Coastal Engineering

This paper critically interrogates the Lagos-Calabar Coastal Highway project as a case study of infrastructure-led development in contemporary Nigeria. The highway, stretching for 700 kilometres, was heralded as a transformation corridor that would enhance tourism, trade, and regional integration. Yet, questions of economic viability, political agenda, and socioenvironmental implications have become the fulcrum for many debates. Synthesising policy documents, media reports, and early stakeholder perceptions, the highway project is linked with discourses on infrastructural modernity, elite statecraft, and uneven development in postcolonial Africa. The paper investigates the financial architecture, cost estimates, and purported economic justifications for the project, while weighing it against the possibilities of coastal economic stimulation or the fiscal liabilities that it may be confronted with. The paper further looks into social and political aspects of the project, especially in relation to timing, procurement opacity, and consequences for communities and ecologies along the alignment. Focus areas include contested sites such as Okun Ajah, Lagos, where matters regarding displacement, compensation, and heritage loss remain unresolved. In conclusion, the paper argues that while the Lagos-Calabar Coastal Highway represents a bold infrastructural vision, it also exemplifies the contradictions of state-led megaprojects in Nigeria-promising connectivity and growth, yet entangled in complex politics, environmental trade-offs, and contested futures.

Environmental contours are an established method in probabilistic engineering design, especially in ocean engineering. The contours help engineers to select the environmental states which are appropriate for structural design calculations. Defining an environmental contour means enclosing a region in the variable space which corresponds to a certain return period. However, there are multiple definitions of environmental contours for a given return period as well as different methods to compute a contour. Here, we analyze the established approaches and present a new concept which we call highest density contour (HDC). We define this environmental contour to enclose the highest density region (HDR) of a given probability density. This region occupies the smallest possible volume in the variable space among all regions with the same included probability, which is advantageous for engineering design. We perform the calculations using a numerical grid to discretize the original variable space into a finite number of grid cells. Each cell's probability is estimated and used for numerical integration. The proposed method can be applied to any number of dimensions, i.e. number of different variables in the joint probability model. To put the highest density contour method in context, we compare it to the established inverse first-order reliability method (IFORM) and show that for common probability distributions the two methods yield similarly shaped contours. In multimodal probability distributions, however, where IFORM leads to contours which are difficult to interpret, the presented method still generates clearly defined contours.

In this paper we explore the potential of Digital Earth Africa (DE Africa) coastlines products for the calculation of one of the Erosion Warning Indicator Namely Long-Term shoreline trend indicator. The parameter is calculated and estimated based on the relationship between the cross-shore annual shoreline positions and the annual observation. DE Africa provide information related on the coastal dynamics for the period of 23 years. Here, we analyse the Digital Earth Africa (DE Africa) coastlines products V0.4.2 by performing the regression modelling to calculate the long-term shoreline trend indicator. The methodological approach proposed allowed to extract the long-term trend of shoreline changes at continental, national and local scales. The results indicated that the Africa's coastline have been both retreating and advancing. Such processes impacted the African population of about 709775 living within 1 km of the shoreline and low-lying flat areas.

There are geomorphological deficiency and mistakes on the definitions and explanation involved in the coast law and the relevant regulations. For this reason, rapidly increase have been shown on numbers of lawsuit concerned with coasts in the law court from day to day. In the legal precedure, the explanations of coast law have been accepted as basic. Consequently, the problematic items of coast law and the reports of consultative authority and determining commission have never got along with each other. In this way, claimant and defendant of the law court have a right to object to the law court. For solution of the problem, the definitions and explanation in the coast law and therelevant regulations have been in need of correction so as to the content of  geomorphological detail which will not give opportunity to wrong interpretations. In solution of the problems dealing this subject, it will be important contribution that this arragements are involved in the coast law. Keywords: Co...

It is known that DARPA SUBOFF submarine model does not have a horizontal stability in deep water. In this study, the horizontal stability of submarine model moving during the periscope (snorkel) position or close to the free water surface, has been determined in 3 DoF (degrees of freedom). While determining the submarine stability and hydrodynamic maneuvering derivatives, linear coefficients of lateral translational force at different depths and linear coefficients of yaw angular moment were used. The depths were selected as 1.1D, 2.2D, 3.3D and 6D, here D is submarine diameter. The maneuvering derivatives were obtained by performing systematic analyzes with the computational fluid dynamics method. Necessary validation studies were also carried out in computational analyzes. In computational fluid dynamics analysis, longitudinal and lateral force derivatives, and yaw moment derivatives were determined and X0, Xv, Xd, Xẟ, Yv, Yr, Yẟ, Nv, Nr ve Nẟ terms were computed in the linear mod...

Norway is particularly susceptible to large rockslides due to its many fjords and steep mountains. One of the most dangerous hazards related to rock slope failures are tsunamis that can lead to large loss of life. Many rockslides are clustered east of the Storfjord and Lyngen fjord in Troms county, northern Norway, where several mapped unstable rock slopes occur within the zone of sporadic permafrost. Among these, the Nordnes rockslide has been classified as high-risk due to the severe consequences should catastrophic failure occur. In order to fully understand the kinematics and geometric configurations susceptible for sliding, it is imperative to obtain precise measurements of the stability of potential unstable rock slopes. I am grateful to a lot of people who made it possible for me to write this thesis. My supervisors at University of Tromsø, Geoffrey D. Corner and Steffen Berg for giving me this thesis, for their patience, guidance and good conversations in the field. My external supervisor, Tom Rune Lauknes from Norut for his continuous encouragement and guidance in the, for me, new field of remote sensing. Further he put me in contact with key persons at Geological Survey of Norway, Nordnorsk fjellovervåkning and Åknes/Tafjord Beredskap. And last but not least for introducing me to the coffee machine at Norut. Yngvar Larsen from Norut for giving me expert advice during InSAR processing and for giving me access to his decomposing scripts that made it possible for me to produce 2D InSAR data. I would like to thank the handymen at Nordnorsk fjellovervåkning for their good humor and hospitality, which resulted in both accommodation and transportation during my field work. Further, I would thank John Dehls at Geological Survey of Norway and Jan P. Holm for University of Tromsø for teaching me tricks in ArcMap. Halvor Sverre Saeter Bunkholt and the rest of the gang from Geological Survey of Norway, for letting me participate on educational and fun days in the mountains during their field campaign in August 2012. Lars Harald Blikra for giving me detailed description, good advice, and insights into the sleeping dragon of the Nordnes rockslide while inspecting drill cores. I would like to thank my Mum, Dad and my Sister for encouraging me and correcting numerous spelling errors. Thanks to the gang at "The Red Barracks" at The Department of Geology. I appreciate the many good conversations we have had during lunches and field excursions over the years. Norut together with The Department of Geology in The Faculty of Science and Technology at the University of Tromsø, supported me with funding that made it possible to conduct my field work and attend the AGU conference in San Francisco. This thesis would not be possible without the good will of certain people sharing their datasets. Åknes/Tafjord Beredskap IKS shared their mapped structures from Nordnes rockslide. The TerraSAR-X data used, have been provided through the German Aerospace Centre (DLR) TerraSAR-X AO projects #GEO0565 and GEO0764. GPS data originate from Nordnorsk fjellovervåkning. The digital elevation model was provided by Norwegian Mapping Authority (NMA) and orthophotos used were provided by vi NorgeDigitalt/NorgeiBilder. In addition my supervisor, Geoffrey D. Corner, let me use his quaternary geological map over Storfjord that is still under preparation. I consider myself lucky to have been part of at rewarding and challenging journey, and have saved the greatest thanks of all to my sweet and caring wife Anita and our wonderful children Sigrid, Gabriel and Sondre. Thanks for your patient and support. vii (Fig. 2). The name 2D InSAR, refer to the fact that all data are vectors in the East-West plane. See Section 2.4 for a more thorough explanation of decomposition of ascending-and descending InSAR displacement data to 2D InSAR displacement data.

The Curtain Wall-Pile Breakwater (CPB) is comprised of a precast concrete wall structure that is upheld by pillars. The effectiveness of this breakwater has been extensively examined through experimental and numerical approaches in comparison to the conventional gravitational breakwater due to its reduced underwater footprint, which could be more environmentally sustainable. A Smoothed Particle Hydrodynamics (SPH) model using the open-source algorithm DualSPHysics is presented in this paper to simulate wave reflection on a CPB for multiple variables. This study focused on assessing the CPB's performance in reflecting wave energy represented by the reflection coefficient (Cr), with a detailed investigation of two key parameters: relative depth, which is the ratio of wall depth to water depth (h/d) and wave steepness (H i /L). The physical model was also tested in a laboratory flume to confirm the accuracy of the simulation results obtained through SPH. A fluid particle size of 0.5 cm was used, resulting in a simulation comprising approximately 9,320,717 particles. The results indicate that the Cr is directly proportional to the h/d and significantly influenced by H i /L. Specifically, changes in h/d from 0.0 to 0.7 resulted in Cr increases from approximately 0.21 to 0.49 for lower wave steepness (H i /L = 0.0097) and from approximately 0.36 to 0.60 for higher wave steepness (H i /L = 0.0499). The quantitative analysis based on the quadratic regression equations shows that both the relative depth and wave steepness significantly influence the effectiveness of the CPB. The reflection coefficient increases with the relative depth, with a more significant effect observed for higher wave steepness. These findings underline the importance of considering both parameters in the design and optimization of breakwater structures to ensure robust and effective coastal protection.

The purpose of this study is to propose a stabilization method for seabed subjected to sea wave loading and verify the efficiency of the method through a FEM analysis. The principle of the stabilization method proposed in the study is the suppression of the seepage force inside the seabed. Since the seepage force is a kind of body force and is fundamentally related to the gradient of potential water head in the seabed, the unification of potential water can be effective for reducing the hydraulic gradient and the associated seepage force. In the method permeable columns which are installed into seabed near structures with a certain interval and depth are utilized for propagating water pressure from the surface to the inside of seabed.

Results To ensure a proper coverage of the whole Venice Lagoon, 8 tide gauge stations have been selected for the aim of the present analysis. Piattaforma Acqua Alta, located 8 nautical miles off the venetian coastlines, has also been considered as reference station, being not influenced by any changes occurred inside the Lagoon (Fig.1). As regards tide amplitudes within the lagoon, they appear to be substantially stable until the years 2003/2004, which is the period when works of the Mo.S.E. project at the three inlets started. Instead, in the following years, all stations registered a notable fall of tide amplitude. The response of the Venice Lagoon appears not to be homogeneous: Northern Lagoon stations show a minor decrease in amplitude in comparison with Central and Southern Lagoon. Observed changes involve not only tidal amplitude but also phase delays with respect to the sea. Changes of this magnitude are very likely to be related with the modifications occurred at the three i...

De superwinsten van de grote farmaceutische
industrieën worden betaald uit de hoge prijzen die
patiënten voor hun medicijnen moeten neertellen.
Maar er is een concreet en betaalbaar alternatief
voor het maken van geneesmiddelen, niet
gebaseerd op geprivatiseerde monopolies maar op
het publieke belang.

Longshore sediment transport (LST) acts on beach morphodynamics on distinct temporal scales, being fundamental over sediment budget, and, so over the dynamic balance of coastlines. This study determined the most adequate methodology to estimate rates of non-cohesive sediments (from fine sand to gravel) transported by longshore currents, in the surf zone, under different meteoceanographic conditions, at the southern coast of Rio Grande do Sul (RS), Brazil. The methods proposed by CERC (Shore Protection Manual,

Nourishment and retreat are competing policy options for managing Delaware's eroding ocean beaches. We compare the costs of these tWo options over the next 50 years and find that the cost of retreat exceeds the cost of nourishment by more than a factor of three. The analysis ignores envUonmental considerations and, as always, rests on a number of assumptions presented within. Although the methodology is transferable to other areas, the results are noL

Background: Google Earth images were widely used to remotely study the natural phenomena such as wave diffraction. Breakwaters are built in Ras El-bar to protect the shore line against erosion and make the sea water suitable as harbors. Unfortunately through Google Earth, it became evident that the shape of the beach has changed behind the breakwaters. It took the shape of a decaying sinosoidal form. Headlands and bays are formed along the coast behind the breakwaters. Objective: Google earth images are used to calculate the sizes of the breakwaters, the distances between the breakwaters and the shoreline and the shapes of the shoreline. Then, Huygens Fresnel Diffraction formula is used to study why the shape of the shore line at Ras El-bar has changed in this way. Results: The intermediate spaces between the breakwaters act as slits which diffract the incoming water waves according the wavelength of the wave. Energy of water waves is maximized on the beach when the wavelength is mu...

The Corinth Canal is an emblematic technical project that integrates multiple dimensions: technological, historical, cultural, aesthetic, economic, social and political. Although the vision for its creation has existed since ancient times, it was realized in the early industrial era, reflecting centuries of ambition and transformation. Its impressive physical form and symbolic significance make it hypervisible, but its limited use and operational problems highlight the precariousness of big infrastructures. The canal is not only a technical achievement, but is transformed into a field of social, cultural and symbolic processes as it is approached as a socio-technical whole, where the infrastructure is transformed into active knowledge and performance, for the local communities at its eastern side (Isthmia-Kalamaki and Kyras Vrysi), as a meeting place where collective memory and imagination, local and national identity and cultural flows are condensed, social relations and policies. Through ethnographic methodology, the canal and the surrounding communities are treated as a whole, highlighting not only the historical conditions and policies that shaped the project but also its multiple dimensions and ramifications in the modern world.  -//- Η διώρυγα της Κορίνθου αποτελεί ένα εμβληματικό τεχνικό έργο που ενσωματώνει πολλαπλές διαστάσεις: τεχνολογική, ιστορική, πολιτισμική, αισθητική, οικονομική, κοινωνική και πολιτική. Αν και το όραμα για τη δημιουργία της υπήρχε από την αρχαιότητα, η υλοποιήθηκε στην πρώιμη βιομηχανική εποχή, αντανακλώντας αιώνες φιλοδοξίας και μετασχηματισμού. Η εντυπωσιακή φυσική της μορφή και η συμβολική της σημασία την καθιστούν υπερορατή, όμως η περιορισμένη χρήση και τα προβλήματα λειτουργίας αναδεικνύουν την επισφάλεια των μεγάλων υποδομών. Η διώρυγα δεν είναι μόνο τεχνικό επίτευγμα, αλλά μετατρέπεται σε πεδίο κοινωνικών, πολιτισμικών και συμβολικών διεργασιών καθώς προσεγγίζεται ως κοινωνιοτεχνικό σύνολο, όπου η υποδομή μετατρέπεται σε ενεργή γνώση και επιτέλεση, για τις τοπικές κοινότητες στο ανατολικό στόμιό της (ΙσθμίαΚαλαμάκι και Κυράς Βρύση), ως χώρος συνάντησης όπου συμπυκνώνονται η συλλογική μνήμη και φαντασία, η τοπική και εθνική ταυτότητα αλλά και οι πολιτισμικές ροές, οι κοινωνικές σχέσεις και οι πολιτικές. Μέσω της εθνογραφικής μεθοδολογίας, η διώρυγα και οι γύρω κοινότητες αντιμετωπίζεται ως ενιαίο σύνολο, αναδεικνύοντας όχι μόνο τις ιστορικές συνθήκες και τις πολιτικές που διαμόρφωσαν το έργο αλλά και  τις πολλαπλές της διαστάσεις και τις προεκτάσεις της στον σύγχρονο κόσμο.

This paper investigates the collapse and recovery processes of the sand spit at the Tenryu River mouth on the Pacific Coast of Japan, when two characteristic typhoons, Man-Yi and Fitow, passed over the study site in the year 2007. Although these two typhoons caused equally high storm waves, these two events were different in principal wave directions and in the amount of river discharges. As a result, Man-Yi collapsed the sand spit, while Fitow rather enhanced the recovery of the sand spit. Successive still images recorded by six field cameras were analyzed to investigate the dynamic morphology change of the river mouth for 2 months during which these two events had occurred. Comparisons of obtained topography changes and various hydrodynamic characteristics yielded several findings: (i) the sand spit was breached approximately 6 h after the peak of flow velocity and 2 h after the peak of the water head difference across the sand spit; (ii) the breached part of the sand spit was refilled by wave-induced shoreward sediment transport; and (iii) a core sample showed three clear layers of graded sedimentary structures of gravel, which correspond to the number of observed high waves overtopping the sand spit.

Due to the inherent randomness of environmental, hydraulic, and structural parameters, the safe design of rubble-mound berm breakwaters requires probabilistic approaches and reliability-based analyses. This study presents a comprehensive probabilistic assessment of rubble-mound berm breakwaters, emphasizing the influence of correlations and interactions among environmental variables. The primary objective was to evaluate failure probabilities over the service life of the structure by exploring different dependency structures among environmental parameters and assessing available empirical formulas for two major failure modes: berm recession and overtopping. Four dependency structures-independence, Gaussian copula, Frank copula, and D-vine copula-were used to model parameter correlations. Reliability assessment was conducted using FORM, SORM, and Importance Sampling methods, with performance compared against benchmark Monte Carlo Simulation (MCS) results. A case study on the rubble-mound berm breakwater at Tombak Port employed multiple empirical formulas for both berm recession and overtopping failure modes. Results demonstrated that, under the D-vine structure, the Torum (2007) formula yielded the lowest failure probability (28.9%), while Hall and Kao (1991) reported the highest (72.01%) for berm recession. Correlation structures significantly influenced outcomes, with a maximum observed difference in failure probability of 4.94%. For overtopping, five empirical formulas were analyzed, with Van der Meer and Janssen (1994) showing the lowest failure probability (27.99%) and Van der Meer and Sigurdarson (2012) the highest (69.56%), while the remaining formulas produced results between 45% and 67%. Sensitivity analysis using the FORM method showed that wave height and wave period are generally the most significant load parameters, while the density and mass of the armor layer stones are the most critical resistance parameters. Moreover, considering the correlation between environmental parameters brings the order of importance closer to physical reality and highlights that accounting for correlations and the statistical characteristics of variables is essential when assessing failure probability.

Details are given herein of the development and application of a three dimensional layer integrated numerical model to predict geomorphological changes in estuarine and coastal waters. An Alternating Direction Implicit finite difference scheme has been used for solving the governing differential equations, which include the conservation of mass and momentum for flow, the transport equation for suspended sediment fluxes and mass conservation for bed level changes. Model predictions, have been compared to predictions using other existing models and against laboratory measurements. A series of experiments have been carried out for a laboratory model harbour, with the model predictions being compared to laboratory measurements.

A technique for internal generation of waves is studied for two time-dependent mild-slope w equation models developed by Copeland Copeland, G.J.M., 1985. A practical alternative to the x w mild-slope wave equation. Coastal Eng., 9, pp. 125-149 and Radder and Dingemans Radder, A.C., Dingemans, M.W., 1985. Canonical equations for almost periodic, weakly nonlinear gravity x waves. Wave Motion, 7, pp. 473-485 . For the Radder and Dingemans' equations, desired energy of incident waves could not be obtained from the viewpoint of mass transport which has successfully been used for the Boussinesq equations and the Copeland equations by Larsen and w

Can 're-wilding' at 'earthquake disaster remains (shinsai ik o)' introduce a new paradigm of memorializing the 2011 Great East Japan Earthquake and Tsunami? What sacrifices do conventional formulas of memorialization and heritagization demand of the 3.11 tsunami-affected residents and municipalities? This paper explores these questions by examining two atypical 'earthquake disaster remains' in Miyagi Prefecture: the former police box in Onagawa, and the concrete foundations of housing in Arahama. Brimming with vegetal desires for life, the two sites look viscerally chaotic and alarmingly unkempt, defying most people's expectations. My analysis shows that conventional formulas of memorializing the sites of trauma require vigilance against weathering and decaying, lest changes in appearance threaten the authenticity of the sites. In this context, by foregrounding the earthquake disaster remains' physical mutability through ecological entanglement, I argue, the two atypical sites under investigation distill the inherent contradictions and problematics that our ingrained practices of memorialization take for granted. Through re-wilding, what I call 'partial forgetting by design', will emerge as a possible intervention into imagining a life and future in the disaster-prone areas around the world in an era of planetary climate change.

Space infrastructures are becoming increasingly important to the global society and economy. However, their cybersecurity is understudied despite previous endeavors. This motivates the present SoK, which is based on a novel methodology of five elements: space infrastructures model, missions, vulnerabilities, attacks, and defenses. The methodology establishes an "anatomy" of space infrastructures via the innovative notions of mission control flows and mission data flows, which are respectively inspired by the notions of control flows and data flows in program analysis. We show how the space infrastructure vulnerabilities, attacks, and defenses studied in the literature can be mapped to space mission control flows and mission data flows, leading to insights such as: improper memory allocation and lack of authentication are the two most exploited vulnerabilities reported; Global Navigation Satellite Systems (GNSS) security is most studied, mainly via physical layer security; and the most effective approach to attack the space segment is to pivot through the ground segment.

The rehabilitation and reconstruction program in Central Sulawesi has a different circumstance with the precedent in NAD-Nias, although using the same method, but somehow facing almost similar challenges. The legal basis for Central Sulawesi does not regulate the community-based in implementing rehabilitation and reconstruction program like the precedent, but more like centralized on the Ministry of Public Work and Housing instead (Top-Down Approach). However, as written in the Indonesian constitution, the main guideline for rehabilitation and reconstruction acknowledges decentralization of power from central to local government. It mentions two schemes to implement the rehabilitation and reconstruction program, that is community-based and contractual schemes.
This research examines a practical policy implementation approach in housing rehabilitation and reconstruction in Indonesia. The study uses a qualitative method through documentary research with the data from the Disaster Management Task Force for Central Sulawesi. It examines the implementation style of rehabilitation and reconstruction policy in permanent housing, the contribution of the implementation style in achieving disaster resilience, and the challenges in implementing the policy.
The research uses public policy theory on policy implementation, and the disaster resilience concept on the theoretical framework concluded that the rehabilitation and reconstruction in Central Sulawesi uses a combination of Top-Down and Bottom-Up Approaches. The approaches help generate lessons learned, awareness, and improvement in preparing and making Central Sulawesi resilient to future disasters. However, the two approaches still need to deal with obstacles and challenges in land acquisition, social issues, and design and planning.

Sedentary and mobile organisms grow profusely on hard substrates within the coastal zone and contribute to the deterioration of coastal engineering structures and the geomorphic evolution of rocky shores by both enhancing and retarding weathering and erosion. There is a lack of quantitative evidence for the direction and magnitude of these effects. This study assesses the influence of globally-abundant intertidal organisms, barnacles, by measuring the response of limestone, granite and marine-grade concrete colonised with varying percentage covers of Chthamalus spp. under simulated, temperate intertidal conditions. Temperature regimes at 5 and 10mm below the surface of each material demonstrated a consistent and statistically significant negative relationship between barnacle abundance and indicators of thermal breakdown. With a 95% cover of barnacles, subsurface peak temperatures were reduced by 1.59°C for limestone, 5.54°C for concrete and 5.97°C for granite in comparison to no ba...

As well as their destructive roles, plants, animals and microorganisms contribute to geomorphology and ecology via direct and indirect bioprotection, which can reduce weathering and erosion. For example, indirect bioprotection can operate via biotic influences on microclimate whereby physical decay processes associated with fluctuations in temperature and moisture (salt crystallization, thermal fatigue and wetting-drying), are limited. In the intertidal zone, the spatial and temporal distribution of macroalgae (seaweeds) is patchy, related to physical and ecological conditions for colonization and growth, and the nature and frequency of natural and anthropogenic disturbance. We examined the influence of seaweed canopies (Fucus spp.) on near-surface microclimate and, by implication, on conditions for mechanical rock decay and under-canopy ecology. Monitoring on hard artificial coastal structures in South West England, UK, built from limestone and concrete showed that both the range and maxima of daily summertime temperatures were significantly lower, by an average of 56% and 25%, respectively, in areas colonized by seaweed compared to experimentally cleared areas. Short-term microclimatic variability (minutes-hours) was also significantly reduced, by an average of 78% for temperature and 71% for humidity, under algal canopies during low-tide events. Using seaweed as an example, we develop a conceptual model of the relationship between biological cover and microclimate in the intertidal zone. Disturbance events that remove or drastically reduce seaweed cover mediate shifts between relatively stable and unstable states with respect to mechanical decay and ecological stress associated with heat and desiccation. In urban coastal environments where disturbance may be frequent, facilitating the establishment and recovery of canopy-forming species on rocks and engineered structures could enhance the durability of construction materials as well as support conservation, planning and policy targets for biodiversity enhancement.

Purpose Environment-friendly management of sites used for disposal of locally generated sedimentary material involves designation of an optimal dumping site location which will render the dredged material re-usable for beneficial purposes. The objective of this research was to determine whether wind, waves, and currents can induce transport of sediment from offshore dumping sites located at intermediate depths in the southern Baltic. The problem was addressed by exploring potential sediment transport from two sites located in the Gulf of Gdańsk at depths of about 20 m. A total of 29 combinations of hydrodynamic variables, representing the most extreme possible situations in the area, including eight theoretical uniform wind fields over the entire Baltic Sea from the W, NW, N, NE, E, SE, S, and SW sectors, the wind speed of 30 m s -1 , as well as 21 historical extreme storms, retrieved from the HIPOCAS project database, were used. The bottom velocities resulting from waves and currents at the dumping sites considered were computed using wave models (WAM, SWAN) and the M3D hydrodynamic model (based on the POM model). To estimate the velocities critical for bedload transport, formulae developed by Soulsby (1997) and Sawamoto and Yamashita (Proc Coastal Sediments 87:415-423, 1987) were used. The volumetric bedload transport was computed based on . The model simulations demonstrated that, for the storm conditions analyzed, the current velocity in the area of the two dumping sites would be so low that it would practically not affect the magnitude of the bottom sediment transport. Thus, the resultant volume of bedload transported would be equal to that generated by the wave action. For the heaviest historical storm, the maximum transport is about 3 × 10 -5 m 2 s -1 . Conclusions Under conditions of theoretical storms, the bottom orbital velocities would be higher and the resultant sediment transport would reach almost 7 × 10 -5 m 2 s -1 for northerly winds. However, this value is still very low compared with the volume of sediment being dumped. The findings of this study may prove useful in designation of future dumping sites.

We present a simple one-dimensional process-based morphological model for predicting medium-long term beach profile evolution of a bayside beach with a low tide terrace. Bayside beaches are characterized by low wave energy. In regions with large tidal ranges, a beach face is slowly eroded due to erosional waves inside the surfzone which shifts along the beach profile over a wide range during a tidal cycle. The model used in this study was initially developed by Mariotti and Fagherazzi (2010) who formulated sediment suspension and transport due to waves and tidal currents in a tidal flat regime. Modifications are made for modeling beach profile evolution caused by small waves and tidal currents, which are similar to dynamic forcing in a tidal flat system. The model is validated using beach profile data collected over one-year span at Xiamen Beach. Numerical experiments suggest that a combination of wave and tidal forcing makes an erosion of the upper steep

Existing dissipation models (bulk and frequency distributed) describing the wave attenuation in canopies rely on a characteristic shape of the velocity profile and corresponding characteristic frequency, which is integrated analytically over the height of the canopy. This means that all frequencies higher than the characteristic peak frequency are assigned excessive dissipation, while all frequencies lower than the characteristic peak frequency are assigned insufficient dissipation. The present work presents a new dissipation model, which is given in a closed form based on the surface elevation spectrum, S η . The model calculates the frequency dependent dissipation at a given vertical elevation z, which is numerically integrated over the height of the canopy. A comparison with existing bulk dissipation models shows that there are large differences between the existing models and the present work. These differences are particularly noticeable for realistic peak enhancements factors for the JONSWAP spectrum (1.0-10.0) and submerged canopies. A comparison with the frequency distributed dissipation model in the spectral wave model SWAN is also presented and the present model distinguishes itself by naturally incorporating a cut-off frequency above which the dissipation effectively vanishes. This offers a more realistic frequency distribution of the dissipation. The frequency distribution of the dissipation and the existence of a frequency cut-off is verified with experimental data.

This paper presents a laboratory study on wave transmission across steep platform reefs, aiming at furthering knowledge of wave hydrodynamics and establishing empirical formulations of spectral wave parameters across the reef flat. The ultimate aim of this study is to determine the design wave load to design fixed offshore structures on coral reefs flat. The process of wave transmission across the underground coral strip with a large front slope has been studied on a physical model in the wave trough with nearly 300 experimental cases combined from 05 underground band models and many random wave scenarios and scenarios at different submerged depths. Experimental results show that the abrupt transition in depth from deep water ahead to relatively shallow water in the reef is responsible for the difference in the wave at the top of the strip compared to the wave on the normal beach, especially regarding the statistical distribution of the wave height. Breaking waves at the abrupt transition have deviated the wave height distribution curve from the deep-water (Rayleigh) theoretical distributions and even the existing shallow-water distributions, including the effect of breaking waves. Two sets of empirical formulations of the spectral wave parameters (Hm0 and Tm-1, 0) are eventually derived for the surf zone and the region behind the surf zone, respectively. These local wave parameters can be used as inputs to a wave height distribution model for determining other design characteristic wave heights on steep platform reefs.

As noted by several researchers, the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile River is expected to have unfavorable consequences for downstream countries like Egypt and Sudan. To limit GERD's negative effects on downstream countries, its operation should be secure, and its upstream water level should be ideal. However, none of the studies carried out the ideal operating scenarios from the perspective of controlling the number of gate openings. Accordingly, this study evaluates the optimal operating scenarios of the GERD and its impact on downstream countries by adopting a mathematical model to analyze the number of gates that can be opened and the depth of opening during different filling years. The paper also presents an environmental impact assessment of some GERD significant factors during construction, filling, and operation, with the goal of developing a mitigation strategy. The results showed that opening 5 gates at 4.56 m over a 10-year filling period would be the safest, most accepted, and most advantageous for Ethiopia and downstream countries. Moreover, creating a water-saving management plan in Egypt to overcome GERD's negative impacts would cost 877 billion Egyptian pounds.

A computer intensive statistical procedure known as the bootstrap has been used to estimate the error in coastal stage-frequency relationships due to uncertainties in hurricane meteorological distributions. These stage-frequency relationships are developed through the use of a joint probability method, so that the probability of a storm event is the product of the probabilities of the individual independent components which comprise that storm event. The bootstrap technique provides an estimate of the error of the stage-frequency by determining the variation possible in each component's probability distribution. This variability is due to the construction of the distribution from a finite set of historical events. An example of the bootstrap is given and stagefrequency results and error estimates typical of a coastal region are shown.

Reliable estimates of coastal flooding from tides and storm surges are required for making sound engineering decisions regarding the design, operation and maintenance of many coastal projects. A recent investigation of flood frequency along the coast and within the bays of southern Long Island, New York, produced new and optimal approaches to obtain meaningful statistical estimates of flood levels. This paper summarizes various elements of the study and concentrates on the problem of stage-frequency computations in the inland bay areas. Methods for optimizing the number of necessary storm/tide simulations and estimating the accuracy of results are presented.

Wave induced pore pressure and instantaneous liquefaction are known to occur and cause loss of bearing capacity of sand. Wave bottom pressure p forms the boundary condition for the wave induced pore pressure. It is believed that not only variation of the pressure itself, but also the variations of its first and second order spatial derivative play an important role in the formation of liquefaction. An experimental and a preliminary numerical study on unidirectional water wave propagation over a bar are presented. Emphasis is placed upon investigation on the wave induced pressure gradient at the seabed. Single sinusoidal, two-component sinusoidal and five-component sinusoidal waves are investigated in a wave flume of constant water density p. Only the results for single sinusoidal waves are reported herein. The variation of the dimensionless pressure gradient C p = (dp I' 3c) I'{pg) was within ±0.4 for all experiments with a tendency of larger values for downslope gradients (negative values) than for upslope. (g is the acceleration gravity). The numerical results, based on the two-dimensional Green-Naghdi theory for fluid sheets -level II, compare well for sea bed pressures and gradients, but the sea surface does not fit the observations so well.

This research is designed to find out w ave transmission coefficient Kt for three different models of pile breakw aters in coast al area. The selected breakw ater models are: pile breakw ater, horizontal rectangle strips fixed to piles, and horizontal c-channel strips fixed to piles. Experimental tests w ere conducted under perpendicular regular w aves w ith various w ave characteristics and pile breakw aters geometry. The considered dimensionless parameters are w ave steepness Hi/gT 2 , relative spacing betw een piles G/D, relative spacing betw een row of piles ¢ to ¢ S/D, relative spacing betw een strips C/W, and arrangement of strips A. The results depicted that Kt decreases w ith the increase of Hi/gT 2 , S/D, and w ith the decrease of both G/D and C/W. The performance of model 1 w as improved by adding horizontal c-channel strips with staggered arrangement and w hich resulted in decreasing Kt value by about 24.7 %. Empirical relations w ere derived by analyzing experimental data. This technique can be utilized to predict the performance of the selected models for different w ave characteristics and models geometry. Also there are reas onable agreement betw een results of selected model and other previous similar studies.

The Egyptian government is grappling with the challenge of sedimentation in Damietta Harbor (DH), leading to expensive and recurring dredging operations for safe vessel navigation. This research examined the changes in the region's coastline, both before and after the port was established between 1977 and 1995. The impact of the government's policy to halt backfilling in the navigation lane on adjacent beaches until 2023 was also assessed using remote sensing (RS) and the Digital Shoreline Analysis System (DSAS) program, revealing varying yearly accretion and erosion rates. Following a shoreline movement tracking procedure, in the period from 1985 to 2023, the total areas undergoing erosion and accretion amounted to −1.36 km2 and +2.21 km2, respectively.
To address the issue, the research team developed scenarios reflecting regional realities and conducted a numerical simulation using the Coastal Modeling System (CMS). Morphological alterations in the approach channel and pre- and post-port regions were monitored to assess the scenarios. The study also explored how deepening the navigation channel affected the annual sediment volume. Results showed that Scenario 5, involving breakwaters extension and the new western breakwater (NWBW), effectively controlled sediment. However, sedimentation increased with the deepening of the navigation channel. Scenario 7, with a 19 m deepening, exhibited slightly higher sediment volume by 21.75% but stood out for its capacity to handle large vessels. Additionally, the sedimentation in the navigation channel experienced a notable 72.1% decrease in Scenario 8, which portrays the anticipated final state of DH compared to the benchmark case.
The study noted morphological changes from planned coastal constructions on the eastern side, including detached breakwaters (DBW) and Y-groins (Y-gs). Despite significant development costs, these structures were deemed insufficient to stabilize the shoreline. In summary, the research highlights the complexity of addressing sedimentation in DH, emphasizing the need for nuanced approaches in coastal management, and considering the consequences of deepening navigation channels.

The geomorphological and ecological response of the ebb tidal deltas of the SW Netherlands to implementation of the Delta Project during the last decades, has been the subject of an integrated research project. General observed geomorphological trends are: erosion of the delta fronts and of the relic tidal bars in the landward parts of the deltas, and sedimentation in the tidal channels and in longshore bars at the edges of the deltas. Ecologically, a general trend towards richer benthic fauna communities is observable. The integrated approach in coastal research combining geomorphological analysis of field data with numerical modelling, and integrating hydraulic, geomorphological, sedimentological and biological data, has appeared very promising. Progress in this field would be stimulated by further research of the driving processes in the interaction of hydrodynamics -sediment -biota. The level of detail (spatial and temporal)' in geomorphological contributions to such research will have to be much higher than usual in current coastal morphological studies.

This research was conducted by equipping three temporary tidal stations located in three places inside Palu Bay with pressure-type tidal gauges. The stations recorded tidal series fluctuations for 4 months with a 5-minute sampling interval (Dt). Moreover, the simple and widely used least squares method (LSM) was applied to separate the harmonic constants of constituents, including amplitudes (Hi) and phases (gi), from the observed tidal series. A total of 11 dominant constituents were selected based on the largest magnitudes of tidal generating potential (CE), and these include M2, K1, S2, O1, P1, N2, Mf, K2, Mm, Q1, and Msf, which were diurnal, semidiurnal, and long-period constituents. The results showed that the semidiurnal constituents generated higher amplitudes than the diurnal constituents, while the long-period constituents produced quite small amplitudes. Furthermore, the ratios of amplitudes recorded showed that tidal in Palu Bay was mainly mixed with semidiurnal constituents. The difference between the observed and predicted values was quite small, and this showed the validity of the measurement conducted at the temporary tidal stations. The performance indicators applied also showed that LSM had acceptable accuracy compared to other methods. Moreover, tidal datums were calculated using the peak approach, and the average tidal range (RA) of Palu Bay was found to be 2.39 m.

The European Union funded project DELOS was focused on wave transmission and an extensive database on low-crested rubble mound structures was generated. During DELOS, new empirical wave transmission formulae were derived. These formulae still showed a considerable scatter due to a limited number of parameters included. Neural networks based on a homogeneous database have resulted in a useful prediction model for wave overtopping within the EU project CLASH. The successful methodology of CLASH is applied within this study. The aim of this study is to improve the prediction of wave transmission in comparison to the empirical DELOS formulae with help of a prediction model based on neural networks. This paper gives a overview of the contents of the composed homogeneous database and gives insight in the capacity and accuracy of the final prediction model. The final prediction model includes 9 input parameters, which is more than at present in the existing hand-derived empirical formulae. The prediction model is accurate in predicting wave transmission for both smooth and mound lowcrested structures.

One of the main objectives within the EU-project CLASH (www.clash-eu.org) was to create a generic prediction method for wave overtopping at coastal structures by means of the Neural Network technique. An extensive and homogeneous database on wave overtopping was set up within CLASH, mainly with the aim to be used for the training process of the Neural Network (NN). A total number of 10,532 tests from 163 independent test series were screened and included in the database. The final database consists of far more information than needed for the training of the NN: 31 parameters are included to describe each overtopping test of which only 17 are used for the NN development. This explains the possible use of the overtopping database on its own. Plotting various parameters of the database together in graphs gives a clear view on the contents of the database. Also the ranges covered by the parameters can be detected in this way. The creation of the database, the analysis of the database, and the possible use of the database on its own are described in this paper.

This study aims to enhance the seismic stability of rubble mound breakwaters, crucial maritime structures, by examining how variations in the rear slope angle affect their response to seismic loads. Utilizing the Plaxis 2D software, a finite element method was employed to simulate the behavior of a conventional rubble mound breakwater under different seismic conditions. The analysis considered three different rear slope angles and subjected each to various seismic loads characterized by differing amplitudes and frequencies. Our findings indicate that the rear slope inclination significantly influences the seismic response of the breakwaters, notably affecting the displacements and deformations within the structure. The most optimal angle of inclination was identified, which minimized the seismic-induced deformations, thereby potentially improving the structural integrity and longevity of these maritime defenses. This investigation not only provides valuable insights into the design of more resilient maritime structures but also introduces an approach to optimize breakwater design for better performance under seismic conditions, marking a notable improvement in the field of maritime engineering.

A breakwater is a structure designed to protect coastal areas by breaking and reducing the force of incoming waves. Waves that propagate through a wave dampening building will have some of their energy reflected (reflection), some of their energy transmitted (transmission), and some of their energy destroyed (dissipation). The effectiveness of wave-breaking structures in protecting coastal and harbor waters can be seen from how much wave energy the building can reduce. In this research, the performance of the wave breaker will be seen from the values of wave transmission (Kt) and wave reflection (Kr) with an inclined pile building structure. Reflection and transmission analysis of the results of 2D physical model testing of wave breakers with inclined pile structures are needed to optimize their use. Laboratory test results prove that this Inclined Pile Structure breakwater is quite effective in scenarios that have smaller Kt values and larger Kr values. In this experiment, testing was carried out with several parameters, namely the slope of the pile, the distance between the piles in one row (or distance between pillars), the distance between the tops of the piles (or distance between rows of piles), and the depth of the water. The Kt value in the model α=45°; D=1.69 cm; b=5 cm is 0.603 compared to the model α=60°; D=1.69cm; b=5 cm, Kt value is 0.652. This shows that the inclined pile structure of breakwater is more effective with a pile slope of 45° than with a pile slope of 60°.

We investigate the vertical, wave averaged distributions of shear stresses and Eulerian flow in normally incident, shoaling and breaking waves. It is found that shear stresses are solely due to wave amplitude variations, which can be caused by shoaling, boundary layer dissipation and/or breaking wave dissipation. The resulting shear stress and mean flow distributions for these cases are derived, and compared with earlier work. The attractive, now frequently used modelling choice of specifying a shear stress at the mean surface level is discussed in the context of the constituent equations and related boundary conditions and constraints. A derivation of the shear stress at the mean surface level is given both by using the momentum balance and energy balance equations, which is shown to lead to the same result, if the effects of a changing roller are incorporated correctly 3 ). Finally, matching solutions for the shoaling and breaking wave cases between the boundary layer and the middle layer for the shear stresses and the wave averaged flow are derived.

The interaction between the constituent models for waves, currents, sediment transport and bottom level changes in a class of compound 2DH mathematical models of transient sea bed evolutions in the coastal zone is investigated mathematically, using the theory of characteristics and a harmonic analysis technique. This leads to contrary indications as to the importance of including diffraction in the wave model and to the unambiguous conclusion that the bottom slope effect on the sediment transport is indespensable for the mathematical system to be inherently stable. This conclusion is shown to imply that depth-integrated current model are insufficient to describe the flow in this type of morphological computations for the nearshore zone or complex coastal areas.

A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive flow, water level, salinity and suspended sediment data shows a good representation of observed phenomena. With the present calibrated and validated model, the residual flow field and the residual sediment transport field are obtained. The residual sediment transport pattern gives insight into the morphological behaviour of the mouth bars. 1

This paper describes the components of numerical modelling the influence of beach nourishment, and the concept of an optimal design of such measurements. The mathematical-numerical model consists of three components of waves, currents and sediment transport (including beach change). The wave transformation module is based on a new hyperbolic formulation for monochromatic waves, the current module is horizontally two-dimensional, and the sediment transport describes suspended as well as bed loaded transport. In the second part of the paper we describe a systematical path to optimize the effects of beach nourishments. Starting from an ideal bathymetry we could reduce the space of parameters and studied the principal effects of some geometrical forms and locations. An example of an experimental beach nourishment shows the practicability of this path.

Shoreline segmentation is a specialized water-land segmentation task that detects the position of the shoreline. Existing datasets for segmentation either do not focus on coastal environments (e.g., DeepGlobe) or are not based on high-resolution imagery (e.g., Sen1Floods11). To fill this gap, we built Coastal Aerial Imagery Dataset (CAID), a high-resolution, manually labeled benchmark dataset built on aerial imagery for shoreline segmentation. CAID consists of 20,689 images of 500 × 500 pixels across 850 NAIP sites across the Great Lakes region. The dataset covers a variety of coastal landscapes and its representativeness of coastal environments was evaluated using three criteria: water body area, shoreline length ratio, and mean water hue. We also assessed the benchmark performance of existing segmentation models on CAID. While these models achieved high mIoU and mAcc scores, accurately positioning shorelines remains a challenge, a limitation that is not fully reflected by existing evaluation metrics. To address this, we introduced mean shoreline covering ratio (mSCR), a novel metric that quantifies each model's ability to align with ground-truth shorelines. The CAID dataset, along with the associated code for training and evaluating deep learning models, will be publicly released under the CC-BY-4.0 license via GitHub and Zenodo to ensure open-access availability.