Coastal Structures Research Articles

Geodynamic hazard assessment for the archaeological park-museum by the town of Nikopol

This study was conducted to establish the engineering geological and hydrogeological conditions of the site and to assess the geodynamic hazard in relation to the design and construction of the archaeological park-museum and feeder road in the town of Nikopol (Bulgaria). The studied terrain occupies a river terrace and the foot of a delluvial slope with an elevation of 23-68 m. The tasks of the study are to identify: the geological structure of the slope, the area and depth range of the landslides, the location of the slip surface, the physical and mechanical properties of the engineering geological strata, the hydrogeological conditions, the current stability of landslides, the change of slope stability under the action of various factors. The ground investigation includes analysis of archival and published information on the area; geodetic survey of the landslide; engineering geological mapping; exploratory boreholes; geophysical surveys using the VES method; testing of soil and water samples; compilation of longitudinal engineering geological profiles and slope stability analysis using the computational models. To the south of the study site the slope is affected by an ancient landslide with a volume of about 30 million m3 developed on the right valley slope of the Danube River in the section between the plateau and the river terrace. Consistent landslides occur in its lower part. Slope stability calculations show that the landslides are triggered by a rise in the groundwater level, an earthquake and undermining of the slope base. Rock-falls has developed on the steep rock slopes, composed of moderately to highly weathered and fractured cherty and glauconitic limestones. The size of the rockfall blocks is in the range 0.3-0.8 m3 and their transport distance reaches from 10 m to 50 m from the base of the slope. Stabilization measures and facilities are proposed to strengthen the landslides and rockfalls in the considered section of the slope. For the landslides it is proposed to implement a counterfort embankment on which to build the feeder road, drainage ribs and drainage ditches. For protection of the buildings from collapsing rock debris, an anchored high-strength net is recommended. The design takes into account the trajectory of the falling blocks and their kinetic energy. For monitoring the condition of the landslides and rockfalls, as well as for evaluating the effectiveness of the implemented strengthening, drainage and coastal protection structures, a control and measurement system for regime observation was built.

Structural Performance of GFRP-Wrapped Concrete Elements: Sustainable Solution for Coastal Protection

Protecting coastal regions is crucial due to high population density and significant economic value. While numerous strategies have been proposed to mitigate scouring and protect coastal structures, existing techniques have limitations. This paper introduces a novel approach, SEAHIVE®, which enhances the performance of engineered structures by utilizing hexagonal, hollow, and perforated concrete elements externally reinforced with glass fiber-reinforced polymer (GFRP). Unlike conventional steel bars, GFRP offers superior durability and requires less maintenance, making it a sustainable solution for any riverine and coastal environment. SEAHIVE® aims to provide robust structural capacity, effective energy dissipation, and preservation of natural habitats. Although some research has addressed energy dissipation and performance in riverine and coastal contexts, the structural performance of SEAHIVE® elements has not been extensively studied. This paper evaluates SEAHIVE® elements reinforced with externally bonded GFRP longitudinal strips and pretensioned GFRP transverse wraps. Testing full-size specimens under compression and flexure revealed that failure occurred when the pretensioned GFRP wraps failed in compression tests and when longitudinal GFRP strips slipped in flexure tests. Strength capacity was notably improved by anchoring the GFRP strips at both ends. These findings underscore the potential of the SEAHIVE® system to significantly enhance the durability and performance of coastal and riverine protection structures. FEM simulations provided critical insights into the failure mechanism and validated the experimental findings. In fact, by comparing FEM model results for cases before and after applying GFRP wraps under the same compression load, it was found that maximum stresses at crack locations were significantly reduced due to compression forces resulting from the presence of pretensioned GFRP wraps. Similarly, FEM model analysis on flexure samples showed that the most vulnerable regions corresponded to the locations where cracks started during testing.

Prediction model for equivalent exposure time in indoor dry-wet cycling tests for concrete in marine tidal zones

Chloride ion erosion poses a major threat to the durability of concrete structures in coastal environments, particularly in tidal zones with periodic seawater exposure. This study developed a predictive model based on Fick's second law, utilizing data from over 20 coastal structures across six countries. The model, grounded in the principle of equivalent free chloride ion concentration at a certain depth after a given exposure time, estimates the number of dry-wet cycles required in accelerated laboratory testing to simulate real-world conditions. It has been validated using data from actual marine structures. Key environmental factors such as temperature and humidity, along with regional climate differences, are incorporated to predict the relative deterioration rates of concrete in various marine environments. Additionally, an accelerated indoor dry-wet cycle test was designed based on the theory of environmental similarity, tracking the performance evolution of concrete. The model was verified through experiments, showing that 30 indoor dry-wet cycles correspond to 79 years of exposure in a coastal environment. The physical property changes observed in the accelerated tests further confirmed the model’s reliability and accuracy. This research provides critical insights into the impact of environmental factors on concrete degradation and offers a scientific basis for the application of accelerated laboratory testing.

Isolation and Characterization of Ureolytic Calcifying Bacteria from Methane Hydrate-Bearing Marine Sediments for Bio-cementation Application

In bio-calcification, microbes precipitate calcium carbonate (CaCO3), forming versatile solid substances that promotes eco-friendly materials and reduce carbon emissions. Marine bacteria can generate bio-cements to strengthen dikes and combat coastal erosion. However, the role of marine bacteria in generating bio-cements for enhancing coastal structures and combating erosion is not fully understood. This study investigates the potential of CaCO₃ precipitating bacteria isolated from methane hydrate-bearing marine sediments. Five calcifying marine bacteria were isolated using Christensen's urea agar from marine sediments collected from Gawadar coastal, Pakistan. Bacterial strains induced CaCO3 precipitation producing urease enzymes. Strains were identified as Pseudomonas putida, Bacillus altitudinis, Vibrio sp., Bacillus sp., and Vibrio plantisponsor. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and X-ray diffraction were applied for the identification and differentiation of calcite and vaterite precipitates. The growth of isolates and precipitation potential were observed optimum at 5% NaCl and pH 9.5-11. Bacillus altitudinis (ST4SD3) and Bacillus sp. (ST4SD1) produced more soluble Ca2+ (8532.53 mg/l and 7581.98 mg/l) as compare to other isolates at higher pH 10 and pH 11, favorable for CaCO3 precipitation. It is concluded that marine ureolytic bacteria possess significant potential for bio-cementation, which can stabilize methane hydrate-bearing sediments, improve soil properties, protect coastal regions from erosion, and crucial in the methane cycle, a greenhouse gas. We recommend further exploration of such bacteria's applications in marine construction and sediment stabilization to enhance the robustness and longevity of coastal infrastructures. Furthermore, such bacteria could also be beneficial in extracting gas from unconsolidated methane hydrates containing sediments.

Shoreline Behavior in Response to Coastal Structures: A Case Study in Haikou Bay, China

The rapid development of coastal structures on sandy coastlines raises concerns about their impacts on the shoreline’s evolution and the sediment transport dynamics. This study utilized a numerical modeling approach to simulate the multi-year response of Haikou Bay’s coastline to various nearshore structures, including piers and a large artificial island. The LITLINE module of the MIKE21 (v2020) software was employed to analyze the sediment transport patterns across three distinct coastal segments. The simulation results indicated that the sediment transport directions varied significantly: from west to east in the western segment, from east to west in the middle segment, and convergence toward the center in the eastern segment, divided by a construction trestle. The net sediment transport rates were quantified as 2000 m3/year for the western segment, 8000 m3/year for the middle segment, and 13,000 m3/year (west) and 10,000 m3/year (east) for the eastern segment. Due to the conflicting sediment transport directions on each side of the breakwater, noticeable deposition occurred on both sides. The presence of the artificial island created notable deposition in its wave shadow area, while the overall impact on the shoreline changes diminished over time. These findings underscore the significant influence of human activities, particularly coastal structures, on the natural evolution of shorelines.

A multi-criteria decision-making model for sustainable selection of coastal protection structures

Although nature-based and hybrid (i.e., a combination of hard and nature-based) solutions provide well-documented benefits to both the environment and people living nearby, they cannot be implemented in all coastal zones. Thus, the selection process of coastal protection structures (CPSs) requires an in-depth and comprehensible assessment with an effective and robust decision-support framework. Existing frameworks in the literature, however, do not focus on the selection of nature-based solutions and environmental and social factors were not considered thoroughly in these frameworks. In this respect, this research aims to develop a decision-support model that guides decision-makers in selecting the most appropriate and sustainable CPSs. The framework was designed in a way that includes a variety of environmental and social factors along with economic and technical aspects. Then, fuzzy AHP and TOPSIS analyses were conducted to determine the relative importance of the selection factors and to select the most appropriate CPS. Factors such as sediment dynamics, geotechnical issues, construction cost, transportation and navigation effects, and technological know-how were among the top-rated factors. TOPSIS analysis results revealed that mangrove forests and artificial reefs were the top two most sustainable CPSs. The proposed framework can minimize the social and environmental impacts of CPSs and expedite the green transition in the coastal environment.

Group interaction effect on breaking wave forces on a vertical pile: Experimental tests and predictive models

Pile groups are extensively utilized as supports for many coastal structures, such as bridges, jetties, and oil production platforms. The problem of understanding the interaction effects within pile groups and predicting the breaking wave forces on them is considered in this paper, using experimental tests and machine learning-based predictive modeling. The restriction of previous studies on this important engineering problem is that the pile group arrangements considered are limited. Prediction methods are therefore developed only for specific pile group arrangements and do not incorporate the effect of the incident wave direction. In this study, to partially overcome this limitation, an extensive experimental investigation is conducted on 70 different pile group arrangements under six breaking wave conditions. Three pile group coefficients, characterized by the total, quasi-static, and dynamic forces, are introduced for a thorough assessment of the interaction effects within the pile group. First, the pile group coefficients for three basic arrangements (tandem, side-by-side, and staggered) are evaluated. The results reveal a sheltering effect in the tandem arrangement and an amplification effect in the side-by-side arrangement. However, the forces on the measured pile in the staggered arrangement resemble those on the isolated pile, with neither significant sheltering nor amplification effects observed. Then, the results for all arrangements highlight the significant effect of wave direction on the pile group coefficients for small inter-pile spacing. Finally, different machine learning algorithms are adopted to develop predictive models for the group coefficients. The XGBoost model demonstrates superior accuracy for predicting the total and quasi-static force coefficients, while the dynamic force coefficient remains challenging to predict accurately due to its stochastic nature.

Flood risk and overtopping assessment for an exposed coastal road

The coastal village of Vík is located on the South Coast of Iceland. The area is subjected to the full force of extratropical cyclones of the North Atlantic. The village beach is not a stable phenomenon, after a nearby volcanic eruption in 1918 it accreted by 500 m over 50 years but has eroded at similar rate since 1970, which poses increased flood risk in the area. There are plans to move the current ring road, that lies through the village, with one possibility of it running along the coast. A study was conducted using multivariate extreme value modelling to determine the desired coastal defences needed for the new road. The method in question uses a multivariate joint probability model to simulate variables that cause coastal flooding events. It generates a large sample of extreme ocean events based on a 52-year time series of hindcast data. The large sample of extreme events were then used to determine return periods for overtopping events and to determine a desired crest height for coastal defence structures. The study puts forth suggestions of improvements on current coastal defence structures and the design specification for defence structures along a planned road along the coast.

Influence of lithodynamics of coastal area on the safety of railway operation on the Tuapse-Adler section of the North Caucasus Railway

The present paper considers the railroad bed on the Tuapse-Adler section of the North Caucasus Railway (Black Sea coast) in terms of its protection from wave scouring. Aim. To evaluate the influence of coastal lithodynamics on the safety of the railway operation on the section under consideration. The paper describes lithodynamic processes in the sea coastal zone and demonstrates the influence of coastal protection structures produced on lithodynamics in general and on adjacent sections, as exemplified by a specific section of the coast (1907–1910 km). The study involves a retrospective analysis of the step-by-step construction of trapping structures, and sea groins without full-fledged dumping of beach-forming material into the inter-groin compartments. The investigation and analysis of satellite images of 1907–1910 km coast within the Vodopadny-Lazarevskoye section indicate that lithodynamic processes remained unconsidered during the intensive construction of bank protection structures, which led to the beach erosion and the emergency condition of the seawalls along 1909–1910 km section. The paper provides recommendations for considering lithodynamic processes in the construction of railway protection structures, thereby increasing the safety of the railway operation.

Numerical investigations of pedestrian overboard on a compound slope dike due to excessive overtopping waves

Wave overtopping under extreme weather conditions can pose a notable threat to the safety of pedestrians on coastal structures. In this paper, physical experiments and numerical simulations based on scale-down models were conducted in accordance with an actual person overboard accident, highlighting the flow characteristics and the fluid force exerted on the pedestrian by the overtopping and reflecting flow on the berm. The determinations of pedestrian instability under various conditions in the Qingdao incident are presented. The accuracy of the numerical wave flume was validated through a comparison with the experimental results. The findings disclose that under various wave height circumstances, the characteristics of overtopping flow are highly in line with the existing conclusions, yet the prediction for reflecting flows is not satisfactory due to the compound structures. The maximum reverse recoil force acting upon the pedestrian is far more prominent when compared to the impact effect of the head-on overtopping flow, which consequently leads to the pedestrians being washed away into the water. The safety of the pedestrian on the viewing berm under various incident wave conditions is analyzed and predicted by comparing with two approaches for the determination of the pedestrian instability, namely, water flow factors and mechanical analysis.

Statistical distribution of surface elevation by using quadratic forms of normal random variables

This paper is concerned with the statistical properties of surface elevation, which is crucial for the design and operation of marine and coastal structures and is helpful to the prediction of rogue waves. A semi-analytic quadratic model is proposed to describe the statistical distribution of surface elevation by using the theory of quadratic forms of normal random variables, in which the characteristic function and cumulants are given in analytical form, and the probability density is obtained by the numerical inversion of the characteristic function using the fast Fourier transform algorithm. Compared with Monte Carlo simulations, the quadratic model presents excellent performance in describing the probability density function of surface elevation, especially at the tails, for varying degrees of steepness, bandwidth, and directional spreading in both finite and infinite water depth. The effect of these parameters that characterize sea states on the statistical properties of surface elevation is also investigated. Through a comparative study, the quadratic model is superior to previously existing theoretical models.

Seascape Genetics and Distinct Intraspecific Diversification of the Decapod Nephrops norvegicus in the Adriatic Sea.

Norway lobster Nephrops norvegicus, a prized decapod crustacean species, is found at different depths across the East Atlantic Ocean and Mediterranean Sea. Despite management efforts, the stocks are globally characterised as overexploited. In the present study, the impact of biogeographical boundaries on the phylogeographical and demographic population status was investigated within the Adriatic Sea, addressing important genetic indices for decapod functional conservation management. Central Mediterranean, Adriatic Sea A total of 482 individuals of Nephrops divided into the 12 samples were collected across biogeographical range of the Adriatic Sea. Using the mtDNA D-loop and microsatellite markers, methods of phylogeography and seascape genetics were applied to infer offshore versus coastal population divergence, demography and structure. Significant findings include genetic differentiation between offshore and coastal samples, with higher diversity indices in open waters. The limited gene flow observed between these two areas emphasises the self-sustained nature of coastal populations. Recent demographic changes in coastal populations reflect geographical constraints, fishing pressures and fluctuations in self-recruitment success. Additionally, the study reveals historical biogeographic events shaping the Adriatic populations, with evidence suggesting lineage divergence during the upper Pleistocene and postglacial recolonisation from southern Adriatic refugia. The role of biogeographical conditions in shaping genetic structure and limited gene flow between inshore and offshore areas underscore the need for improved management strategies, emphasising the importance of marine protected areas in conserving coastal populations and maintaining overall genetic diversity of the Norway lobster in the Adriatic Sea. Genomic monitoring within current management practices is recommended.

Development of a smoothed particle hydrodynamics model for porous media flows with enhanced volume conservation and the revisit of the mass conservation equation

Porous media exist extensively in hydraulic and coastal engineering structures, while the modeling of wave/flow interaction with porous media remains challenging. This work develops a smoothed particle hydrodynamics (SPH) model for accurately simulating wave/flow interaction with porous media. The mass and momentum conservation equations incorporating the mixture theory are adopted. The resistant forces of the solid skeleton of porous media on fluid flows are described by the nonlinear empirical formula. The research contributions of the work lie in two aspects. First, two categories of mass conservation equations for porous media flow are revisited and analyzed to examine the influences of the local time derivative term of fluid volume fraction on simulation results. Second, the Volume Conservation Shifting scheme is, for the first time, introduced into SPH to enhance volume conservation for simulating porous media flows. The developed SPH model is validated by an analytical case of seepage flows in a U-tube with porous media and then applied to study four benchmark examples involving both saturated and unsaturated porous media, i.e., dam-break flow through a crushed stone dam, rapid seepage flow through a rockfill dam, solitary wave propagation over a porous seabed, and solitary wave propagation over a submerged porous breakwater. The morphological features and dynamic pressure heads of the porous media flows have been satisfactorily predicted, demonstrating the good accuracy and enhanced volume conservation of the developed SPH model.

Turbulence with associated kinetic energy budget in the region of wave-blocking formed over an obstacle

Turbulence characteristics in the region of wave-blocking over a submerged forward-facing obstacle is explored, and the results are compared with those of base-flow over the obstacle. Wave-blocking over obstacle is setup, adjusting the strong incoming flow with counter-propagating waves, and confirmed by linear dispersion relation. A variation in the flow is detected in three distinct segments: flow from the upstream, wave-blocking over the obstacle and the waves propagating from the downstream. The instantaneous velocity is recorded using a three-dimensional micro-acoustic Doppler velocimeter along the flow. Turbulence properties such as the mean velocity, Reynolds stress, turbulent kinetic energy, and associated coherent structures around the wave-blocking are discussed. Moreover, power spectral density, kinetic energy budget, and turbulence length- and time-scales are examined. The stress fractions to the total shear stress contribute higher for only flow than those of wave-blocking over obstacle. The power-spectral peaks at a fixed frequency for wave-blocking along lee side are greater than those of base-flow over obstacle. Kinetic energy budget for only flow over the obstacle is much higher than that of wave-blocking, indicating loss of energy due to wave-blocking. In the near-bed region, length-scale increases indicating the higher momentum and energy transfer. Increase in anisotropy plays significant role in the production. Results are valuable to ship sailing, design of coastal structures, and sediment transport.

Wave overtopping discharges at rubble mound structures in shallow water

Wave overtopping of coastal structures has been studied using physical model experiments with rubble mound breakwaters in shallow water. The mean overtopping discharge is determined for three different foreshore slopes and various hydrodynamic conditions. The hydrodynamic results confirm that energy is transferred to low-frequency waves in very shallow water and that the short waves are in phase with the lower-frequency waves in very shallow water. As a result, the extreme waves (e.g. 2% exceedance wave height) become relatively large in very shallow water due to the energy of the low-frequency waves affecting thereby the wave overtopping. To estimate the amount of energy at the low-frequency waves, an expression is derived which reasonably accurately predicts the low-frequency wave energy (RMSE of 0.06). Considering the non-dimensional overtopping discharge, the existing formulations for the non-dimensional mean wave overtopping discharge perform poorly to reasonably in shallow water with RMSLE ranging from 1.04 to 2.92. A parameter sensitivity study shows that the short-wave steepness, relative crest height and the low-frequency wave height are the most important parameters when predicting the mean overtopping discharge in shallow water. When including the short-wave steepness and relative crest height in an empirical formulation the RMSLE for the current dataset reduces to 0.69. A further increase in accuracy is found when the low-frequency wave height and 2% exceedance wave height are included (RMSLE 0.64).

Effect of Enteromorpha-diatom adhesion on mortar performance

With the development of the marine economy, seawater is becoming more eutrophic. The risk of green tides from Enteromorpha is rising, which adversely affects the service of coastal infrastructure structures. To better evaluate the influence of algae on the long-term service performance of the structural concretes in coastal infrastructure, this study investigates the law of Enteromorpha-diatom attachment and growth on the mortar surface and its influence on the microstructure and durability of mortar. The results show that: 1) at 15 days, diatoms appeared on the surface of the mortar and biofilm appeared，the time period of adhesion and germination of Enteromorpha spores on the mortar surface was between 60 and 75 days. 2) Within 60 days, the spores released by the Enteromorpha preferentially germinate on the edges and in the pores of the mortar specimen, which can create micro-cracks on the mortar surface. Calcium carbonate may be involved in the metabolism of algae. 3) The pore size of the mortar surface gradually increases in the presence of bio-organic acids, which can accelerate the decrease of pH on mortar surfaces and reduce the resistance of mortar against chloride ions. This study confirms that green tide outbreaks may reduce the durability of cementitious materials, and provides a practical guide in the timing of protecting coastal infrastructure structures during the period of green tide outbreaks.

ЭКОЛОГИЧЕСКИЕ ОСНОВЫ ВЫБОРА БЕРЕГОУКРЕПИТЕЛЬНЫХ СООРУЖЕНИЙ ПРИ РЕКОНСТРУКЦИИ ПЛЯЖЕЙ КРЫМСКОГО ПОБЕРЕЖЬЯ

The relevance of improving the methods of engineering and environmental survey of coastal protection objects is determined by their existing violations, which reduce environmental safety in general and create a danger for the organization of tourism on the coast. The purpose of the study is to substantiate the choice of bank protection structures during the reconstruction of the beaches of the Crimean coast in the conditions of recreational specialization of the region. The nature and extent of deformations of the coastal zone of the sea and shore protection structures on the coast of the Kalamitsky Bay of the Black Sea are described. The authors proposed the design and location of the breakwater, which will make it possible to more effectively cope with the damping of waves during a storm period compared to classical breakwaters. Materials and methods. The study of the state of coastal territories and the solution of problems of coastal protection structures is based on the theory of geomorphology of the surface and underwater parts of the coast, the regularities of the hydrophysical parameters of the sea in the coastal zone, and climatic and seismic conditions. The methods of field observations and experimental studies in the wave basin were used to take into account the influence of natural and anthropogenic factors on the ecological parameters of the coastal zone of the Crimean coast. Results. In 2022, a team of authors carried out a visual survey of the coast in the territory of the Bakhchisaray district of the Republic of Crimea with a total length of 11.5 km. from s. Coastal to with. Angular. As a result of the inspection, sections of the coast that are potentially dangerous to the health and life of people and are not suitable for normal use for recreational purposes were identified. Conclusions. Long-term field observations show that the creation of bank protection in certain local areas, having given only a temporary positive effect for these areas, can have a very negative impact on neighboring and even remote areas; that is why the issue of protecting the coast should be resolved at least on the scale of the coast of settlements, taking into account the conditions of a single system. The shape of the coast protection structure proposed by the authors can make it possible to more effectively dampen waves compared to classical rectangular breakwaters. However, when designing coastal protection measures, it should be taken into account that separate protection of small areas of eroded coastal territories within a large zone of eroded coast is ineffective, since adjacent unprotected shores will recede under the influence of a system of natural factors.

Resistance to acid, alkali, chloride, and carbonation in ternary blended high-volume mineral admixed concrete

The World Bank study predicts that 4 °C warming will bring high temperatures, sea-level rise, and saltwater intrusion to coastal areas, damaging coastal concrete structures. Increased CO2 from industrialization exacerbates this, necessitating durable, low-carbon concrete. Combined use of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as high-volume OPC replacements boosts performance while reducing concrete’s carbon footprint. In this perspective current study examines the durability of concrete against aggressive agents (H2SO4, MgSO4, NaCl, and CO2) causing premature deterioration of concrete structures. Initially, three cost-effective sustainable concrete mix designs were developed, incorporating 50% replacement of OPC with locally available supplementary cementitious materials, specifically FA and GGBFS. These mixes were then evaluated for their mechanical and durability performances. The impact of aggressive ions (SO4 2−, Cl−, and CO3 2−) was studied by examining the changes in mechanical performance and phase assemblages. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were used to estimate the phase compositions. Ternary blended concrete having 50% OPC+ 30% GGBFS + 20% FA exhibited optimal synergistic performance, enhancing pozzolanic and hydraulic reactions for better resistance to harmful ions. The sorptivity test confirmed that as the GGBFS content increased, the sorption rate decreased, indicating the higher reactive nature of GGBFS to that of FA. Deleterious compounds formed due to the action of SO4 2-, Cl-, and CO3 2- were identified to be ettringite (Ca6Al2(SO4)3(OH)12.32H2O, AFt) and gypsum (CaSO4.2H2O, Gy), Friedel’s salt (Ca4Al2(OH)12Cl2.4H2O, Fs) and polymorphs of calcium carbonate (CaCO3), respectively through TG mass loss curve. These results were corroborated by FTIR analysis, which showed predominant characteristic bands at 662 cm−1 for SO4 2−, 459 cm−1 for Mg–O stretching, 790 cm−1 for Al–OH bending, and 1431-1443 cm−1 for C–O, confirming the presence of the deleterious compounds.

Analysis of climate change and climate variability impacts on coastal storms induced by extratropical cyclones: a case study of the August 2015 storm in central Chile

ABSTRACT The projected increase in coastal risk requires a reevaluation of coastal risk reduction strategies. A multi-model approach is proposed to examine the variability of coastal storms influenced by climate change and El Niño Southern Oscillation (ENSO). To this end, the historic coastal storm of August 8 2015, resulting from a local extratropical cyclone (ETC) off the central Chilean coast, was analyzed through the coupling of the WRF atmospheric model, Delft3D FM (D-FLOW and D-WAVE modules), and EOT20 astronomical tide model. The results show that the characteristics of local ETCs are susceptible to regional temperature gradients associated with climate change and ENSO. The coastal storm of August 8 2015, presented a decrease in wave height and counterclockwise rotation of wave direction along the Chilean coast under the climate change scenario. Meanwhile, the ENSO scenarios under cold conditions generated a ETC track’s displacement toward the north, causing both an increase in wave height along the coast of the Antofagasta and Atacama regions and a decrease in wave height in the Valparaíso, O’Higgins, and Maule regions. Findings from this study emphasize the importance of considering dynamic design for coastal structures rather than traditional methods to adapt to changing storm patterns.

Performance of integrated FB and WEC for offshore floating solar photovoltaic farm considering the effect of hydroelasticity

The offshore floating solar photovoltaic (PV) farm deployed in the open sea could be subjected to large environmental loading due to waves or wakes from travelling ships. To reduce the motion of the solar farm, mitigation methods such as protection of the solar farm via floating breakwater (FB) could be deployed. The FB serves as a buffer between the floating farm and the incoming wave force, and as it attenuates the wave forces, this creates a sheltered zone on the leeward side of the FB. The energy generation from the solar farm could be further enhanced via the integration of attenuator-type wave energy converters (WEC) with the FB. This paper investigates the performance of the hybrid FB – WECs as a coastal protection structure cum wave energy extraction devices. The effect of FB on mitigating the hydroelastic response of the floating solar farm is investigated. Four types of FB, i.e., I-, L-, U- and BOX-shape FBs are considered and their effectiveness in wave attenuation under regular waves arriving from different directions are studied. In addition, due to the long structure length-to-wavelength ratio of the floating solar farm and FB, the hydroelastic response of the structures is taken into consideration.