Coastal Protection Research Articles

Enhancing Hydrodynamic Performance of Floating Breakwaters Using Wing Plates

Understanding the dynamic response of floating breakwaters to wave forces is essential for optimizing their design and improving coastal protection. The response amplitude operator serves as a key parameter in accurately predicting the structural response amplitudes at different frequencies and wave angles. By incorporating this knowledge, adjustments can be made to enhance the effectiveness of floating breakwaters. In this study, a comprehensive 3D model of the mooring system is developed to simulate its behavior under various wave and current conditions. The model takes into account critical design factors such as pontoon shapes, anchor types, placements, and configurations. Through simulations, valuable insights are obtained regarding the performance of the wing-plate floating breakwater mooring system across different operational settings. These findings contribute to the optimization of floating breakwaters and their ability to protect coastlines from wave impacts.

Whole-Genome Sequencing of Two Potentially Allelopathic Strains of Bacillus from the Roots of C. equisetifolia and Identification of Genes Related to Synthesis of Secondary Metabolites.

The coastal Casuarina equisetifolia is the most common tree species in Hainan's coastal protection forests. Sequencing the genomes of its allelopathic endophytes can allow the protective effects of these bacteria to be effectively implemented in protected forests. The goal of this study was to sequence the whole genomes of the endophytes Bacillus amyloliquefaciens and Bacillus aryabhattai isolated from C. equisetifolia root tissues. The results showed that the genome sizes of B. amyloliquefaciens and B. aryabhattai were 3.854 Mb and 5.508 Mb, respectively. The two strains shared 2514 common gene families while having 1055 and 2406 distinct gene families, respectively. The two strains had 283 and 298 allelochemical synthesis-associated genes, respectively, 255 of which were shared by both strains and 28 and 43 of which were unique to each strain, respectively. The genes were putatively involved in 11 functional pathways, including secondary metabolite biosynthesis, terpene carbon skeleton biosynthesis, biosynthesis of ubiquinone and other terpene quinones, tropane/piperidine and piperidine alkaloids biosynthesis, and phenylpropanoid biosynthesis. NQO1 and entC are known to be involved in the biosynthesis of ubiquinone and other terpenoid quinones, and rfbC/rmlC, rfbA/rmlA/rffH, and rfbB/rmlB/rffG are involved in the biosynthesis of polyketide glycan units. Among the B. aryabhattai-specific allelochemical synthesis-related genes, STE24 is involved in terpene carbon skeleton production, atzF and gdhA in arginine biosynthesis, and TYR in isoquinoline alkaloid biosynthesis. B. amyloliquefaciens and B. aryabhattai share the genes aspB, yhdR, trpA, trpB, and GGPS, which are known to be involved in the synthesis of carotenoids, indole, momilactones, and other allelochemicals. Additionally, these bacteria are involved in allelochemical synthesis via routes such as polyketide sugar unit biosynthesis and isoquinoline alkaloid biosynthesis. This study sheds light on the genetic basis of allelopathy in Bacillus strains associated with C. equisetifolia, highlighting the possible use of these bacteria in sustainable agricultural strategies for weed management and crop protection.

THE GROWTH OF ILLEGAL CONSTRUCTION IN THE COASTAL PROTECTIVE STRIPS OF THE STRYI RIVER BASIN

Currently, there is of today, there is practically no information about the current state and land use of coastal protection strips (CPS) and water protection zones in the Stryi river basin. This creates many misunderstandings and abuses during their use and leads to intensive degradation of the ecosystem of both this and other rivers of the Dniester basin into which it flows. Using the Google Earth Pro program, an assessment of the CPS structure in the Stryi River basin was carried out by comparing space images for the past 14 years. The analysis showed that illegal construction within the CPS of the river began after 2009, which creates the danger of possible inundation during floods and the development of erosion processes. This is also a threat to the hydroecosystem of the Stryi River, due to the settlement load on the floodplain, as well as non-compliance with sanitary standards and clogging with household waste.

Seagrass as a nature-based solution for coastal protection

Our coasts are facing a growing threat from rising sea levels and detrimental storm events. Nature-based solutions are gaining interest for their potential to provide multiple ecosystem services, including coastal protection. Seagrass can influence coastal sediment transport and wave propagation, however, whether seagrass can be used as an effective intervention for coastal protection is unclear. Using the Delft3D model, this study looks at how seagrass affects coastal hydrodynamics in a macrotidal bay, under idealised scenarios that simulate a rise in sea level and storm wave heights, emulating projected sea conditions under climate change. Through the use of a habitat suitability model, a seagrass patch in Morecambe Bay was simulated, based on a location within the bay that is most suitable for seagrass species Zostera marina. Hydrodynamic simulations were run for a number of scenarios for a domain with and without a seagrass patch. Scenarios included variable boundary wave heights, sea levels and vegetation parameters, to test the influence of seagrass in future climates. Results show that there is a reduction in mean and maximum wave height inside and behind the seagrass patch, with the largest changes in wave dissipation observed during higher boundary wave conditions. In these conditions the maximum wave height reduced by over a half within the patch. Simulations examining the influence of seagrass density and canopy height found that a lower density seagrass patch reduced maximum wave height more substantially than higher density patches. Although alternative hard engineered solutions are able to attenuate wave energy more effectively than seagrass, these results demonstrate seagrass could play an important role in conjunction with salt marsh restoration or existing hard engineering solutions, helping to mitigate the risk of flooding and erosion, whilst providing additional ecosystem services such as carbon sequestration and habitat provision.

Experimental investigation on attenuating wave run-up by emergent length and submerged length of rigid vegetation on a composite breakwater

Coastal vegetation not only provides efficient wave attenuation, but also serves to protect and restore the ecological environment, making it a favorable coastal protection measure. Composite breakwaters are a traditional engineering measure with good wave absorption performance. Accordingly, a plant-ecological composite breakwater is proposed. The effects of changes in the emergent and submerged lengths of rigid vegetation on the attenuation of wave run-up on the composite breakwater were investigated using experimental measurements. Cylinders were used to simulate vegetation in the experiment, neglecting their vibration. The results indicate that vegetation can effectively attenuate wave run-up. At larger wave heights, the maximum wave run-up is more sensitive to the submerged length of vegetation, with an attenuation rate of up to 44.6%. At smaller wave heights, the maximum wave run-up is more sensitive to the emergent length of vegetation, with an attenuation rate of up to 23.6%, which decreases with increasing wave period. Furthermore, there are systematic changes in the overall wave run-up trend occur over time for different conditions.

Racial hydrologies

AbstractIn the South Carolina Lowcountry, near‐annual hurricanes and record‐breaking sea levels have led to disastrous flooding, overwhelming the region's historical tidal infrastructures and entrenched racial geographies. In response, Lowcountry governments, institutions, and residents have undertaken efforts at “perimeter protection,” raising dikes and seawalls to safeguard selected urban and rural plantation spaces from tidal flooding. Although perimeter protection is presented as a neutral resilience strategy, its practices and material forms reveal a close relationship between coastal protection and efforts to preserve landscapes of white supremacy. Such logics of perimeter protection contrast with everyday affective encounters with eroding coastlines and with the futures outside of bounded edges imagined by Black Charlestonians. By situating the region's hydrological history within the legacy of slavery and plantation extraction, and by following the effects of current sea level rise, we can see how historical hydrologies—which in this case are also racial hydrologies—are entangled with landscapes of contemporary environmental injustice.

Experimental study on wave attenuation and beach profile evolution under the protection of submerged flexible vegetation

Coastal protection methods are evolving from hard engineering techniques to natural enhancement approaches. Aquatic vegetation provides an environmentally friendly solution by effectively dissipating waves and resisting erosion. Laboratory flume experiments were conducted to investigate the effect of submerged flexible vegetation on the regular wave attenuation and cross-shore profiles on the artificial plane beach under varying hydraulic conditions. Variations in the waveform, wave spectrum, and wave height were analysed in the vegetation zone. Results show vegetation distorts the waveform and accelerates the attenuation process of the wave energy, and wave height evolution behaves differently from the theoretically obtained attenuation by Mendez and Losada (2004) due to the underestimating vegetation-induced attenuation and neglecting sediment-induced attenuation. Additionally, the formation process of the winter and summer profiles of the vegetated beach was analysed by the screenshots. Regenerated wave breaking becomes more apparent with increasing wave periods. The critical surf similarity parameter of the vegetated beaches was found to be lower than that of a smooth, impermeable slope because of the energy dissipation. Vegetation did not alter the type of the beach profiles, as compared to the final profiles and their characteristic parameters of the unvegetated beaches. Instead, it reduced the erosion depth and brought the eroded area closer to the shoreline. Dimensionless parameters were formulated to characterize the response of the cross-shore beach profile under the shelter of flexible vegetation, and an empirical equation about maximum erosion depth was developed within the scope of the experiment.

Systematic Literature Review on Smoothed Particle Hydrodynamic Method for Coastal Protection Optimizing

Systematic Literature Review on Smoothed Particle Hydrodynamic Method for Coastal Protection Optimizing

Coastal resilience and shoreline dynamics: assessing the impact of a hybrid beach restoration strategy in Puducherry, India

Puducherry, a Union Territory of India, has been strongly affected by severe erosion after the construction of the Puducherry port in 1989. To mitigate this cause, the National Institute of Ocean Technology, Chennai, and the Puducherry government implemented a beach restoration strategy involving a hybrid solution in 2017 for coastal protection/stabilization and the restoration of the lost beach. The strategy involved deploying a steel reef into the nearshore sea and implementing beach nourishment processes. To monitor the coastal morphological changes after implementing the coastal protection strategy, the Digital Shoreline Analysis System, was adopted to calculate the rate of shoreline change statistics for the years 2016 to 2022. It uses spatio-temporal shoreline positions from multi-temporal satellite imagery. The shorelines are extracted from the Sentinel-2A satellite images by a Normalized Differential Water Index based semi-automated model. Statistical parameters in DSAS analyze the shorelines to determine the shoreline changes in this area. The results reveal the remarkable resilience of a newly restored beach, where the linear regression rate statistics in Zone A show an average accretional rate of 2.92m/yr. Alternatively, Zone B exhibits an average erosion rate of -0.23m/yr, with intermittent sandy beaches experiencing maximum erosion rates of -1.63m/yr. The influence of longshore current direction and sediment transport on shoreline movement is evident in seasonal analysis, with shoreline development and recession primarily observed near shore protection structures. The study’s outcome provides valuable insights for coastal management, offering a reliable approach for shoreline monitoring post-implementation of mitigation projects.

Ecological Impacts of Coastal Protection on the Vegetation of Sandy Coasts at the German Baltic Sea Coast

Sand nourishments and groynes as coastal protection measures (CPM) address similar challenges on sandy coasts but take different approaches: while groynes are intended to reduce alongshore sediment transport and erosion, nourishments add new sediment to the system to compensate for erosion. The aim of this study is to compare the ecological effects of such measures on the vegetation. To this end, nutrient analysis and botanical mappings were carried out on a site with installed groynes, a site where sand nourishments are regularly carried out, and a control site without any CPM. In addition to an increase in nutrient availability after the sand nourishment, significant changes in plant species diversity and composition were also measured. The number of higher plants, mosses, and lichen species was lower at the nourishment site. The opposite impacts were observed at the groyne site: an increase in sediment cover by higher plants and mosses and a distinct increase in lichen species. The results suggest that groynes lead to a stabilization of the coastal system and enable dense vegetation growth. In contrast, sand nourishments lead to nutrient input and unstable habitat conditions, attracting certain plant communities but preventing the establishment of ground-covering vegetation.

Environmental risk assessment of coastal dredging based on clustering of meteocean forcing

Dredging and dumping in-situ sediments is a fundamental operation for most coastal engineering projects and coastal defense projects, such as the construction of breakwaters, beach nourishment and land reclamation. Future projections in terms of coastal hazard suggest that coastal protection and land reclamation project will be more and more frequent. In this context, the assessment of the environmental and socio-economic impact of the risk induced by dredging is a fundamental step during both the design stage and the operational management. Most of the standard practices and available risk assessment frameworks rely on the numerical prediction of the sediment plume in the large field driven by coastal circulations forced by tides, winds and waves. In this study, we formulated a new risk assessment framework based on an unsupervised machine learning clustering algorithm, K-means clustering, for generating representative meteocean scenarios subsequently used to force a regional circulation model. Moreover, we introduced three criteria of hazard/risk based on the spatial and temporal evolution of the suspended sediment concentration that explained different environmental impacts and two new methods to synthetically present the risk values. The major improvement of the present framework is that the final probability of risk fully describes the statistics in terms of hydrodynamic and dredging conditions.This framework presents the probability analysis of risk spatial distribution based on representative hydrodynamic conditions and dredging scenarios, which is a major improvement of this study compared with previous risk assessment strategies that were unable to predict quantified dredging risk before field construction. Finally, to demonstrate the potentiality of the risk assessment framework, we applied this methodology to the Hong Kong Water and Pearl River Estuary (China) as a pilot case.

Evaluasi Bangunan Pelindung Pantai Sisi Miring Dalam Upaya Penanggulangan Abrasi Pesisir Pantai

The coast of Kampung Jawa Lama, Banda Sakti Sub-district, Lhokseumawe City is a fishing area and densely populated. The breakwater building in the coastal area of Kampung Jawa Lama is a sloping Breakwater with a height of 1.5 m and a width of 1 m. The type of breakwater used is usually determinet by the availability of material on the site. The problem in this research was the cause of abrasion and its impact, as well as how to plant coastal protection structures. The purpose of this study was to reduce the impact of erosion, abrasion and damage to the buildings and to re-evaluate coastal structures. The method used on this research is Hudson method and descriptive analysis by making direct observation and reviuwing research that has been done previously. The cause of abrasion is triggered by several factors such us tides, high sea waves and ocean currents that have the potential to cause damage as a result of strong winds that produce destructive waves. The community also receiver the impact of the abrasion, namely decreasing income, the place where they live is inundated by sea water and it affects the decline in the quality of life of the community. One of the efforts that can be applied to reduce the abrasion problem in the area is to build a Breakwater construction. Based on calculation, the results obtained in the planning reviuw of the existing shoreline protection building were 1.5 m, so that to prevent abrasion the increase in height of the building 4.074 m was 5.574 m with a peak width of 1 m so that increase of 0.20 m was 1.2 m, the thickness of the first layer of protection was 1.2 m and the thickness of the second layer was 0.60 m. The width of the leg guard is 1.8 m with a thickness of 0.5 m

Evaluation of the Factors Affecting the Hydraulic Stability of Tblock™ Coastal Protection Armour Unit

Evaluation of the Factors Affecting the Hydraulic Stability of Tblock™ Coastal Protection Armour Unit

The effectiveness of mangrove forests as a nature-based solution against flood risk under an extreme weather event

It is becoming increasingly urgent to respond to coastal hazards as the intensity of tropical cyclones exacerbates flood hazards. Over the last few decades, both the number and severity of hazards have significantly increased. Coastal area growth has eroded the protective benefits provided by natural regions such as mangroves and other coastal wetlands. Such habitats can reduce flood damage through coastal protection processes and despite their importance, there is currently no estimate of the impact mangrove forest characteristics have on the rate of flood risk reduction. This study addresses this gap by developing a numerical model for evaluating the coastal hazard risk reduction provided by potential mangroves in coastal areas. Gonu tropical cyclone (2007) is considered in this paper for the assessment over the Port of Sur, Sultanate of Oman. Several synthetic land covers were developed in the study area by modifying Manning’s coefficient. To do this, MIKE 21 model was used to predict flood characteristics and the results are calibrated by observation data. After the implementation of various land cover scenarios into the model, a reduction of up to 49 % in flow velocity and 17.9 % in inundation depth were found. Furthermore, flow velocity and inundation depth both vary with the change in characteristics of mangrove forests. The results give valuable information for the nature-based disaster risk reduction approach.

Wastewater Management Strategy for Resilient Cities—Case Study: Challenges and Opportunities for Planning a Sustainable Timor-Leste

High population growth, a lack of wastewater treatment plants and poor wastewater management are major challenges in wastewater management in Timor-Leste (East Timor). One of the approaches of the government of Timor-Leste is to separate wastewater into greywater and blackwater from domestic, commercial, residential, and industrial areas. Three methods were applied to obtain insight into the locations and discharge of grey- and blackwater to develop a cost-effective wastewater strategy: a field survey and data collection, interviews with over 130 participants from local authorities and communities, and the open-source mapping of locations of wastewater discharge. This research concluded that 47.7% of the grey wastewater is discharged into open sewers connected directly to the sea. Most communities discharge their wastewater directly due to the absence of wastewater management, policies and regulations, and lack of communities’ understanding of the possible health impacts of wastewater. The impact of poor wastewater management showed that most of the children in these communities have suffered from diarrhea (73.8%), and in the rainy season, there is a high possibility of infection with waterborne diseases. The literature review, field mapping, and interviews show that there is high demand for a cost-effective wastewater strategy for health improvement. Low-cost nature-based solutions such as constructed wetlands and bioswales can be implemented with local skills and materials to improve the wastewater situation and address other challenges such as biodiversity loss, heat stress, drought, and floodings. These installations are easier to rebuild than large-scale grey infrastructure given the multiple hazards that occur in Timor-Leste: landslides, earthquakes, strong wind, and pluvial and fluvial floodings, and they can serve as coastal protection.

Trend of harmful algal bloom dynamics from GOCI observed diurnal variation of chlorophyll a off Southeast coast of China

Timely and accurate observations of harmful algal blooms dynamics help to coordinate coastal protection and reduce the damage in advance. To date, predicting changes in the spatial distribution of algal blooms has been challenging due to the lack of suitable tools. The paper proposes that the development and disappearance of algal bloom can be monitored by satellite remote sensing in a large area from the diurnal variation of chlorophyll a. In this paper, 32 pairs of observed data in 2011–2020 showed that it was most appropriate to outline the areas where the diurnal variation (the standard deviation calculated from the daily chlorophyll a) in chlorophyll a was more than 2.2 mg/m3. Among them, 30 pairs of data showed that the high chlorophyll a diurnal variation could predict the growth of the algal bloom in the next days. In these events, the median area difference between the two spatial distributions was -0.08%. When there was a high diurnal variation in chlorophyll a in the area adjacent to where algal bloom was occurred, a new algal bloom region was likely to spread in subsequent days. Continuous multiday time series showed that the diurnal variation in chlorophyll a can reflect the algal bloom’s overall growth condition.

Application of ramie-based eco-friendly material in coastal protection structures in Indonesia: feasibility study focusing on strength and biodegradability

ABSTRACT Coastal erosion presents a significant environmental threat globally, including in the Northern Java coastal area of Indonesia. As employing hard structures is not an environmentally sustainable practice, nature-based solutions, such as mangrove forests, have emerged as a global trend offering sustainable coastal protection. However, safeguarding young seedlings from wave and current forces remains challenging. Given that temporary structures, such as synthetic geo-bag dikes, considered for protection pose environmental challenges as they degrade slowly, the use of natural fibres such as ramie, unique to Indonesia as a strategic raw commodity, is a sustainable alternative. The study examined ramie fibres (0.28 mm thick) as an eco-friendly geo-bag material through laboratory tests, biodegradability burial tests, and comparisons with other natural fibres. Despite alkali treatment, the strength of ramie fibre did not meet standard geotextile parameters, and its degradability rendered it unsuitable for the expected service life. Ramie would need specific treatments to become a viable alternative for geo-bags. In conclusion, further research is needed to explore how ramie can serve as a sustainable geo-bag material.

REDESIGN SHORE PROTECTION KAWASAN INDUSTRI KENDAL (KIK)

Abrasion incidents on the coastline in the KIK area continue to occur and cause the area boundaries to decline. so that appropriate coastal protection structures are needed. The aim of this research is to carry out re-planning in the Kendal Industrial Area (KIK) in the future area boundary plan. In carrying out this research, daily wind data for the period 2017 - 2023 is needed from a nearby location, namely the Tanjung Emas Maritime Meteorological Station, Semarang. The analysis carried out includes fetch, windrose, wave calculations, building design and force calculations in shore protection construction. From the results of the windrose analysis, the dominant wave direction is northwest. Analysis of waves in the deep sea obtained a height value of 2.45 m and a wave period of 8.32 sec. Based on the calculation results, breaking waves will occur at a depth of 2.02 m. Because the building location is at a depth of 2m, where breaking waves occur, the breaking wave height is used in building planning. The coastal protection building chosen is shore protection construction or a tetrapod sea wall. Peak elevation of 4.76 meters, peak width of 3.55 meters, building base length of 22.45 meters, back slope of 1:1, arm slope of 1:2, the first type of protective layer material uses tetrapods, second and third layer using split stone pairs with 2 size combinations.

Experimental study on the use of artificial meadows that mimic wave-vegetation interactions for coastal protection

A detailed experimental study was conducted on five artificial meadows made of structures that mimic wave-vegetation interactions. The meadows were of different lengths and leaf thicknesses under regular and random waves, such that the leaf thickness changed as the meadow length increased. Different wave heights, periods, and tidal conditions were examined. The results for regular and random waves were consistent. The meadow length had a stronger influence (30%–50%) on wave transmission than leaf thickness (5%–10%). A lower wave transmission was observed at higher wave energies due to enhanced wave-vegetation interaction, higher wave reflection, and effective energy dissipation. Compared with submerged conditions or when the top of the meadow was at still-water level, a lower wave transmission and higher wave reflection and energy dissipation were noted when the leaves emerged in the air. The longest meadow in the emerged condition reduced the wave height by more than 50% at mid meadow. Furthermore, a wave transmission coefficient of 0.3 was achieved by this model, which is desirable for the design of this wave barrier type. The model with the best overall hydrodynamic performance can be used alone or combined with existing natural vegetation for coastal protection.

Hydrodynamic Assessment of A New Nature-Based Armour Unit on Rubble Mound Breakwater for Coastal Protection

Hydrodynamic Assessment of A New Nature-Based Armour Unit on Rubble Mound Breakwater for Coastal Protection