved equilibrium planform. The applicability of this methodology is validated by comparing the observed data (wave and shoreline change) using closed circuit television on Bongpo-Cheonjin Beach in South Korea, with the calculated shoreline changes. This rational approach, though with some limitations, for shoreline change behind permeable SDBWs will benefit the work on coastal management and mitigation of beach erosion. [ABSTRACT FROM AUTHOR]

Zoos increasingly seek to capture visitors' attention through immersive activities such as encounters that feature animal-learning sessions. In this piece of qualitative research, visitors' perceptions of the emotions and welfare states of animals during such encounters at the Palm Beach Zoo and Conservation Society in Florida under conditions of animal–caregiver interactions were explored. This study incorporated a range of qualitative methods including participant observation, focus group-type discussions, and autoethnography. Reflexive thematic analysis was used to code data and generate themes that were shown to be associated with participants' perceptions. This article discusses the primary theme affiliated with visitors' perceptions for this study: animals' relationships with caregivers and conspecifics. This theme was then filtered through a recently published welfare assessment model to gain insight into how visitors assessed the animals' welfare. I also assessed the animals based on the Model as a form of accuracy-checking. The visitors' and my assessments aligned. These views of visitors' perceptions provide an opportunity for zoos to incorporate guest perceptions as an unexplored component of animal welfare assessments. In doing so, zoos stand to benefit from elevated visitor satisfaction, heightened involvement in zoo activities, as well as better animal welfare. [ABSTRACT FROM AUTHOR]

The sedimentary sequence in Lake Salda has been first documented in detail by analyses of high-resolution seismic profiles and sediment cores together with onshore outcrops along the present shoreline of the lake. Such a multi-proxy approach provides a strong record of changing lake levels and depositional conditions in Lake Salda during the mid to late Holocene. The accurate determination of water-level oscillation and climate conditions relies on the confident deduction from 14C-dated onshore outcrops and sediment cores, which provide calibration for the chronostratigraphic units within high-resolution seismic records. The existence of a dry climate period during the transition from the middle to late Holocene caused the lake level to decrease until 1690 cal years BP. This prominent climate deterioration induced coastal progradation in the lake as inferred from the deltaic sequences in the high-resolution seismic record and favored stromatolite formation, given its oligotrophic water condition. The resultant lowstand of lake level during the late Holocene timely coincided with the Roman Climatic Optimum when a prominent erosional truncation surface and channel incision were formed as observed from the seismic profiles. The late Holocene, during 1690–1050 cal years BP, is represented by a transgressive condition due to lake-level increase, giving rise to a retreat of the deltaic deposit further inland. The ongoing deepening of the lake by contributions of both climate and tectonic activity during the last 650 cal years BP produced Gilbert-type fan deltas along the shoreline and a transgressive sedimentary unit with typical onlapping architecture in the seismic reflection profiles. [ABSTRACT FROM AUTHOR]

Based on the assumption of linear potential flow theory, the scattering problem of a composite breakwater placed in front of an impermeable back wall is theoretically investigated. The velocity potential in each subregion is found using the eigenfunction expansion method. The boundary conditions of the porous region are treated using Darcy's law. The semi-analytical solution of a composite breakwater placed in front of an impermeable back wall is then obtained based on the matching conditions of the boundaries of the different regions. The effects of different parameters on the wave loads and wave amplitudes are investigated. In addition, to better understand the performance of the composite breakwater, the scattering problem of the composite breakwater without considering an impermeable back wall is also investigated. The correctness of this theoretical model is verified by comparing the results with previous work. Based on the results of hydrodynamic calculations and analysis of various aspects of a composite breakwater placed in front of an impermeable back wall, the study of the effect of a composite breakwater placed in front of an impermeable back wall allows us to propose a long-term and cost-effective solution for the protection of various marine facilities from wave attacks. [ABSTRACT FROM AUTHOR]

With the enhancement of people's awareness of environmental protection, more and more marine ecological structures have been developed and studied. Floating breakwaters as offshore floating structures are essential to protect coastal and near-shore areas from strong wave action. This paper proposes a plant ecological floating breakwater (PEFB) in which rigid plants suitable for growing in the sea are grown on the top deck of a box-type floating breakwater. The relevant researches are carried out by a combination of model experiments and numerical simulations in a three-dimensional wave flume. The experimental PEFB is divided into three submerged depth cases, D1 = 2H/3, D2 = 3H/3, and D3 = 4H/3 (H is the thickness of the box-type floating breakwater below the PEFB). The results show that PEFB exhibits better wave attenuation performance in case D3. Floating breakwater with rigid plants has better wave attenuation performance than without plants. [ABSTRACT FROM AUTHOR]

Climate change risks to coastal communities may overwhelm current management strategies. The emergence of nature‐based solutions could provide alternative approaches for climate adaptation; however, studies on their public acceptability are limited. This research focuses on the human dimensions of nature‐based coastal adaptation solutions. The research sought to understand the kind of environmental changes participants were experiencing in their coastal communities of Nova Scotia and what management responses they observed being taken, if any. Online focus groups were held with coastal property owners in Nova Scotia to understand how they assess coastal risks and four approaches to nature‐based coastal adaptation: living shorelines, accommodation, retreat, and dyke realignment to make space for wetland restoration. Results revealed ongoing trust in traditional hard‐line approaches, but also interest in knowing more about nature‐based options. There was general support for living shorelines, albeit with scepticism; a concern that accommodation is just a "band‐aid" approach; resistance to retreat, despite general recognition of its future utility; and a lack of understanding of dyke realignment. The successful implementation of nature‐based coastal adaptation approaches will require more evidence of their viability, better options for financing them, and engagement with communities around the best‐fit alternatives for them. Key messages: In focus groups, coastal residents expressed needs for proof of viability and financing to enhance buy‐in to nature‐based solutions.Living shorelines were supported, but with scepticism about their effectiveness, although dyke realignment was often misunderstood.Accommodation was seen as a "band‐aid" and almost as unpopular as coastal retreat. [ABSTRACT FROM AUTHOR]

While a submerged breakwater has become one of the preferred options of shore protection structures because of its lower impact on the coastal landscape and environment, it causes complicated hydrodynamic characteristics and sometimes fails to meet the expected coastal protection functions. Accurate prediction of wave and current around the structure is therefore essential for appropriate design of a submerged breakwater. This study focused on the influence of the permeability of the submerged breakwater and newly conducted laboratory experiments using permeable and impermeable breakwaters. The model, Simulate WAves till SHore (SWASH), was then applied to these laboratory experiments and the difference of measured and computed wave and current field around the structure was investigated. It was found that the model qualitatively well represented the horizontal distribution of wave heights and phase-averaged current velocities although it overestimated the shoreward volume flux over the impermeable breakwater, but not over the permeable breakwater. Comparison of these contrasting results between permeable and impermeable breakwaters revealed that the phase-averaged bottom shear stress was underestimated on the crest of the impermeable breakwater. This feature highlighted the importance of the bottom friction forces accounting for the wave current coexisting field for better predictions of wave-induced current field around the submerged breakwaters. [ABSTRACT FROM AUTHOR]

Seabirds are biological models for habitat selection studies at different spatial scales. In general, seabirds select areas with a higher availability of prey, but human disturbances can modify their spatial and temporal foraging patterns in urban coastal ecosystems. Here we tested the hypothesis that human activities prevent seabirds foraging on beach sectors that are impacted by urbanization and recreational activities. Seabirds were counted while foraging at the interface between the surf zone and foreshore in three sectors with different levels of urbanization in southeastern Brazil. Physical variables, prey abundance, and human stressors, such as the number of people and dogs, were also measured. The brown booby Sula leucogaster foraged mainly in the least impacted sector, despite the lower abundance of prey and harsher physical conditions. The number of individuals of this species was negatively related to the number of people, indicating a human-induced avoidance behaviour. In turn, the kelp gull Larus dominicanus, a synatropic species, was more abundant in the high impact sector. Our results have implications for the management and conservation of sandy beaches, especially regarding the zoning and selection of priority areas for environmental protection and nature-based ecotourism activities. [ABSTRACT FROM AUTHOR]

Groins are one of the most important facilities used to protect coastal regions. In this research, groins made from a concrete cube were tested experimentally. This research investigates the impact of groin length (Lg) of 105, 135, and 165 cm and groin angle with the normal axis of the shoreline (θ) of 0°, 10°, 20°, and 30° under different dimensionless wave numbers (khg), from 0.34 to 1.26, with the beach slope of 8:1. The units used to indicate erosion and deposition are dimensionless erosion depth (Smax/h), dimensionless deposition height (Dmax/h), and dimensionless erosion hole length (lsmax/h). The sandy bed changes and wave reflection from the groin were monitored. The results showed that the angle of 30° had more impact on beach stability than that of 0°, and more sediments were eroded by short groins than by long ones. The reflection of waves from groins was also studied as a function of the reflection coefficient (kr). As concluded, short groins reflect higher waves than long ones. [ABSTRACT FROM AUTHOR]

Among the Baltic Sea littoral states, Germany is anticipated to endure considerable damage as a result of increased coastal flooding due to sea-level rise (SLR). Consequently, there is a growing demand for flood risk assessments, particularly at regional scales, which will improve the understanding of the impacts of SLR and assist adaptation planning. Existing studies on coastal flooding along the German Baltic Sea coast either use state-of-the-art hydrodynamic models but cover only a small fraction of the study region or assess potential flood extents for the entire region but rely on global topographic data sources and apply the simplified bathtub approach. In addition, the validation of produced flood extents is often not provided. Here we apply a fully validated hydrodynamic modelling framework covering the German Baltic Sea coast that includes the height of natural and anthropogenic coastal protection structures in the study region. Using this modelling framework, we extrapolate spatially explicit 200-year return water levels, which align with the design standard of state embankments in the region, and simulate associated coastal flooding. Specifically, we explore (1) how flood extents may change until 2100 if dike heights are not upgraded, by applying two high-end SLR scenarios (1 and 1.5 m); (2) hotspots of coastal flooding; and (3) the use of SAR imagery for validating the simulated flood extents. Our results confirm that the German Baltic coast is exposed to coastal flooding, with flood extent varying between 217 and 1016 km 2 for the 200-year event and a 200-year event with 1.5 m SLR, respectively. Most of the flooding occurs in the federal state of Mecklenburg-Western Pomerania, while extreme water levels are generally higher in Schleswig-Holstein. Our results emphasise the importance of current plans to update coastal protection schemes along the German Baltic Sea coast over the 21st century in order to prevent large-scale damage in the future. [ABSTRACT FROM AUTHOR]

This article explores the anthropological and social scientific literature on sea level rise and coastal erosion, examining questions of time, the human dimensions of seawalls, tensions over relocation and retreat, and the politics of finance. This includes insights from the author's research in Baja California Sur, Mexico, and along the California coast in the United States, where locally based experiences illustrate not only the challenges of rising seas and erosion, but also the importance of addressing these issues, sooner rather than later, through the critical lenses of anthropology. Overall, this article explores how anthropologists and other social scientists have critically examined the issues, processes, and tensions that shape global coastal responses, and points to directions for future research and engagement with sea level rise, eroding coasts, and humanity's future along the edge of the sea. [ABSTRACT FROM AUTHOR]

This article is an editorial discussing advances in sandy beach ecology during the Anthropocene. The authors highlight the need for innovative approaches and long-term data to understand the effects of human stressors on sandy beach ecosystems. The research topic includes studies on the responses of sandy beach communities to urbanization, the burrowing behavior of beach fauna, the nesting habits of sea turtles, and the impact of management actions on beach resilience. The article emphasizes the importance of considering complex systems and compound variables in order to address the challenges faced by sandy shores in the Anthropocene. [Extracted from the article]

Accurate prediction of wave overtopping at sea defences remains central to the protection of lives, livelihoods, and infrastructural assets in coastal zones. In addressing the increased risks of rising sea levels and more frequent storm surges, robust assessment and prediction methods for overtopping prediction are increasingly important. Methods for predicting overtopping have typically relied on empirical relations based on physical modelling and numerical simulation data. In recent years, with advances in computational efficiency, data-driven techniques including advanced Machine Learning (ML) methods have become more readily applicable. However, the methodological appropriateness and performance evaluation of ML techniques for predicting wave overtopping at vertical seawalls has not been extensively studied. This study examines the predictive performance of four ML techniques, namely Random Forest (RF), Gradient Boosted Decision Trees (GBDT), Support Vector Machines—Regression (SVR), and Artificial Neural Network (ANN) for overtopping discharge at vertical seawalls. The ML models are developed using data from the EurOtop (2018) database. Hyperparameter tuning is performed to curtail algorithms to the intrinsic features of the dataset. Feature Transformation and advanced Feature Selection methods are adopted to reduce data redundancy and overfitting. Comprehensive statistical analysis shows superior performance of the RF method, followed in turn by the GBDT, SVR, and ANN models, respectively. In addition to this, Decision Tree (DT) based methods such as GBDT and RF are shown to be more computationally efficient than SVR and ANN, with GBDT performing simulations more rapidly that other methods. This study shows that ML approaches can be adopted as a reliable and computationally effective method for evaluating wave overtopping at vertical seawalls across a wide range of hydrodynamic and structural conditions. [ABSTRACT FROM AUTHOR]

The consequences of a large wind event occurring in the Southern California Bight on 31 January 2016, are analyzed using data from nearshore island and mainland seabed thermographs (10 to 20 m depths), NOAA meteorologic and wave-rider buoys, a CalCOFI cruise and SST and Chl a data products from satellite remote sensing. Discernible upwelling was discovered approximately 7 hr after the northwesterly wind surpassed 10 m/s, and ultimately coastal water shoaled by at least 90 m. The upwelling character varied according to where the measurements were taken. Leeward seabed thermographs and near mainland shore buoys registered an impulse-like temperature decrease, whereas open-ocean and windward sites measured a more gradual change. The approximately one day long event was followed by an increase in Chl a throughout the bight, with the largest increase being adjacent to the mainland. The Chl a signal vanished after about one week and the temperatures returned to pre-event levels after 11 d. Various upwelling and temperature-relaxation mechanisms are discussed, with two separate upwelling mechanisms suggested and the most likely candidate for relaxation being lateral diffusion of warm offshore water into the nearshore upwelled water. [ABSTRACT FROM AUTHOR]

A baffled permeable breakwater on pile foundation is a novel sort of wave protection structure appropriate for harbor development in an offshore deep -water environment. It has a wide range of potential applications since it can fulfill the demands of wave dissipation and reduction of construction cost, and guarantee the exchange of water inside and outside the harbor. It is challenging to effectively represent the interaction between waves and a permeable breakwater by mathematical modeling because the wave propagation via a permeable structure is a powerful nonlinear mechanism for wave interaction. The physical experiments are conducted to examine a permeable breakwater with its baffle panels in varying water depths and under the influence of various wave elements. The law governing the change in effects on wave reduction of permeable breakwater with respect to the major influencing factors is analyzed, and the experimental results are compared with more widely accepted calculation techniques. The findings demonstrate that water depth and incident wave periods have a significant impact on to absorb waves of the permeable breakwater, but wave height change has a negligible impact. It is appropriate for coastal areas with short wave periods and modest tidal ranges. In addition, recommendations for using the transmission coefficient determination method of a permeable breakwater on pile foundation in engineering design are made by comparing the experimental findings with widely used calculation techniques. [ABSTRACT FROM AUTHOR]

The Lithuanian coastal area is divided by the jetties of the Port of Klaipėda and represents two geomorphologically distinct parts. Local companies and institutions contribute to shaping the coastal area through infrastructure development. Awareness of the changes in the coastal zone can play an important role in the planning and economic feasibility of activities in the Klaipėda coastal region. Therefore, developing a notification system that provides long– and short–term monitoring data for the Lithuanian coastal zone is necessary. In order to do so, the authors intend to create a system that should provide a link between long– and short–term observation and monitoring data for stakeholders, such as wind speed and direction, wave direction and significant height, water and air temperature, atmospheric pressure, sediment size, and distribution, height above sea level, shoreline position, beach width, change in beach protection measures, beach wreckage, and marine debris management, in order to provide timely notifications to end users. [ABSTRACT FROM AUTHOR]

Marine phytoplankton biomass dynamics are affected by eutrophication, ocean warming, and ocean acidification. These changing abiotic conditions may impact phytoplankton biomass and its spatiotemporal dynamics. In this study, we used a nutrient–phytoplankton–zooplankton (NPZ) model to quantify the relative importance of the bottom-up and top-down determinants of phytoplankton biomass dynamics in the Belgian part of the North Sea (BPNS). Using four years (2014–2017) of monthly observations of nutrients, solar irradiance, sea surface temperature, chlorophyll-a, and zooplankton biomass at ten locations, we disentangled the monthly, seasonal, and yearly variation in phytoplankton biomass dynamics. To quantify how the relative importance of determinants changed along a near–offshore gradient, the analysis was performed for three spatial regions, i.e., the nearshore region (<10 km to the coastline), the midshore region (10–30 km), and the offshore region (>30 km). We found that, from year 2014 to 2017, the phytoplankton biomass dynamics ranged from 1.4 to 23.1 mg Chla m−3. Phytoplankton biomass dynamics follow a general seasonal cycle, as is the case in other temperate regional seas, with a distinct spring bloom (5.3–23.1 mg Chla m−3) and a modest autumn bloom (2.9–5.4 mg Chla m−3). This classic bimodal bloom pattern was not observed between 2003 and 2010 in the BPNS. The seasonal pattern was most expressed in the nearshore region. The relative contribution of factors determining phytoplankton biomass dynamics varied spatially and temporally. Throughout a calendar year, solar irradiance and zooplankton grazing were the most influential determinants in all regions, i.e., they jointly explained 38–65% of the variation in the offshore region, 45–71% in the midshore region, and 56–77% in the nearshore region. In the near- and midshore regions, nutrients were the greatest limit on phytoplankton production in the month following the spring bloom (44–55%). Nutrients were a determinant throughout the year in the offshore region (27–62%). During winter, sea surface temperature was a determinant in all regions (15–17%). By the high-resolution spatiotemporal analysis of the relative contributions of different determinants, this study contributes to a better mechanistic understanding of the spatiotemporal dynamics of phytoplankton biomass in the southern North Sea. This detailed understanding is anticipated to contribute to the definition of targeted management strategies for the BPNS and to support sustainable development in Belgium's blue economy. [ABSTRACT FROM AUTHOR]

Developing new technologies to utilize natural renewable energy resources and fluxes is critical to mitigate climate change and energy crisis. As a renewable energy resource, wave energy is more predictable and has a higher power density compared to solar and wind. However, the technology for wave energy harvesting is still relatively nascent. One of the major challenges as the sector developers is the lack of spatial–temporal representation of wave resources, or wave power generation, from a generic WEC. This paper proposes a novel Wave Net Power Assessment (WNPA) method by utilizing the theoretical Wave Energy Converter (WEC) power limits (including the radiation power limits, Budal's limit, and gross wave power), and applies it to a decade of wave conditions across the USA East Coast, West Coast and Hawaiian Islands. The WNPA method assesses the wave resource from device point of view (unlike traditional gross wave resource assessment) and is generally applicable to WECs regardless of dimension, size, and degrees of freedom (DoFs). The geospatial application of the WNPA method allowed for the analysis of wave power production potential along U.S. coastlines and provides WEC developers meaningful data to make decisions about the best spatial region to deploy certain WECs. Numerical simulations are conducted for WECs with 5 different sizes, 3 different operating modes across the West Coast, East Coast, and Hawaii over 10 years. In addition, productivity, efficiency and gross power quality comparisons are made in terms of the size and degree-of-freedom for WECs deployed at certain ocean sites (e.g., PacWave). A few of the most important findings: (1) The net wave power is dramatically smaller than the gross wave power, which indicates the new WNPA method has a more conservative assessment of the wave power potential; (2) A heaving 10 m WEC is found to have the highest (compared to other sizes and degrees of freedom) absorption efficiency on the West Coast and Hawaii; (3) For smaller 2 m surging/pitching WECs, ocean sites on the East Coast (e.g., Diamond Shoals, NC) maximize power production. (4) There are distinct trade-offs between maximizing power or minimizing power quality and dependencies exists between the location of interest, the WEC size, and the priority degree of freedom. The proposed methodology can be utilized by WEC technology and project developers to conduct apriori preliminary analysis of WEC deployment locations and device characteristics. • Introduction of novel Wave Net Power Assessment (WNPA) methodology for assessing the wave energy resource by providing an upper practical limit of WEC power generation. • Derivation of generic methodology to predict the performance of a WEC; depending only on WEC characteristic dimension and mode of motion. • Geospatial analysis of WEC generation across the US West Coast, East Coast and Hawaiian Islands with five differing WEC sizes, with three different degrees of motion, over a 10-yr period. • Quantification of the mean power, conversion efficiency and co-efficient of variation over a decade. • Ability to quickly understand the spatial and temporal monthly variability of various WEC archetypes in specific locations within US waters. [ABSTRACT FROM AUTHOR]

Gravel beaches in the Mediterranean ecoregion represent an economically important and unique habitat type. Yet, burgeoning tourism, intensive coastal development and artificial nourishment of beaches may jeopardize their ecological communities. To date, species that reside on gravel beaches and the consequences of beach alterations are poorly understood, which hampers the development of a sustainable coastal tourism industry along the region's shorelines. Using a simple collection method based on dredging buckets through the intertidal section of beaches, we quantified the microhabitat association of two sympatric clingfish species in the genus Gouania at seven natural and an artificial gravel beach based on sediment characteristics. We hypothesized that slender (G. pigra) and stout (G. adriatica) morphotypes would partition interstitial niche space based on sediment size, which may affect the vulnerability of the species to changes in gravel beach composition due to coastal development. We detected substantial differences in gravel composition within and among the sampled beaches which suggests scope for microhabitat partitioning in Gouania. Indeed, we found significant relationships between species identity and the presence/absence and abundance of individuals in hauls based on their positioning on PC1. Our results suggest that modifications of gravel beaches through coastal development, including beach nourishment, intensifying coastal erosion, or artificial beach creation, may have detrimental consequences for the two species if sediment types or sizes are altered. We posit that, given the simplicity and efficacy of our sampling method and the sensitivity of Gouania species to prevailing gravel composition, the genus could serve as an important indicator for gravel beach management in the Mediterranean ecoregion. [ABSTRACT FROM AUTHOR]

Inspired by the concept of superscattering in optics, we for the first time theoretically predict and experimentally demonstrate the superscattering phenomenon in water waves. The subwavelength superscatterer is constructed by multi-layered concentric cylinders with an inhomogeneous depth profile. The superscatterer breaks the long-held single-channel scattering limit by several times and thus significantly enhances the total scattering strength. The underlying mechanism originates from the near degeneracy of the resonances of multiple channels. We fabricate the superscatterer prototype and experimentally measure the near-field patterns, which are consistent with theoretical prediction and numerical simulation. Our study opens a new avenue to strengthen water-wave scattering and deepen the understanding in water waves, which can be useful for ocean energy harvesting and harbor protection. [ABSTRACT FROM AUTHOR]

Wetland ecosystems can be effectively managed to produce sustainable services and benefits for human beings. Thus, it is considered as an essential component of Earth's life-support system. It has been studied quantitatively, but few studies have focused on exact local characteristics of various wetlands in Greater Bay Area (GBA) to continuously quantify the value of ecological services. Against the background of fast urbanization and wetland degradation in GBA, as a famous ecological core in China, Huiyang is of great importance for its ecological, social, and cultural functions in the whole region. Thus, this study aims to provide decision-making references for wetland protection and development in this area. All the wetlands in Huiyang, including mangroves, inland tidal flats, and coastal tidal flats, were included as research objects. Based on the investigated wetland resources, multiple methods were combined to study their wetland services, including pollution prevention cost, substitution cost, and travel expense calculation. Creatively, five factors were selected by Analytic Hierarchy Process (AHP) method: water purification, carbon fixation, shore protection, biodiversity conservation, and leisure tourism. After a comparison, the results showed that the total value of wetland ecosystem services in Huiyang was nearly 30.47 million dollars in 2020. Among the three types of services, the value of leisure tourism service was dominant, accounting for 95%. Among the five factors, the ranking sequence was: leisure tourism, carbon sequestration, biodiversity conservation, shore protection, and water purification. Based on the results, this paper provides a basis for more cities to scientifically measure the value of their wetlands, further utilize the wetland services in a more balanced way. [ABSTRACT FROM AUTHOR]

The effect of artificial island on the geomorphologic processes in the coastal area under the coupled hydrodynamics, wave, and sediment transport system is a complicated and multi-scale problem. Studying these dynamic processes will suggest how coastal ecological restoration should be conducted. In this study, a unified, unstructured, gridded coupled hydrodynamics, wave, and sediment transport model and a topographic evolution model were adopted. Based on the field observations of water depth, velocity, suspended sediment concentration, bed sand, and quaternary thickness, a high-spatiotemporal-resolution numerical simulation of the offshore dynamic environment under the disturbance of artificial island was performed, and the accuracy of the calculation was verified. The research showed that the coupling system with an unstructured mesh was able to reproduce the flow and sediment transport processes with acceptable accuracy. The contracted flow zone between the artificial island and the coastline, the runoff and alongshore current from the river, as well as the tidal flow from the ocean, worked together to mold the local complex morphology around the artificial island. The coupled modeling system, supported with parallel computation, can be used to study coastal environments with small-scale wading structures. [ABSTRACT FROM AUTHOR]

A breakwater is a structure used to dissipate the wave energy in order to protect the shore and maintain tranquility inside the harbor basin. The quarter-circle breakwater (QBW) constitutes a quarter circular front wall facing incident waves, a vertical rear wall, and a horizontal base slab placed on a rubble mound foundation. In this study, a comprehensive experimental investigation is carried out in order to examine the wave overtopping characteristics of an emerged non-perforated and seaside perforated emerged quarter-circle breakwater subjected to regular waves. A model scale of 1:30 is selected based on the limitations of testing facilities. For the current investigation, an emerged QBW models of the radius 0.50 m is utilized. The model is tested for six different perforations ranging between 0% and 20%, with a constant perforation radius of 0.016 m. The paper highlights the influence of wave steepness (Hi/gT2), relative crest freeboard (Rc/Hi), relative water depth (d/gT2) on the wave overtopping performance of the seaside perforated and non-perforated QBW models. An increase in wave steepness is found to increase the dimensionless mean wave overtopping discharge. Also, an exponential decrease in dimensionless mean wave overtopping discharge is observed with an increasing relative freeboard. The relative freeboard is found to be one of the predominant parameters influencing the wave overtopping discharge rate. [ABSTRACT FROM AUTHOR]