Shoreline Protection Research Articles

Innovative Coastal Resilience: Design and Application of Hydraulic Geotextile Tubes as Sustainable Breakwater Cores in La Union

The constant assault of waves contributes to the loss of valuable coastal land of La Union, necessitating innovative and sustainable methods to protect the shoreline. In the pursuit of sustainable solutions, innovative technologies such as hydraulic geotextile tubes have emerged as promising contenders for enhancing shoreline protection. This study explores the design and application of hydraulic geotextile tubes as breakwater cores along the La Union shoreline. Due to their permeability and flexibility, hydraulic geotextile tubes offer a viable substitute for conventional breakwater materials. The research aims to provide valuable insights into sustainable coastal management by determining how these tubes can be designed to resist wave forces, ensure stability against hydrodynamic pressures, identify various installation methods, and evaluate their advantages and disadvantages in preventing shoreline erosion and potentially reclaiming sand. The study's findings could inform strategies that balance shoreline protection with environmental preservation. It highlights the interaction between creative engineering solutions and environmental stewardship in addressing evolving coastal challenges.

Nature‐based shoreline protection in newly formed tidal marshes is controlled by tidal inundation and sedimentation rate

AbstractMany tidal marshes have been lost by past land use changes, but are nowadays increasingly restored and created to provide valuable ecosystem services such as nature‐based flood and erosion protection along estuarine shorelines. To be functional for flood and shoreline erosion protection, restored and created tidal marshes should develop erosion resistant sediment beds. Here, we investigated which factors drive the spatial variations in sediment strength and erosion resistance in a developing tidal marsh restoration site. Our results show that decreasing tidal inundation frequency, decreasing sedimentation rate, and better drainage led to stronger consolidation in deeper sediment layers. This consolidation resulted in greater sediment strength, quantified here by shear strength and penetration resistance. Generally, sediment strength was greater when sediment had higher bulk density, while a higher water and fine fraction (= clay and silt) content decreased sediment strength. Overall, all measurement locations were relatively erosion resistant, likely caused by the dense root network and cohesive sediment. To restore or create resilient tidal marshes for nature‐based flood and shoreline erosion protection, we should thus aim for sites with relatively low tidal inundation frequency, moderate sedimentation rates, and cohesive sediment mixtures of clay, silt, and sand, which are well drained and have potential for vegetation establishment. These conditions have a high likelihood of resulting in restored or created tidal marshes that contribute to nature‐based flood and shoreline erosion protection.

Environment and Socio-Economic Impact of Mangroves at Mobil, Dunggoan, Danao City, Cebu, Philippines

This study explored the environmental and socio-economic impacts of the mangrove rehabilitation project in Mobil, Dunggoan, Danao City, Cebu. It examined the demographic profile of residents, their perceptions and contributions to the project, and the effectiveness of project monitoring. In addition, the researchers conducted an actual measurement of the height and spread branches of the planted mangroves. The research employed descriptive method, utilizing surveys and direct measurements to assess the survival rate and growth of mangroves, as well as the distribution of marine life using quadrat method. Findings indicate a significant survival rate of mangroves, with Rhizophora stylosa and Rhizophora apiculata being the predominant species. The project has notably enhanced shoreline protection, erosion prevention, aquatic habitat, water quality, and the aesthetic appeal of the cove. The study underscored the necessity of implementing stricter monitoring, waste management, restoration projects, and community awareness programs to improve mangrove rehabilitation.

Oyster Restoration to Recover Ecosystem Services.

Oyster reef loss represents one of the most dramatic declines of a foundation species worldwide. Oysters provide valuable ecosystem services (ES), including habitat provisioning, water filtration, and shoreline protection. Since the 1990s, a global community of science and practice has organized around oyster restoration with the goal of restoring these valuable services. We highlight ES-based approaches throughout the restoration process, consider applications of emerging technologies, and review knowledge gaps about the life histories and ES provisioning of underrepresented species. Climate change will increasingly affect oyster populations, and we assess how restoration practices can adapt to these changes. Considering ES throughout the restoration process supports adaptive management. For a rapidly growing restoration practice, we highlight the importance of early community engagement, long-term monitoring, and adapting actions to local conditions to achieve desired outcomes.

Urban oasis? Abundant dice snake (Natrix tessellata) populations along artificial lakeside habitats in urban landscapes

ContextHuman-induced landscape modification, such as urbanization, creates new environments that can have adverse effects on flora and fauna, posing threats to biodiversity. Understanding how reptiles respond to urbanization is crucial, especially in light of their ongoing population declines.ObjectivesWe examined the influence of landscape-scale and local-scale urbanization features on the abundance of an aquatic snake species. Our investigation focused on dice snakes (Natrix tessellata) inhabiting a lake with a heavily urbanized shoreline.MethodsWe conducted visual encounter surveys at 25 study sites during the activity period of dice snakes around Lake Balaton in Hungary. We measured both landscape-scale and local-scale variables, including urban land use cover, vegetation cover, road cover, distance of main roads and city size, emergent vegetation cover and the area of artificial rock and concrete shoreline protection structures. We analysed snake survey data using N-mixture models to estimate abundance and examine relationships with landscape-scale and local-scale variables.ResultsUrban land use cover, road cover, the proximity of main roads and the extent of artificial rock and concrete shoreline protection structures positively affected the abundance of snakes. These findings imply that urban habitats may offer new ecological opportunities for dice snakes.ConclusionsThe findings of this study indicate that both landscape-scale and local-scale human-induced landscape modifications may have a positive impact on the abundance of urban snakes. Taken together, our findings suggest that urbanization is a complex phenomenon, affecting species at different levels and with subtle effects.

Experimental study on the hydrodynamic performance of a multi-DOF WEC-type floating breakwater

A hybrid system consisting of wave energy converters and breakwaters can be applied for both wave energy conversion and shoreline protection. Besides, the cost of wave energy conversion is believed to be reduced by such a combination. In this paper, a two-dimensional asymmetric wave energy converter-type breakwater with a triangle-baffle bottom that can convert wave energy through its heave motion is proposed and investigated experimentally in regular waves. A supporting system is designed and established to allow the model to move in a single degree of freedom or prescribed combination of multiple-degree-of-freedoms. The effects of the geometric asymmetry, the bottom slope, the width-to-draft ratio, and the multiple-degree-of-freedom motion on the wave energy conversion and attenuation performances are analyzed. The results show that the triangle-baffle wave energy converter-type breakwater has much higher wave energy conversion efficiency than its rectangular counterpart with the same displacement. Increasing the bottom slope and allowing pitch motion can improve efficiency, allowing surge motion will reduce efficiency, and the effect of increasing the width is uncertain due to two conflicting effects. The asymmetry, bottom slope, and width only have a limited influence on the wave attenuation, whereas surge and pitch motions reduce the wave attenuation in short waves, analogizing a wavemaker.

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

A multi-faceted methodology for calibration of coastal vegetation drag coefficient

The accurate prediction of wave height attenuation due to vegetation is crucial for designing effective and efficient natural and nature-based solutions for flood mitigation, shoreline protection, and coastal ecosystem preservation. Central to these predictions is the estimation of the vegetation drag coefficient (Cd). The present study undertakes a comprehensive evaluation of three distinct methodologies for estimating the drag coefficient: traditional manual calibration, calibration using a novel application of state-of-the-art metaheuristic optimization algorithms, and the integration of an empirical bulk drag coefficient formula (Tanino and Nepf, 2008) into the XBeach non-hydrostatic wave model. These methodologies were tested using a series of existing laboratory experiments involving nearshore vegetation on a sloping beach. A key innovation of the study is the first application of metaheuristic optimization algorithms for calibrating the drag coefficient, which enables efficient automated searches to identify optimal values aligning with measurements. We found that the optimization algorithms rapidly converge to precise drag coefficients, enhancing accuracy and overcoming limitations in manual calibration which can be laborious and inconsistent. While the integrated empirical formula also demonstrates reasonable performance, the optimization approach exemplifies the potential of computational techniques to transform traditional practices of model calibration. Comparing these strategies provides a framework to determine effective methodology based on constraints in determining the vegetation drag coefficient.

Semicircular Coastal Defence Structures: Impact of Gap Spacing on Shoreline Dynamics during Storm Events

Coastal erosion poses significant challenges to shoreline management, exacerbated by rising sea levels and changing climate patterns. This study investigates the influence of gap spacing between semicircular coastal defence structures on shoreline dynamics during storm events. The innovative design of these structures aims to induce a drift reversal of prevalent sediment transport while avoiding interruption of alongshore sediment drift, thus protecting the beach. Three different gap spacings, ranging from 152 m to 304 m, were analysed using the XBeach numerical model, focusing on storm morphodynamic behaviour. Methodologically, hydrodynamic and morphodynamic analyses were conducted to understand variations in significant wave heights adjacent to the structures, in accretion and erosion volumes, and changes in bed level under storm conditions. The study aims to elucidate the complex interaction between engineered coastal protection solutions and natural coastal processes, providing practical insights for coastal management practices. Results indicate that installing semicircular coastal defence structures influences sediment dynamics during storm events, effectively protecting stretches of the coast at risk. Optimal gap spacing between structures is crucial to mitigating coastal erosion and enhancing sediment accumulation, offering a sustainable shoreline protection approach. The findings underscore the importance of balanced location selection to optimize protection benefits while minimizing adverse morphological effects. Overall, this research contributes to advancing knowledge of hydro-morphological phenomena essential for effective coastal engineering and informs the design and implementation of more sustainable coastal protection strategies in the face of increasing coastal erosion and sea level rise challenges.

Coupled Short-Ig Wave Dunamics Over A Shallow Barrier Reef

Reef barriers play a major role many coral islands, by sheltering the lagoon from the ocean wave energy and then creating a unique habitat for many species. This filtering action becomes increasingly crucial for ecosystems health and shoreline protection in the context of climate change and related sea level rise, degradation of coral systems and modification of wave conditions. A strong research effort has therefore been engaged by the coastal oceanographers community for the last two decades to improve our knowledge and prediction skills of wave dynamics over coral reef systems. A widely reported observation is the importance of infragravity waves (IG) over wave-driven reef systems, whether fringing or barrier reefs. IG are primarily forced by groups in the incoming short-wave (SW) field, either by the release of bound waves or the breakpoint oscillations (Bertin et al. 2018). IG period typically ranges between 30 and 200s, which makes them prone to excite or interact with natural seiching modes in reef-lagoon systems often ranging in the Very Low Frequency (VLF) band. Further research efforts are now necessary to better understand the interaction between long IG/VLF oscillations and SW field. In particular, long waves are expected to play a dynamic depth-filtering role on SW energy, acting as long carrier wave able to promote the propagation of larger SW groups by IG/VLF crests. More generally, the spectral energy transfers over the reef crest-flat system and their relative importance w.r.t. frictional and breaking dissipation are not fully understood over the complete range of surface waves. The aim of the present study is to analyse and to discuss a series of field observations performed on the barrier reef of Maupiti Island, French Polynesia. A particular focus is placed on the interaction between SW and IG wave fields across the reef crest-flat system.

A global meta-analysis on the drivers of salt marsh planting success and implications for ecosystem services

Planting has been widely adopted to battle the loss of salt marshes and to establish living shorelines. However, the drivers of success in salt marsh planting and their ecological effects are poorly understood at the global scale. Here, we assemble a global database, encompassing 22,074 observations reported in 210 studies, to examine the drivers and impacts of salt marsh planting. We show that, on average, 53% of plantings survived globally, and plant survival and growth can be enhanced by careful design of sites, species selection, and novel planted technologies. Planting enhances shoreline protection, primary productivity, soil carbon storage, biodiversity conservation and fishery production (effect sizes = 0.61, 1.55, 0.21, 0.10 and 1.01, respectively), compared with degraded wetlands. However, the ecosystem services of planted marshes, except for shoreline protection, have not yet fully recovered compared with natural wetlands (effect size = −0.25, 95% CI −0.29, −0.22). Fortunately, the levels of most ecological functions related to climate change mitigation and biodiversity increase with plantation age when compared with natural wetlands, and achieve equivalence to natural wetlands after 5–25 years. Overall, our results suggest that salt marsh planting could be used as a strategy to enhance shoreline protection, biodiversity conservation and carbon sequestration.

The Effects Of Overtopping On Green/Grey Infrastructure

This paper presents results of a reduced (1:8) scale experiment investigating the performance of hybrid structural (gray) and natural-based (green) infrastructure for wave overtopping reduction. Experiments were scaled to a 1:8 geometric scale based on 1:2-scale experiments conducted during the Summer of 2023 at Oregon State University. Seven wave conditions were tested, with (model-scale) wave periods ranging from 1 to 2 seconds and wave heights ranging from 6.0 to 7.5 cm. These wave conditions were conducted throughout two configurations: a seawall-only (baseline) configuration and a configuration with the seawall in combination with a mangrove forest installed seaward of the wall. The total volume of overtopped water was measured for each wave condition. Results indicated that adding mangroves reduced overtopping for all wave conditions, with an average of 32.1% reduction in overtopped volume compared to the baseline configurations. This reduction falls within the range of preexisting overtopping rates. Results from these experiments can assist engineers in understanding the performance of hybrid coastal infrastructure to design effective and sustainable shoreline protection.

Climate Change: Effects on Salinity in Florida’s Estuaries and Responses of Oysters, Seagrass, and Other Animal and Plant Life

Florida’s economically important estuaries could be heavily impacted by sea-level rise and altered river flow, both caused by climate change. The resulting higher salinity, or saltiness of the water, could harm plants and animals, alter fish, and bird habitat, and reduce the capacity of estuaries to provide such important services as seafood production and the protection of shorelines from erosion. This publication contains information for stakeholders, students, scientists, and environmental agencies interested in understanding how changes in salinity impact Florida’s estuaries.

渭河干流甘肃段河岸线空间变化数据集（2008、2015、2022年）

As the largest tributary of the Yellow River, the Weihe River has an important influence on the Yellow River in terms of both its flow and sediment load. Carrying out spatial and temporal evolution monitoring of the river shorelines is an important basis for grasping the hydrological changes of the river in the basin. In this study, we used the high-frequency and resource satellite image data of the Gansu section of the Weihe River in 2008, 2015 and 2022 as the base map, and extracted the river shorelines of the Gansu section of the Weihe River through the processing of image ortho-correction, alignment, fusion, mosaicing and cropping; combining with the image characteristics of the image, we adopted the method of interactive deciphering, including the Weihe River management range line, the Weihe River waterfront boundary line, and the Weihe River outer edge boundary line. Additionally, high-precision UAV aerial image data were utilized, integrating typical areas and important markers on the image base map data to ensure the reliability of river shoreline extraction. This dataset can provide data support for studying the hydrological dynamic monitoring and driving mechanisms of the Weihe River main stream. Furthermore, it can serve as basis for making informed decisions regarding the protection of river and lake shorelines and the ecological management of the river.

Evaluating the Ability of Constructed Intertidal Eastern Oyster (Crassostrea virginica) Reefs to Address Shoreline Erosion in South Carolina

The application of nature-based solutions to address shoreline erosion and the loss of salt marsh in coastal South Carolina has centered around the creation of intertidal oyster (Crassostrea virginica) reefs that act as natural breakwaters. The installation of such living shoreline materials often results in a rapid accumulation of fine sediments, followed by wild oyster recruitment to suitable materials, and then more gradually the growth of salt marshes (primarily Spartina alterniflora). Leveraging more than two decades of oyster reef restoration and living shorelines research at the South Carolina Department of Natural Resources, this study quantitatively assessed performance rates for both percent oyster cover and marsh protection in relation to reef age. Determining such rates will serve to inform the expectations of prospective adopters of living shorelines as to the timeframes of some of the biological processes, as measures of performance success, that will occur following material installation. Performance success was investigated in terms of recruitment of oysters to installed materials and the creation of new marsh habitat or protection of existing marsh from erosion. Reef age was an important determinant of reef “success”, with significant relationships between reef age and both performance success metrics. Percent oyster cover reached 40% by two years post-installation and 50% by four years post-installation, indicative of high rates of oyster recruitment. The relative marsh protection rate of living shorelines compared to unprotected reference plots was 0.4 m yr-1 Reef performance differed based on bank substrate firmness, bank width, shoreline morphology, and location relative to the Intracoastal Waterway (ICW). Firmer bank substrate was associated with greater percent oyster cover. Broader bank width was associated with greater marsh protection. Higher percent oyster cover measurements were observed on straight, natural shorelines and reefs located along the ICW. Reefs located on the ICW were also associated with greater marsh protection than reefs at non-ICW sites. Further, this study demonstrates that bagged oyster shell reefs are capable of providing shoreline protection services for more than a decade and can endure multiple intense storm events. The results of this study were also used to facilitate the implementation of new living shoreline regulations in coastal South Carolina in the hope of broadening adoption of this approach to addressing shoreline erosion and salt marsh habitat loss.

Remote Sensing Image Segmentation of Wetlands in Macau Based on Machine Learning

Wetlands are essential components of our natural ecosystems, performing critical functions that contribute to biodiversity conservation, water purification, climate regulation, and shoreline protection. Remote sensing classification of wetlands, wetland resource surveys and other wetland research is booming, for the development of environmental protection policies continue to provide reliable data. Macau is a coastal city with rich wetland resources, but there is no relevant research on wetlands in Macau. In this paper, we use the high spatial resolution remote sensing data from Gaofen-2 satellite to extract the wetlands of Macau SAR to fill the gap of related research. This paper used two distinct machine learning classifiers, including Random Forest (RF) and Support Vector Machine (SVM), to analyse the high spatial resolution remote sensing data of GF-2 satellite in order to extract wetlands in Macau Special Region Area. In this research, the accuracy of RF model is much higher than that of SVM model, comparing the indexes of overall accuracy (OA) and Kappa coefficient. After analysing the resultant images generated after segmentation, the image segmentation result of RF model is better than that of SVM model. As for the RF model, the overall accuracy (OA) is 0.9941 and Kappa coefficient is 0.9899.

Analysis of Interregional Commuters Traffic Delay Induced by Shoreline Protection of Different Areas of the San Francisco Bay Area

Analysis of Interregional Commuters Traffic Delay Induced by Shoreline Protection of Different Areas of the San Francisco Bay Area

Artificial reef biofouling community impacts on ecosystem metabolism and biogeochemical cycling in estuarine waters of the northern Gulf of Mexico

Artificial reefs increase hard bottom habitat and bolster shoreline protection in coastal waters. Reefs are rapidly colonized by biofouling communities which can potentially alter ecosystem metabolism. Despite the high biomass and ubiquitous nature of biofouling communities, little is known about their ecosystem metabolism or role in biogeochemical nutrient cycling. Using a combination of laboratory and field-based methods, this study focused on the metabolic activity of artificial reef biofouling communities and their potential to contribute to water column hypoxia in a shallow subtropical estuary. Study objectives aimed to (1) measure in situ dissolved oxygen (DO) concentrations in surface and bottom waters along reef transects during summer months when episodic hypoxic events typically occur, (2) estimate respiration rates in relation to nutrient regeneration in the absence versus presence of biofouling communities, and (3) examine seasonal shifts in trophic structure by relating elemental C:N ratios and stable nitrogen isotope (δ15N) values of the biofouling community across eight sample periods. In situ DO in bottom waters was low near high profile reefs. Water column respiration and nutrient regeneration rates were comparable to other estuaries. Respiration and regeneration rates of ammonium and phosphate were all manifestly higher in the presence of a biofouling community. Biofouling metabolic-driven processes were higher at low profile reefs than at high profile reefs. Seasonal shifts in biofouling elemental composition indicated by higher C:N and lower δ15N during cooler months and lower C:N and higher δ15N during warmer months reflected a transition from a more autotrophic community in winter to a more heterotrophic community during the rest of the year. Our results demonstrate that artificial reef biofouling communities can potentially contribute to hypoxic conditions in coastal waters of the northern Gulf of Mexico.

Oysters' Integration on Submerged Breakwaters Offers New Adaptive Shoreline Protection in Low‐Energy Environments in the Face of Sea Level Rise

AbstractSea level rise (SLR) and increasing storm frequency threaten coastal environments. Engineering solutions such as breakwaters will become ineffective for wave attenuation and erosion control due to SLR. As a natural alternative, oysters create three‐dimensional, complex reef structures that attenuate wave energy and increase sedimentation rates. If coupled with breakwaters, oysters may maintain breakwaters' efficiency over time as they are expected to grow with SLR. Here, we measured bathymetric changes over 3 years (via GPS) and wave dampening due to four‐made intertidal breakwaters within a small cove of the Choptank River (MD, USA). Then, we modeled the coupling of such gray structures with oysters through Delft3D‐SWAN to evaluate the performances of such hybrid solutions on coastal protection, under future scenarios of SLR and climate change. Modeling hydrodynamic results showed a gradual reduction in wave attenuation due to SLR. However, when oysters were included in the modeling, wave dampening in 100 years was 75% and 60% greater than gray breakwaters, at high and low tides, respectively. Morphodynamic results showed increasing net export of sediment from the coast due to SLR. Oyster addition also provided shoreline protection and sediment retention in 100 years compared with the use of breakwaters alone, thanks to oysters' capability to grow with SLR. The coupling between oysters and breakwaters may represent a valuable and effective methodology to protect our coast over a changing climate and a rising sea, where optimal conditions for oyster survivability occur and are maintained over time.

Machine Learning-Based examination of recent mangrove forest changes in the western Irrawaddy River Delta, Southeast Asia

Mangrove forests serve as a significant carbon sink and provide effective shoreline protection against devastating winds. However, these forests are facing an unprecedented decline in tropical and subtropical large deltas due to human activities and climate change. This study focuses on quantifying the dynamic changes of mangrove forests in the Western Irrawaddy River Delta (WIDR), which is part of Myanmar’s largest delta in Southeast Asia, Remote sensing images from 1988 to 2022 were utilized alongside a machine learning approach to analyze these changes. The findings demonstrate a significant decline of mangrove forests within the WIRD, with a reduction in area by 45.35% over the past 35 years. Additionally, the patches of mangrove forests have become increasingly fragmented. Losses predominantly occurred in the inland regions, while gains were observed along the seaward edges, suggesting progradation towards the sea, which compensated for a net loss of 2,812.32 ha during the study period. The intensification of human activities, specifically deforestation and aquaculture pond utilization, appears to be the leading cause of catastrophic internal degradation within the WIRD’s mangrove forests. Contrary to the influence of local sea level rise or variations in suspended sediment discharge into the WIRD, this study suggests that the persistent retreat of mangrove forest fringes is controlled by large waves generated by the southwest monsoon. Estuarine barriers situated in the WIRD act as buffers, dissipating wave energy and facilitating seaward growth. of mangrove forests. Our study reveals a significant pattern in the WIRD, where landward mangrove forest loss coincided with seaward mangrove forest gain. This work underscores the importance of addressing landward mangrove forest loss and recognizing the emergence of seaward gains in the WIRD, providing valuable insights for fostering successful and sustainable mangrove management and protection initiatives.