Coastal Engineering Research Articles

Machine Learning in Coastal Engineering: Applications, Challenges, and Perspectives

The integration of machine learning (ML) techniques in coastal engineering marks a paradigm shift in how coastal processes are modeled and understood. While traditional empirical and numerical models have been stalwarts in simulating coastal phenomena, the burgeoning complexity and computational demands have paved the way for data-driven approaches to take center stage. This review underscores the increasing preference for ML methods in coastal engineering, particularly in predictive tasks like wave pattern prediction, water level fluctuation, and morphology change. Although the scope of this review is not exhaustive, it aims to spotlight recent advancements and the capacity of ML techniques to harness vast datasets for more efficient and cost-effective simulations of coastal dynamics. However, challenges persist, including issues related to data availability and quality, algorithm selection, and model generalization. This entails addressing fundamental questions about data quantity and quality, determining optimal methodologies for specific problems, and refining techniques for model training and validation. The reviewed literature paints a promising picture of a future where ML not only complements but significantly enhances our ability to predict and manage the intricate dynamics of coastal environments.

Satellite wave 2D spectrum partition based on the PI-vit-GAN(physically-informed ViT-GAN) method

The abundant spectral data provided by satellite technology are crucial for interpreting the complex marine environment, and the effective and accurate analysis of these data is particularly important for coastal engineering. In this regard, this study proposes a Physically Informed ViT-GAN (PI-ViT-GAN) automatic partitioning method, based on CFOSAT satellite wave spectrum data. Specifically, the model consists of a generator and discriminator. The generator utilizes a contrastive learning strategy as pretraining and through the self-attention mechanism of the ViT model, it focuses on key parts of the spectrum to extract wave group features and wave element parameters. Partitioning-head joint training realizes the output of wave group partition element indices. Subsequently, the discriminator uses the wave group features and a parametric model for spectrum reconstruction and computes the error with the original observed spectrum to evaluate the partition and reconstruction effects. Additionally, this model incorporates two physically corrected functions, wave system classification loss and merging loss, based on the wave age criterion, thereby guiding the training process, and enhancing model efficiency. The results indicate that the reconstructed theoretical spectrum, obtained through the utilization of this method, aligns well with the original sea wave spectrum, demonstrating a precision superior to the spectral partitioning product of CFOSAT's own SWIM. Combining the robust learning capability of the transformer and the regularization of physical prior knowledge, this model can achieve precise, low-cost automated analysis of satellite wave spectra, providing a new scalable method for big data analysis in marine and coastal engineering.

A review on the interactions between engineering and marine life: key information for engineering professionals

AbstractMarine life both affects and is affected by coastal, marine and offshore engineering. As engineering projects have become larger, more frequent and more complex, hence has the number and type of interactions with marine life. Engineers are looking for more information about these interactions so they can better mitigate against any harmful effects to marine life and enhance any positive impacts. This review aims to fill this purpose, giving professional engineers a broad understanding of the impacts that marine engineering projects can cause to marine life and to suggesting some “best practice” mitigation strategies. The review considers the interactions between engineering projects and marine life from three perspectives with a specific example given in each case. First, potential mitigation measures are discussed in the context of offshore windfarms. Secondly, the issue of engineering noise affecting marine species in different ways. Lastly, the engineering solutions employed in the “Great Barrier Reef (GBR) Restoration Project” is exampled. Environmental Impact Assessments used by managers must reference up-to-date and detailed data from biological surveys so that local species that are vulnerable to the specific engineering activities can be identified. The mitigation activities must include acoustic mitigation, be scalable and affordable. This review highlights the need for engineers to liaise closely with marine scientists and biologists to ensure that solutions are appropriate and do not have unexpected or indirect consequences to marine life.

Simulation of the Evolution of Cross-Shore Beach Profiles using SBEACH Modelling

Coastal erosion significantly threatens sandy beaches worldwide, impacting coastal communities and ecosystems. This research investigates the application of SBEACH (Storm-induced BEAch Change), a numerical beach modelling computer programme, as a tool for coastal engineers to predict beach profile evolution in response to wave and tidal actions. The study used SBEACH simulations to explore the equilibrium beach profiles under varying conditions, including wave height, wave period, sediment grain size, and beach slope. This study also examined the effects of storm tides on equilibrium profiles and proposed protective sand dunes' dimensions to safeguard against storm surges. This research highlights SBEACH's potential as a valuable tool for assessing and planning coastal erosion mitigation strategies. While SBEACH provides insights into cross-shore beach profile dynamics, combining it with GENESIS offers a more comprehensive approach to coastal management. However, it is crucial to consider real-world engineering experience and safety factors when deciding on beach stabilisation and protection measures. Coastal countries can benefit from such modelling approaches to better manage and protect their sandy beaches, which play a crucial role in coastal defence and maintaining ecosystem integrity.

Modeling of some hydrodynamics characteristics of Orashi River in the Southern Region of Nigeria

The dynamic nature of rivers and its effect on the inhabitants and its surroundings is of fundamental concern to Hydro Scientists, Coastal Engineers, and Surveyors. These changes have remained unpredicted and hence the focus of this study. The aim of this study is to develop a geo-model of the dynamics of Orashi River in Ogba/ Egbema/ Ndoni Local Government Area of Rivers State. The objectives are to determine the river dynamics parameters, to develop a functional multiple regression model of Orashi River dynamics and to determine the percentage contributions of each of the independent variables. This study was carried out using classical survey methods such as river current measurement, river cross-sectional area determination, river water discharge rate determination, bathymetric operation, runoff water computation, water gauge reading and conventional ground surveying. A multiple regression analysis was carried out using data obtained in 2013, 2015 and 2017 used as the independent variables while the river level changes is used as the dependent variable. The result of this study show changes in the river current and river discharge. The data analysis show the contribution of the independent variable to the dynamics of Orashi River for 2013 to be 24.83%, 30.63%, 20.24%, 0.33% and 24.97% for river current, runoff peak discharge, rainfall intensity, temperature and humidity respectively. The analysis was also carried out in 2015 & 2017and different results were obtained. A functional model of the dynamics of the changes in Orashi River was developed for 2013, 2015 and 2017 which can be used in monitoring the changes in Orashi River.

Wave attenuation and transformation across a highly turbid muddy tidal flat-salt marsh system

Understanding wave processes within the coastal system is crucial for the appropriate design of coastal prevention engineering and offshore structures. To address the limitations of field observations and traditional methods, an array of pressure sensors and optical instruments were deployed across a shoreward intertidal flat consisting of the fluid muddy seabed, bare flat, and salt marsh in a highly turbid coastal area. We found that the Spartina alterniflora salt marsh has the strongest wave dissipation capacity. Although bare flats have the weakest wave dissipation capacity, they are the most extensive within the intertidal zone, resulting in substantial total wave energy dissipation. A noteworthy positive feedback between fluid mud and wave dissipation is observed. Additionally, the incident waves undergo complex transitions during propagation, which are strongly modulated by tidal influences. In particular, when the wave propagation direction is opposite to the tidal current, there is an amplification of wave energy within the tidal flat. This amplification is attributed to the "jacking effect" of the tidal current, hindering the transformation of the wind waves into the low-energy capillary waves. It is important to note that the high-energy infragravity waves are gradually released and steadily increase as the incident waves propagate shoreward. This implies their potentially significant role in nearshore processes, especially during extreme dynamic events or along extensive coastlines.

Importance of sign conventions on analytical solutions to the wave-induced cyclic response of a poro-elastic seabed

This paper discusses the influence of different sign conventions for strains and stresses, i.e. the solid mechanics sign convention and the soil mechanics sign convention, on the form of governing partial differential equations (the static equilibrium equations and the continuity equation) used to describe the wave-induced cyclic response of a poro-elastic seabed due to propagation of a sinusoidal surface water-wave. Some selected analytical solutions, obtained by different authors and published in specialist literature in the form of complex functions describing the wave-induced pore-fluid pressure, effective normal stress and shear stress oscillations in the seabed, have been analysed and compared with each other mainly with respect to different sign conventions for stains and stresses and also with regard to different orientations of the positive vertical axis of the two-dimensional coordinate system and different directions of surface water-wave propagation. The performed analyses of the analytical solutions has indicated many inaccuracies, or even evident errors and exemplary mistakes of wrong-signed values of basic wave-induced response parameters (the shear stress in particular), thereby disqualifying these solutions and their final equations from practical engineering applications. Most of the mistakes found in the literature must be linked to authors’ lack of understanding and consistency in an uniform application of a certain sign convention for strains and stresses in the soil matrix at both stages of mathematical formulation of the governing problem and correct interpretation of equations of the final analytical solution. The present paper, based mostly on a thorough literature review, ought to draw attention and arouse interest among coastal scientists and engineers in proper identification and use of the existing analytical solutions to the wave-induced cyclic seabed response – solutions which differ very often in the applied sign convention for stresses in the soil matrix.

Analysis of the Design and Implementation of a GIS System Incorporating Intelligent Recognition Models

The rapid economic growth, urbanization, and industrialization have led to a scarcity of land resources incoastal areas, exacerbating the conflict between humans and the environment. In order to promote economic development, attention has turned to the sea, and various coastal engineering projects have been undertaken, sparking a wave of land reclamation. However, while these efforts bring economic and social benefits, they also have implications for ecological relationships. To respond to and plan for changes in the coastline and land cover in a timely manner, this paper proposes and constructs a GIS system that integrates remote sensing image recognition models. The system combines geographic information system development technology with image recognition technology, streamlining the processing and identification of image data. This approach is particularly advantageous for marine management departments in their long-term monitoring and dynamic management of coastal lines, ensuring a more effective and efficient response.

A New Multi-Purposes Flume Experiments Facility: Challenges and Opportunity for Tsunami and Coastal Engineering in Indonesia

A New Multi-Purposes Flume Experiments Facility: Challenges and Opportunity for Tsunami and Coastal Engineering in Indonesia

An Application of 3D Cross-Well Elastic Reverse Time Migration Imaging Based on the Multi-Wave and Multi-Component Technique in Coastal Engineering Exploration

Precise surveys are indispensable in coastal engineering projects. The extensive presence of sand in the coastal area leads to significant attenuation of seismic waves within unsaturated loose sediments. As a result, it becomes challenging for seismic waves to penetrate the weathered zone and reach the desired depth with significant amount of energy. In this study, the application of three-dimensional (3D) cross-well elastic reverse time migration (RTM) imaging based on multi-wave and multi-component techniques in coastal engineering exploration is explored. Accurate decomposition of vector compressional (P) and shear (S) waves is achieved through two wavefield decoupling algorithms without any amplitude and phase distortion. Additionally, compressional wave pressure components are obtained, which facilitates subsequent independent imaging. This study discusses and analyzes the imaging results of four imaging strategies under cross-correlation imaging conditions in RTM imaging. The analysis leads to the conclusion that scalarizing vector wavefields imaging yields superior imaging of P- and S-waves. Furthermore, the imaging results obtained through this approach are of great physical significance. In order to validate the efficacy of this method in 3D geological structure imaging in coastal areas, RTM imaging experiments were performed on two representative models. The results indicate that the proposed 3D elastic wave imaging method effectively generates accurate 3D cross-well imaging of P- and S-waves. This method utilizes the multi-wave and multi-component elastic wave RTM imaging technique to effectively leverage the Earth’s elastic medium without increasing costs. It provides valuable information about the distribution of subsurface rock layers, interfaces, and other structures in coastal engineering projects. Importantly, this can be achieved without resorting to extensive excavation or drilling operations. This method addresses the limitations of current cross-well imaging techniques, thereby providing abundant and accurate geological and geophysical information for the analysis and interpretation of 3D geological structures in coastal engineering projects. It has important theoretical and practical significance in real-world production, as well as for the study of geological structures in coastal engineering.

Global spatial dataset of mangrove genus distribution in seaward and riverine margins

Mangroves are nature-based solutions for coastal protection however their ability to attenuate waves and stabilise and accrete sediment varies with their species-specific architecture and frontal area. Hydrodynamic models are typically used to predict and assess the protection afforded by mangroves, but without species or genus distribution information, the results can be significantly different from reality. Data on the frontal genus of mangroves exposed to waves and tides can provide information that can be used in hydrodynamic models to more accurately forecast the protection benefit provided by mangroves. Globally, frontal species were identified from existing mangrove zonation diagrams to create a global mangrove genus distribution map. This dataset aims to improve the accuracy of hydrodynamic models. Data may be of interest to researchers in coastal engineering, marine science, wetland ecology and blue carbon.

Array analysis on a seawall type of deformable wave energy converters

There has been a significant interest in developing Flexible Wave Energy Converters (FlexWECs) that utilise structural deformations to generate electricity and mitigate destructive wave loads to the devices. In the meantime, FlexWECs are most likely to operate in an array format to enhance space usage and power output, as well as provide convenience for maintenance. In this context, the present paper develops a high-fidelity computational model to investigate the interaction of ocean surface waves with an array of seawall-type FlexWECs, which can meanwhile serve coastal engineering purposes. The fluid field is solved using the Navier-Stokes equations, and structural deformations are predicted using a nonlinear finite-element method. Hydroelastic interactions of up to seven deforming FlexWECs with the surrounding wave fields are demonstrated through systematic simulation cases. Based on the simulation results, analyses are conducted to investigate how the wave farm energy output is influenced by the gap between individual devices and the number of devices deployed. Accordingly, empirical design suggestions are provided. Overall, this work innovatively simulates the hydroelastic interactions between waves and multiple deforming structures, and the provided insights are useful for promoting the development of FlexWECs and their wave farms.

Estimates of longshore sediment transport rates along Macumba and Recreio-Barra da Tijuca sandy beaches (Rio de Janeiro, southeastern Brazil)

Due to the complex nature of coastal dynamics, several models were developed to estimate longshore sediment transport (LST) rates. The Coastal Engineering Research Center (CERC), Kamphuis, and Bayram models are among the most used and were applied to three east–west oriented sandy urban beaches from Rio de Janeiro (southeastern Brazil): Macumba, Recreio, and Barra da Tijuca. The wave record from oceanographic buoys and the WaveWatch III (WW3) model were used to identify fairweather periods and increased storminess between 2016 and 2018. Eastwards, median sediment grain-size grades from coarse to medium sand, and is associated with decreasing beach slopes in the same direction. The magnitude of the estimated LST rates varied significantly between the models (Δ ≈ 1,000 m3/day, p < 0.001), although the time-averaged LST rates obtained from the four models indicate eastward transport. The four models identified areas of convergence and divergence of sediment transport with increasing rates to the east. The modeling results may support effective coastal management initiatives when integrated with topographic profiles, numerical modeling, satellite imagery, and historical information.

Evaluation of combined addition of nitrite and chloride on the corrosion behavior of steel bars in modified magnesium oxysulfate cement paste

Magnesium oxysulfate (MOS) cement, a new breed of eco-friendly and carbon-efficient material, boasts exceptional corrosion resistance, especially in harsh environments such as high salt and high humidity. Understanding how it affects the corrosion of steel bars is crucial for its widespread application in coastal concrete engineering. Nitrite-based inhibitors are known for their rust-preventing qualities in cementitious materials. However, more research is needed to determine if nitrite remains effective in MOS cement mixed with chloride salts. This study focuses on the combined effect of chloride and nitrite salts on the corrosion of steel bars in MOS cement. Methods like corrosion area rate, weight loss rate, natural potential, and electrochemical station are employed to study the corrosion behavior of steel in MOS cement. Microscopic techniques help unravel the influence mechanism of phase composition and microstructure on these materials. Furthermore, the study examines how chloride and nitrite contents affect the concentration of free nitrite and chloride ions in MOS cement paste. The analysis model is also established to compare simple linear adsorption, Langmuir adsorption, and Freundlich adsorption. The results indicate that chloride accelerates steel corrosion, while nitrite slows it down in the environment of mixed chloride and nitrite. In low-chloride environments, nitrite content has minimal impact on steel corrosion, but its effect becomes more pronounced in high-chloride settings. The MOS cement mixed with chloride and nitrite primarily consists of Mg(OH)2, MgCl2, MgCO3, MgO, and the 5Mg(OH)2·MgSO4·7 H2O (517 phase). The phase content of passive film on the surface of steel bar is composed primarily of Fe2O3, FeO, Fe, and FeOOH in descending order. As nitrite content increases, the absorption and concentration of free nitrite ions in the MOS cement paste gradually rise, exhibiting a linear trend. Based on the fitting calculations for three distinct adsorption relationships, notably, due to the limited adsorption capacity of MOS cement for nitrite, there's a considerable difference between the simple linear adsorption relationship and the two nonlinear adsorption models in high nitrite environments. However, in low nitrite concentrations, the difference among these three fitting adsorption relationships is little. This research can provide theoretical basis for enhancing the corrosion resistance and durability of coastal concrete engineering with high chloride exposure.

Flow Characteristics in Partly Vegetated Channels: An Experimental Investigation

In this study, we attempt to experimentally investigate the flow turbulence structure in a partly vegetated channel. To achieve the objective of this study, we conducted extensive measurements of flow velocities within and outside the vegetated area, where the flow is fully developed. The experiments were conducted in a very large channel at the Coastal Engineering Laboratory of the Department of Civil, Environmental, Building Engineering and Chemistry at the Polytechnic University of Bari, Italy. The instantaneous three flow velocity components were accurately measured using a 3D-Acoustic Doppler Velocimeter (ADV)-Vectrino system at high frequency. Flow behaviors through the vegetated area, at the interface, and in the unobstructed area were analyzed via time-averaged velocities, turbulence intensity, correlation properties, spectral analysis, and vortex identification. Experimental results showed the development of three distinct characteristic flow zones: (i) a vegetated area of low streamwise velocity, high turbulence intensities, dominant inward interactions, and more intense power spectrum, (ii) a shear layer zone of increasing streamwise velocity, more enhanced transverse flow motion, exponential decrease in turbulence intensities, and frequent ejection and/or outward interaction events, and (iii) a free-stream zone of higher and almost constant streamwise velocity, lower turbulence intensities, frequent sweep and/or inward interaction events, and less intense streamwise power spectrum. The results brought further insights into the flow behaviors in these characteristic flow zones. The extensive and detailed measured data can provide a basis for improving and calibrating numerical simulations of partly vegetated channels.

Spatiotemporal evolution of coastal wetland resources in northern Rizhao under the influence of human activities

Coastal wetlands are a vital resource for the sustainable development of coastal areas. This paper presents a comprehensive monitoring of coastal wetland resources and their evolution in the northern region of Rizhao using multi-period remote sensing data and field investigations. The results show that as of the 2020s, wetland resources in northern Rizhao include subtidal wetlands, artificial wetlands, and intertidal wetlands, accounting for 38.5%, 34.2%, and 26.7% of the total wetland resources, respectively. Over the past 35 years, the evolution of wetlands has been divided into two stages according to the impact of human activities. Before 2000, the wetland area expanded rapidly due to beach aquaculture development. Subsequently, after 2000, the beach wetland area experienced a decline, whereas the landscape wetland area increased. The reason for the change in the wetland area in the later stage was the artificial change in wetland type and beach erosion. By 2020, coastal erosion gradually became the main factor driving the change in wetlands. Therefore, strategies and measures aimed at promoting natural beach growth should be implemented by regulating coastal engineering activities.

Undrained dynamic behavior of geogrid-reinforced coral sand

In this research, the reactions of geogrid reinforcement on the dynamic performance of medium-dense coral sand with various cyclic stress ratios were investigated using stress-controlled undrained dynamic triaxial tests. The results indicate that the insertion of geogrid decreases the dynamic deformations, and pore pressure build-up rate, and impeded the liquefaction of coral sand. The liquefaction resistance of coral sand increases with the increase in the number of reinforcement layers. The liquefaction resistance of coral sand reinforced with three-layer and two-layer geogrid increases by 333% and 6% compared to unreinforced ones. The geogrid reinforcement layers can effectively resist the complete stiffness degradation of coral sand under cyclic loading. The coral sand stiffness decays at an accelerated rate as the cyclic stress ratio increases, whereas increasing the number of reinforcement layers reduces the coral sand stiffness degradation rate, especially for three-layer geogrid reinforced coral sand at low cyclic stress ratios. Generally, the geogrid as a reinforcement material to coral sand is considered a better alternative to enhance the engineering properties of coral sand and offers significant prospects in coastal and marine engineering construction with coral sand.

Short-Term Shoreline Evolution Mapping by using UAV

The boundary separating land from the beachside is known as the coastline. Monitoring and analysing shorelines are crucial because it gives us a better understanding of shoreline changes and identifies beach conditions. Unmanned aerial vehicle (UAV) or drone usage has emerged as a beneficial technology in coastal engineering, notably in the study of shoreline evolutions, because it is more credible and more straightforward to use than the prior technologies. This study aims to gather coastal data, evaluate Pantai Punggur shorelines, and track shoreline changes using processed imagery. The "Pix4D Capture" application has been programmed with the flight planning route, and the drone takes pictures along the entire grid line provided. The data on shoreline evolutions were processed using the Pix4d Mapper and Global Mapper tools. Shoreline changes were tracked continuously from August 4th, 2020, through August 10th, 2021. According to the results, Pantai Punggur is undergoing erosion, as evidenced by the alterations in the shoreline that were apparent in less than a year.

An efficient metamodel to downscale total water level in open beaches

A hybrid methodology is described to obtain the wave set-up and infragravity wave level components for estimating total water level (TWL) in coastal areas, taking into account the surf zone hydrodynamics involved. By combining statistical tools and numerical methods, high-resolution spatial distributions of wave height and water level components are calculated efficiently and seamlessly. The proposed methodology is tested and numerically validated on La Salvé beach (Cantabria, Spain), showing a robust performance for diverse scenarios. The resulting TWL can efficiently evaluate coastal hazards in forecast and hindcast mode, having strong potential as a guideline for coastal engineers, managers and emergency planners in the elaboration of adaptation and mitigation strategies. As an application of the metamodel to these coastal management tasks, significant past storm events have been reconstructed, and their associated TWL-driven coastal flooding hazard has been analyzed using a impact rank scale.

Preface: The 5th International Conference of Water Resources Development and Environmental Protection (ICWRDEP 2023)

The 5th International Conference on Water Resources Development and Environmental Protection 2023 (ICWRDEP 2023) was successfully conducted using a hybrid approach on September 23rd, 2023, at Universitas Brawijaya in Malang, East Java, Indonesia. ICWRDEP has maintained its biennial schedule, an ongoing tradition since the middle of 2015.The Water Resources Engineering Department - Faculty of Engineering - Universitas Brawijaya organized the ICWRDEP 2023 in cooperation with the Ministry of Public Works and Housings of Indonesia, Miyazaki University in Japan, and the Indian Institute of Technology Roorkee, India. The conference topics are River Engineering and Management, Coastal Engineering and Management, Environmental Engineering and Sanitation, Water-Related Disaster Risk Reduction, Water Resources Engineering and Management, and Water-related to Civil, Architectural Engineering. Through the presentation of papers and discussion, the conference provides a platform for researchers, engineers, and academicians to meet and share ideas, achievements, and experiences. This international event is essential in promoting and encouraging practitioners to apply the new concept of water resource development and techniques and enhancing knowledge and understanding with the required specifications of analysis, design, and construction of any engineering concept.We want to convey our deepest gratitude to the Rector of Universitas Brawijaya, the Dean of Engineering Faculty, Keynote Speakers Arie Setiadi Moerwanto, Ph.D from Ministry of Public Works & Housing, Republic of Indonesia, Prof. Keisuke Murakami from Miyazaki University, Japan, Prof. Deepak Khare from Indian Institute of Technology Roorkee, India, Prof. Donny Harisuseno from Universitas Brawijaya, Indonesia, International Advisory Board members, organizing committee, and all participants.The Proceedings of the IOP Conference Series: Earth and Environmental Science feature original research papers stemming from the presentations at ICWRDEP 2023. Experts in relevant fields reviewed all manuscripts submitted to the Proceedings ICWRDEP 2023. We appreciate all of the reviewer’s time and thoughtful comments. Their reviews, we believe, aided in improving the scientific quality of the papers presented.We are looking forward to the 6th ICWRDEP in 2025. We expect more experts and scholars worldwide to attend this international conference.Malang, September 23rd, 2023Universitas BrawijayaIndonesiaList of Committees, Documentation are available in the pdf.