High Wave Energy Research Articles

Hydrodynamic conditions of Posidonia oceanica seagrass berm formation and dismantling events.

Seagrass berms are a natural accumulation of seagrass leaves along the shoreline, which play an important role in coastal protection. Seagrass berms have been shown to reduce wave energy, helping to shield the coast from erosion. However, their protective role is debated in coastal management, where there are contrasting views on whether berms should be left in place or removed to improve beach aesthetics or accessibility. Although seagrass berm accumulation and erosion are a globally recognized phenomenon, the physical processes underlying their formation and dismantling remain poorly understood, limiting insights into their role as coastal defense. This study fills a critical knowledge gap by analyzing the first long-term dataset that directly connects Posidonia oceanica seagrass berm dynamics to specific wave conditions. Measurements were collected at Cala Millor beach in Mallorca over almost a decade and the research utilized topo-bathymetric surveys, video monitoring, and wave measurements. Our research reveals that berm formation follows an annual cycle, driven by wave height, period, and direction, alongside seasonal availability of seagrass material. Numerical modeling further shows that high-energy waves facilitate berm formation, while low-energy, spilling waves contribute to their dismantling. These findings highlight the significance of wave conditions in berm dynamics, advancing our understanding of their potential role in coastal protection.

Analysis of Acoustic Surface Wave Focused Unidirectional Interdigital Transducers Using Coupling-of-Mode Theory

In cell or droplet separation, high acoustic wave energy of a surface acoustic wave (SAW) device is required to generate sufficient acoustic radiation force. In this paper, the electrode width-control floating electrode focused unidirectional interdigital transducer (EWC-FEFUDT) is proposed due to its enhanced focusing properties. The performance of the EWC-FEFUDT is investigated using the Coupling-of-Mode (COM) theory, and the COM parameter is extracted using the Finite Element Method (FEM). The four different forbidden band edge frequencies account for the unidirectionality of the proposed EWC-FEFUDT. A direction angle of ϕκ−ϕζ=44.5° of the EWC-FEFUDT (Design 3) is obtained, being fairly close to the optimum value of 45°. The EWC-FEFUDT (Design 3) has a lower insertion loss (IL) of −5.1 dB and greater unidirectionality (20 × log10(D) = 13.8 dB). The SAW maximum amplitude of the EWC-FEFUDT (Design 3) is increased by about 1.5×10−4 µm compared to that of the focused interdigital transducers (FIDTs). The maximum acoustic pressure of the EWC-FEFUDT is an order of magnitude higher than that of FIDTs. The EWC-FEFUDT exhibits enhanced focusing properties. The proposed EWC-FEFUDT may provide an alternative method for cell or droplet separation in an efficient manner.

Performance and mechanisms of a novel breakwater for protecting coastal box girder bridges from freak waves

Coastal bridges are vulnerable to extreme wave attacks, and the potential for damage from high-energy freak waves is increasing under climate changing scenarios. To mitigate the impact on these structures, a novel breakwater design is proposed, combining a floating structure anchored to a traditional submerged breakwater. Using a two-dimensional flume developed in OpenFOAM, simulations of freak waves and wave-structure interactions were conducted. The protective capabilities of the combined breakwater were assessed by analyzing the changes in force on the bridges, and the wave dissipation mechanisms were explored through wavelet transform results and flow field analysis. The study reveals that the combined breakwater effectively reduces wave loads compared to conventional submerged breakwaters, due to the conversion of high-frequency waves into low-frequency waves facilitated by the floating structure. This interaction, along with the submerged structure, enhances the overall stability and service life of the breakwater. The stability and load reduction performance are influenced by the initial draft and length-to-height ratio of the floating structure, with optimal performance achieved at specific configurations. The efficacy of the proposed breakwater is somewhat limited by long-period and highly nonlinear waves, while water depth has minimal impact. This combined breakwater design addresses the limitations of both submerged and floating breakwaters, offering valuable insights for the design of coastal bridge protection systems against freak waves.

New Material of Thylacocephala from the Early Ladinian (Middle Triassic) of Northern Grigna (Lecco, Lombardy, Northern Italy)

Here we report and describe a new assemblage of Thylacocephala (Crustacea) from the Early Ladinian Buchenstein Fm. (Middle Triassic) of Grigna, Northern Italy. The assemblage consists of at least four species from three different genera: Ankitokazocaris lariensis sp. n., Ankitokazocaris sp., Austriocaris sp., Stoppanicaris grignaensis gen. et sp. n. This thylacocephalan assemblage is rather diverse compared to the others of the Triassic. The largest size and ornamentation type of thylacocephalan species is compared among different periods of the Triassic and indicates that taxa with ridges on the carapace are generally smaller than those with smooth carapaces. This may be related to their different modes of life, such as inside or above the sediment with low oxygen levels. Large and smooth taxa were possibly more adapted to a life above sandy bottoms in shallow waters, under a somewhat high wave energy, while small, ornamented taxa are better suited for deeper environments with muddy bottoms, inside which they could move freely. The EDS analysis of Austriocaris sp. reveals that the cuticle mainly consists of apatite, which is in accordance with previous interpretations.

Silica nanofiber membrane with high reflectivity and low absorptivity for high-energy laser protection (29.0 kW/cm2)

To safeguard against high-energy continuous wave laser, the chosen strategy is a robust reflection to restrict heat generation instead of thermal protection. Based on this, the SiO2 nanofiber membranes (0.12 g/cm3) with nearly 100 % reflectivity and an extremely low absorption coefficient, were fabricated by electrospinning under the optimal parameters and calcinating at 600–1000 °C. The membranes, with a thickness of 4 mm, exhibit the best laser protection property reported to date. Under laser irradiation of 29.0 kW/cm2, they remain intact and achieve a steady state after 10 s with a rear temperature of only 700 °C because the necessary conditions for excellent laser protection property—the absence of highly absorbing groups, moderate fiber stacking density, presence of fiber stacking structure, chemical inertness, and specific thickness—are all met. In addition, excellent mechanical properties, including a tensile strength of 16.6 MPa (normalized value through equivalent solid materials for comparison purposes), a compressive strength of 0.07 MPa, and good bending performance, provide guarantees for their practical applications.

Controls on coastal bluff erosion of a drowned drumlin field: Boston Harbor, Massachusetts

Eroding coastal bluffs pose significant risks to coastal communities, and an improved understanding of their erosional processes and mechanisms is essential for developing effective management strategies. The Boston Harbor Islands comprise more than two dozen drowned drumlins that were formed during the late-Pleistocene, many of which are now connected by spits. Exposed bluffs on the islands experience erosion due to waves and precipitation and are increasingly threatened by accelerating sea-level rise (SLR). Retreat rates for 31 bluffs along the drumlin shore, derived from orthoimagery (1995–2021) using the Digital Shoreline Analysis System add-in for ArcMap 10.8, range from 0.0 m/yr to 1.5 m/yr. These rates were examined in relation to several factors, including shoreline orientation, significant wave height during extratropical storms, till matrix composition, base elevation, bluff height, and presence of engineering structures. Clusters of bluffs with similar characteristics were identified, suggesting that high retreat rates coincide with bluffs that experience high wave energy, face the northeast and have high sand-to-mud ratios. The complexity of the Boston Harbor drumlin field and the variability of individual factors controlling erosion highlights the impracticality of developing a universal statistical model for predicting erosion rates. Rather a more suitable approach involves assessing trends among clusters of bluffs with similar characteristics. A similar approach can be taken for exploring the variability in retreat rates along other coastlines with complex or irregular bluff systems and wave fields.

Investigating the evolution of sand bars and natural channel formation in the Mandovi estuary along the central west coast of India

Coastal formations, such as sandbars, play a vital role in shaping the environment and maintaining local and regional coastal morphology. This study deals with two noteworthy sandbars, namely Aguada and Reis Magos which are in the Mandovi estuary of the Goa region in the central west coast of India. They have attracted great attention because of their dynamics and their role in shaping the adjoining coast. This study employs a comprehensive approach, incorporating in-situ observations and remote sensing methods, to investigate the mechanisms underlying the emergence and dissipation of these sandbars and their linkage with adjoining navigational channels and coastline. During the intense wave conditions of the southwest monsoon (June to September), these sandbars undergo a temporary phase of dispersion. This phenomenon results in the accumulation of sand from both the sandbars and the neighbouring Miramar beach within the navigational channel. As a consequence, it obstructs maritime traffic and forms a unified shallow bar, obstructing maritime navigation in the area. However, following the attenuation of monsoon waves in October to November, the sandbar and beach initiate a gradual replenishment process, aimed at compensating for the sediment loss incurred during the monsoon season. This recurring trend has demonstrated persistent characteristics over an extended period. The presence of the sandbar may pose navigational challenges for large barges, cruise ships, and fishing boats but on the other hand, it serves as an effective barrier against incoming high-energy waves into the inner parts of the Mandovi estuary. Results revealed notable variations in the extent of the sandbar over the study period. The maximum recorded extent of the sandbar was 82.48 ha and 32.59 ha on May 04, 2021, while the minimum extent was measured at 36.68 ha and 7.14 ha on February 14, 2019, for Reis Magos and Aguada bar respectively. The sandbar promotes a calm environment along the shoreline and reduces erosion susceptibility by dissipating the wave energy before reaching the riverbanks. The absence of this protective sandbar would have significantly impacted the parts of the Goa region. Notably, the maximum erosion of 107 m was observed at the right bank of the estuary, while the maximum accretion of 141 m was recorded in the Caranzalem from 1975 to 2023. This study contributes valuable insights into the formation, dissipation, and environmental implications of sandbars within the estuary in Goa. The integration of in-situ observations and remote sensing data affords a comprehensive understanding of sandbar dynamics, highlighting the essential role that they play in coastal protection, navigation and the preservation of the local environment.

Spatial and temporal dynamics of groundwater biogeochemistry in the deep subsurface of a high-energy beach

Intertidal sandy beach systems are considered complex biogeochemical reactors. At beach sites that are subject to high tidal and wave energy, seawater circulation can reach tens of meters deep into the subsurface and changing environmental conditions are assumed to lead to dynamic groundwater flow paths, saltwater-freshwater mixing zones, and a spatio-temporally variable groundwater biogeochemistry. Previous studies mainly focused on the upper meters of subterranean estuaries (STE), while the deep subsurface remained a black box. This study presents spatial (cross-shore) and temporal (∼ six-weekly, over 1.5 years) dynamics of the groundwater biogeochemistry that were observed down to 24 m below the ground surface (mbgs) of a sandy high-energy beach on Spiekeroog Island (Germany).In addition to redox conditions along a cross-shore transect ranging from oxic to Fe oxide reducing/slightly sulfidic, we found a previously unknown, distinct vertical redox zonation as well. Temporal variations of the biogeochemistry within low salinity groundwater at the most landward station close to the dune base were mainly driven by storm flood related seawater infiltration. Around the high water line, the extent of the upper saline plume (USP) varied over time. Furthermore, temporal dynamics of the O2 saturation at 6 mbgs indicated a seasonally shifting depth of the oxycline at this location. In the lower intertidal zone, groundwater solute concentrations displayed a temporally variable zone of deep freshwater discharge.Regarding the impact of the deep STE on the groundwater biogeochemistry of the discharge zone, our data revealed that nutrient, Mn, and Fe release along the deep flow paths through the USP towards the discharge zone was limited, likely due decreasing availability of labile organic matter and subsequent slowing down of metabolic processes with depth. High concentrations of metabolites in the upper ∼ 2 mbgs of the discharge zone were, therefore, rather attributed to the incorporation of labile organic matter during continuous and storm flood related sediment relocation and/or the contribution of older waters, e.g., the subtidal saltwater wedge.

The impact of a storm on the microtidal flat in the Yellow River Delta

Strong hydrodynamic forces generated by storms are key in shaping coastal tidal flats. Most tidal flats achieve equilibrium by adapting to hydrodynamic conditions and sediment inputs. However, high-energy wave activity during storms disrupts this equilibrium, causing rapid and significant changes, particularly in tidal flats, especially in microtidal flats, which are characterized by low tidal ranges. In this study, we conducted an 11-d field campaign on a microtidal flat in the Yellow River Delta (YRD), capturing data during both stormy and calm weather conditions. We measured tidal currents, wave activity, suspended sediment concentrations and sediment grain sizes. The results demonstrated that the tidal flat maintained equilibrium under calm conditions, with minimal fluctuations in bed level (within ±2 mm). Contrastingly, severe erosion and sediment removal during the storm significantly altered the equilibrium of the area. The storm-induced high shear stresses, ranging from 1.02 to 1.48 N/m2, along with alongshore sediment transport, resulted in an elevation change of −10 mm. Furthermore, the subsequent bed level recovery was minimal and insufficient to offset the erosion. Compared to that of the mesotidal and macrotidal flats, post-storm recovery on microtidal flats was limited due to shorter inundation periods and weaker hydrodynamic forces. Therefore, frequent storms may lead to continuous shoreline retreat on microtidal coasts. Conclusively, the present findings underscore the significant impact of storm-induced erosion on the evolutionary processes of microtidal flats and suggest that greater attention should be given to protecting these areas during storms in the Yellow River Delta. The insights can guide the development of more effective coastal protection strategies, highlighting the need for enhanced measures to mitigate erosion and promote resilience in microtidal regions.

Longshore Sediment Transport Across a Tombolo Determined by Two Adjacent Circulation Cells

AbstractLongshore sediment transport (LST) is essential for shaping sandy shorelines. Many shorelines are complex and indented, containing headlands, offshore islands and tombolos. Tombolos often form between islands and the mainland; however, the conditions for LST across tombolos are unclear. This question is important because tombolos are often reinforced with anthropogenic infrastructure, potentially causing sediment starvation of downdrift beaches. Along many shorelines, the return to a tombolo's natural condition has been proposed to promote sediment connectivity and counteract erosion. Nevertheless, the implications of such restorations remain uncertain. In this study, we employ the Delft3D wave‐current model to investigate hydrodynamics and sediment dynamics across a tombolo, examining its role as a connector between adjacent beaches. Contrary to expectations, our simulations show only diminutive longshore currents from the updrift beach across the tombolo unless offshore wave heights exceed 8 m. Instead, predominant currents crossing the tombolo originate from offshore of the island, driven by storm‐induced water level differences and circulation cells on both sides of the tombolo. The offshore island shelters the downdrift domain, resulting in higher wave energy and dissipation updrift of the tombolo. Further, increasing wave height or wave approach angle not only intensifies water level differences but also relocates circulation cells, enhancing total sediment transport from the updrift beach across the tombolo. However, in general, the deposition of sediment from the updrift side of the domain does not compensate for the sediment loss on the downdrift beach. We conclude that LST across tombolos is limited and occurs only under extreme wave conditions.

Structural, electrical, and dynamic scaling behavior of Ba0.85Ca0.15Zr0.10Ti0.90O3 nanoceramics synthesized at low temperature by sonochemical method

In contrast to lead-based materials, lead-free ceramics Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) offer outstanding dielectric, ferroelectric, and piezoelectric properties. A novel sonochemical method is employed to synthesize BCZT at low temperatures. The impact of high-energy acoustic waves reduces the calcination temperature to 600 °C, which is 300–400 °C lower than the already reported values. The samples are further sintered at different temperatures. The BCZT shows good dielectric properties (εr ∼3000 and tanδ ∼0.075 at 1 kHz) at room temperature. X-ray diffraction analysis shows the co-existence of tetragonal and orthorhombic phases. Further, the scaling behavior is studied for domain dynamics in the sample. A three-stage polarization reversal mechanism is observed in BCZT ceramics. From the systematic study of the domain reversal mechanism, BCZT appears to be a promising candidate for sensors and actuator applications.

Individual-based numerical experiment to describe the distribution of floating kelp within the Southern Benguela Upwelling System

Abstract Kelps are resilient organisms, capable of thriving in high-energy wave environments. However, when hydrodynamic drag forces exerted by the wave environment exceed the kelps’ structural limits, individuals become dislodged. Floating kelps generally follow ocean currents, traveling long distances until air-filled structures fail or the epibiont load becomes too great, causing them to sink to the seafloor. The ability of kelp to disperse over vast offshore and nearshore systems makes them important for organic subsidy and as a dispersal vector for marine organisms. Previous research on dislodged macroalgae focused on context-specific rafts, limiting insights into the broader ecological role of floating kelp. This study employed a site-specific Lagrangian trajectory model to describe the spatial distribution of floating Ecklonia maxima along the South African coastline. The model incorporated buoyancy and sinking using site-specific morphological data. Findings revealed that the distribution of floating E. maxima is influenced by oceanographic conditions, and seasonal patterns were also evident. Mesoscale features played a vital role in kelp accumulation on the surface and seafloor and acted as barriers to dispersal. This study offers essential insights into kelp’s role as an organic subsidy and provides numerical evidence for kelp’s potential as a carbon sink, contributing to a better understanding of kelp ecosystems and their ecological functions.

Focused High-Energy Extracorporeal Shock Wave Therapy (ESWT) for Bone healing Disorders of the Forearm and the Hand

ESWT is a non-surgical treatment option but can also be used in addition to surgical treatment (stabilisation, freshening, defect filling, removal of discomforting osteosynthesis material) for the treatment of delayed bone healing (DBH) and non-union (NU). Its value as well as influencing factors on the upper extremity have not been adequately quantified so far. Sixty cases were retrospectively studied after application of focused high-energy ESWT with regard to healing rate and consolidation time. The influence of age, location, time of treatment and treatment prior to and concurrent with ESWT were analysed. In 70% of the cases, healing occurred after a median of 2.4 months (DBH) and 2.8 months (NU). The median age of healed (DBH 44 y., non-union 35 y.) and non-healed (DBH 51 y., NU 37 y.) did not differ significantly. The time between trauma/surgery and ESWT was 4.2 months for DBH in healed and 3.7 months in non-healed without a significant difference, and 27 months for NU in both healed and non-healed. Age and smoking status also had no influence. The healing rate was highest at metacarpal bone/finger/thumb (91%), followed by forearm shaft (88%), epiphysis/metaphysis of the forearm (67%), and, lastly, carpal bones (59%). After conservative pre-treatment, 55% healed, compared with 67% after more than two previous surgeries, 73% without any pre-treatment, and 75% after one previous surgery. Further analysis of surgical pre-treatment showed 85% healing after ORIF alone, 64% without previous surgery, and 57% healing after ORIF with bone grafting/debridement. Intraoperative ESWT combined with bone debridement/transplantation and ORIF resulted in 67% healing, compared with 86% in combination with ORIF alone. ESWT alone or with only minimal measures (removal of osteosynthesis material) led to 70% consolidation. ESWT is equally effective at any stage of a bone healing disorder. The principles of stability and filling of bone defects must also be taken into account when using ESWT; then ESWT alone or combined with surgery is equally effective. The negative influence of bone defects/resorption is still detectable even with ESWT. Furthermore, treatment of the scaphoid is more problematic compared with other locations. Previous surgery is not a negative factor, even with osteosynthesis material in situ.

A Novel Approach to Wave Energy Conversion Using CFD Technique

Abstract This article details the development and evaluation of a novel wave energy converter (WEC) aimed at efficiently capturing wave energy for electricity production. The study employs Computational Fluid Dynamics (CFD) techniques, specifically the URANS method and the k-ω SST turbulence model, to solve the Navier-Stokes equations and capture the free surface using the Volume of Fluid (VOF) model. The CFD results are validated against experimental data to ensure accuracy. Various design parameters of the proposed device were tested, revealing that the arms and bottom angle significantly affect its performance. Unlike the floating Wave Dragon (WD) device, which utilises potential energy and is set in deep water, the new fixed-seabed device is positioned in the transitional wave region near the shore, where waves retain 80% of their energy. It can be constructed from environmentally friendly cement, making it resistant to hurricanes and suitable for any wave turbine in the open sea. The MP687 turbine was used to capture the wave energy in the proposed device, testing its performance in three positions: in the open sea, in the middle of the device, and at the device’s outlet. The results show that the device significantly enhances wave energy concentration, especially when the turbine is placed at the outlet. The proposed device offers numerous advantages, including its fixed position in a high-energy wave zone, the efficient use of turbulent kinetic energy, and robust construction that can withstand storms.

Offshore wind and wave energy can reduce total installed capacity required in zero-emissions grids

As the world races to decarbonize power systems to mitigate climate change, the body of research analyzing paths to zero emissions electricity grids has substantially grown. Although studies typically include commercially available technologies, few of them consider offshore wind and wave energy as contenders in future zero-emissions grids. Here, we model with high geographic resolution both offshore wind and wave energy as independent technologies with the possibility of collocation in a power system capacity expansion model of the Western Interconnection with zero emissions by 2050. In this work, we identify cost targets for offshore wind and wave energy to become cost effective, calculate a 17% reduction in total installed capacity by 2050 when offshore wind and wave energy are fully deployed, and show how curtailment, generation, and transmission change as offshore wind and wave energy deployment increase.

Melatonin as a radioprotective agent against flattening filter and flattening filter-free beam in radiotherapy-induced lung tissue damage

Background Radiotherapy is a widely used treatment method in oncology, applied by delivering high-energy particles or waves to the tumor tissue. Although tumor cells are targeted with radiotherapy, it can cause acute or long-term damage to healthy tissues. Therefore, the preservation of healthy tissues has been an important subject of various scientific researches. Melatonin has been shown to have a radioprotective effect on many tissues and organs such as liver, parotid gland, brain, and testicles. This study aimed to evaluate the protective effect of melatonin against the radiation at various doses and rates administered to the lung tissue of healthy mice. Methods This study was a randomized case-control study conducted with 80 rats comprising 10 groups with eight animals per group. Of the 10 groups, first is the control group, which is not given any melatonin, and second is the group that does not receive RT, which is given only melatonin, and the other eight groups are RT groups, four with melatonin and four without melatonin. Results There was no statistical difference in terms of histopathological findings in the lung tissue between the second group, which did not receive radiotherapy and received only melatonin, and the control group. Lung damage due to radiotherapy was statistically significantly higher in the groups that did not receive melatonin compared to the groups that received melatonin. Conclusions This study revealed that melatonin has a protective effect against the cytotoxic damage of RT in rats receiving RT.

Enhancement of aluminum powder reaction behavior at high temperatures—Aluminum powders with “sea urchin structure” coated by AP

To solve the problem of high ignition temperature of aluminum powder and easy to burn into blocks at high temperatures, “sea-urchin-structured” aluminum powders (μAl@nAl) obtained by electro-explosion were coated by ammonium perchlorate (AP) on its surface. AP in a high-temperature environment has a rapid decomposition, then the gas production will promote the dispersion of aluminum powder into micro-clusters, thus preventing the aluminum powder agglomeration during the combustion process. The micro-nano composite aluminum powder (μAl@8 %nAl) and physical mixed aluminum powder (μAl + 8 %nAl) coated by AP were completed by solvent volatilization method. The coating surface was observed by scanning electron microscopy. The heat of combustion and pressure curves for different AP contents were tested using a chamber with a constant volume, and the ignition and combustion performance of the AP samples were investigated using a carbon dioxide (CO2) laser ignition device. The AP samples shortened the ignition delay time and improved the combustion performance in the fixed-volume combustion and laser ignition tests. Under atmospheric air, taking into account the theoretical calorific value, pressure curve, and combustion performance, the optimal AP content is 10 %. The thermal decomposition process of two samples was further analyzed using the thermogravimetric and differential scanning calorimetry (TG-DSC) method. The decomposition of AP advanced the first oxidation peak of aluminum powder; however, in the second step oxidation peak, the peak temperature of μAl@8 %nAl@10 %AP sample was delayed compared to μAl + 8 %nAl@10 %AP sample. High-voltage electrical explosions and high-energy laser-induced air shock waves were created to simulate the high-temperature environment of the detonation reaction zone, and pictures of the reaction process and pressure change curves of the “sea urchin structure” aluminum powder coated by AP at high temperatures were recorded. The results showed that the “sea urchin structure” aluminum powder coated by AP exhibited better combustion performance, and the reaction degree of the aluminum powder had been deepened.

The future of the Portuguese (SW Europe) most vulnerable coastal areas under climate change – Part II: Future extreme coastal flooding from downscaled bias corrected wave climate projections

Episodic extreme coastal flooding is considered one of the most serious threats to the global coastlines, endangering infrastructure, ecosystems, and communities. The synchronized effects of extreme wave events, storm surges and astronomical tides are particularly worrying in the context of sea level rise (SLR), and a comprehensive understanding of their future dynamics remains challenging. In this study, an innovative approach for a vulnerability assessment of sandy low-lying coastal areas, based on dynamic ensemble projections is proposed. In the current Part II study, the combined effects of future projected SLR, tides, storm surges and wave action are investigated at five key-locations along the Portuguese coastline, considering projected digital terrain models, built upon the shoreline projections obtained in Part I. Future extreme total water levels are obtained through a probabilistic approach, and extreme wave events are defined considering high wave energy thresholds in a changing climate. Overall, extreme coastal flooding is projected across several urbanized sections along the Portuguese coastline, especially in areas without artificial protection infrastructures. Dune erosion is expected along the sandy stretches, reducing the natural protection against extreme coastal events up to 13.3%, and promoting widespread overtopping, leaving populations more exposed. Future projections reveal the episodic flooding of up to 1.47 km2 of land along the 14 km of analyzed coastline, threatening households and commercial hubs, besides services and communication routes. As physical and human losses may increase substantially in the future, our results call for the implementation of adequate coastal management and adaptation plans, strategically defined to withstand changes until 2100 and beyond.

PENGARUH TAMBAK SILVOFISHERY TERHADAP SIFAT FISIK TANAH MANGROVE SEBAGAI LAHAN KONSERVASI DAERAH MUARA SUNGAI BOGOWONTO KULON PROGO DAERAH ISTIMEWA YOGYAKARTA

The Bogowonto River estuary is a coastal area in the open water category because it faces the Indian Ocean directly, it has high wave energy, which will cause erosion and abrasion, and the presence of mangrove and pond ecosystems (silvofishery) can support the development of coastal areas as conservation land. So it is necessary to conduct research to examine the influence of soil physical properties on silvofishing and determine the types of mangroves in the Bogowonto River estuary area. The method used was a survey, where soil samples were tested at the Yogyakarta BPTP Laboratory and the Yogyakarta "Veteran" National Development University at a depth of 0–20 cm and 20–40 cm. Sampling was conducted in a zigzag method from the left (near the pond) and right sides of the river. The results of the research found that there are 2 types of mangroves, namely the Tan cang (Bruguiera sp.), which grows far from the coastline and close to fish pond areas (silvofishery), has a has a relatively stable pH, is dominated by clay texture, and has a low salinity level. White Mangrove (Avicennia sp.) grows near the coastline, with a dominant sandy loam texture, low-normal pH, and high salinity levels. Mangroves that grow along the southern river in the presence of silvofishery can help with the deposition process of mud that is transported along the river and maintain the sustainability of fish populations, and litter from mangroves tends to increase the organic matter content of the soil.

The potential of Wave Energy Converters in the Galapagos islands

This study investigates the potential of Wave Energy Converters (WECs) technology in the Galapagos Islands. Despite the region’s high wave energy potential (262 TWh/year of gross potential and 25TWh/year of sustainable potential), the current high cost of WEC technology limits its economic competitiveness compared to mature renewables like solar and wind. Our analysis, using the OSeMOSYS model, reveals that decarbonizing the Galapagos’ power sector with solar and wind is feasible and cost-effective. However, deploying WECs is even more expensive. Initially, WECs have the highest levelized cost of electricity (LCOE) (43 ct.USD/kWh in 2030), but this decreases by 2050, ending up at 26 ct.USD/kWh, a value below the benchmark for fossil thermal power plants without fuel subsidies. Deploying WECs, together with solar and wind technologies may contribute for diversifying the Galapagos’ power system, reducing fossil fuel reliance, and mitigating climate change impacts.