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The intensity of coastal erosion is a measure of the strength of erosion processes affecting coastal areas. Traditionally, assessments of coastal erosion intensity have relied on singular indices, such as the rate of shoreline retreat or erosion, often prioritizing higher rates over lower ones. This approach, however, lacks comprehensive consideration and scientific rigor. In this study, we adopt a more holistic approach by examining the Qionghai-Wanning coast on the eastern side of Hainan Island. We selected four indices that reflect local conditions and influence coastal erosion strength: Annual rate of shoreline change (T1), Beach annual down-cutting rate (T2), Beach slope (T3), Average particle size of the beach (T4). These indices were used to comprehensively evaluate the erosion intensity of the Qionghai-Wanning coast. The evaluation results categorized the study area into six grades: serious erosion (3.45%), strong erosion (6.90%), erosion (20.69%), micro erosion (44.38%), stabilization (20.69%), and accretion (3.45%). The findings indicate that, under the broader environmental trends of global warming and rising sea levels, most sandy coasts exhibit micro-erosion intensity. Areas experiencing strong and serious erosion are predominantly influenced by human activities, such as those occurring in promenade bays, artificial islands, and harbors. To further understand the relationship between these factors and erosion intensity, we employed the Spearman correlation coefficient method. The analysis revealed that the T1 and the T2 are the primary factors influencing coastal erosion intensity, with the T4 serving as a secondary factor. These factors collectively impact the force and energy absorption of the coast through wave and tidal actions, ultimately determining the intensity of coastal erosion. The multi-index assessment method for coastal erosion intensity demonstrated an accuracy of 82.75%, providing a scientific basis for the management, protection, and restoration of coastal areas. [ABSTRACT FROM AUTHOR]

In coastal erosion studies, the erosion and accretion index is a vital research tool for analyzing types of erosion and accretion. This index is primarily empirical or semi-empirical and is usually validated through tank experiments or open beach datasets, resulting in significant variation across different beach environments. In this study, 11 beach profiles of eight beaches measured along the Qiongzhou Strait in China, measured from 2018 to 2021, were analyzed to quantitatively determine coastal erosion or accretion by calculating each profile's volume change per unit width. Additionally, sediment and wave data were used to calculate five erosion and accretion indices monthly to determine erosion and accretion conditions. These conditions were then compared with actual beach erosion and accretion data to evaluate the applicability of various discriminant indices. Furthermore, optimizing the threshold values of discriminant indices. The results show that: (1) Overall annual erosion and accretion are minimal, but seasonal variation is significant for beaches on both sides of the Qiongzhou Strait; (2) The five discriminant indices have some limitations in this study area, necessitating careful consideration when applying them to headland bay arc-shaped beaches with fetch-limited environments like the Qiongzhou Strait; (3) The selection of discriminant index parameters and their respective contribution degree of each parameter affects the formula's applicability, with two-parameter formulas proving superior to the three-parameter formula in the study area; (4) Beach environmental factors, particularly those influenced by headlands and fetch-limited environments, impact the indices' applicability; (5) Increasing the threshold value to a certain extent can improve the formula's applicability. [ABSTRACT FROM AUTHOR]

Literature shows that tourists can make significant financial contributions towards efforts of erosion prevention, but very few studies are done in the context of developing countries, especially to protect World Heritage sites. This paper provides the first estimates of willingness to pay (WTP) for differing coastal erosion measures by domestic and foreign tourists visiting Hoi An, an UNESCO World Heritage site located in Vietnam. Using a discrete choice experiment, our study presents several new and important findings. Tourists support visible protection structures and trees on beaches even though these hard measures can affect the natural aesthetics. There exists preference heterogeneity among tourists. Most importantly, our analysis shows that WTP of each tourist is USD $13.45, nearly seven times greater than WTP by local residents estimated in previous literature for a similar erosion protection program. [ABSTRACT FROM AUTHOR]

The Bay of Bengal has been at the heart of human civilisation and trade for many centuries. Accordingly, this oceanic space has seen influx of people from around the world including European traders who plundered natural wealth of this region for many years. Unabated exploitation of natural resources has been the primary reason for deterioration of environment of this part of the world. To add to this, supporting a growing population through unsustainable anthropogenic activities for decades is considered a primary cause for deterioration of marine life, habitats, coastal and marine ecosystems and numerous ocean ecosystem services of this oceanic space. Since the health of the oceanic space is critical for survival of life of Earth, a detailed study of the impacts of a growing population on the coastal environment of the Bay is considered important. Unfortunately, since the anthropogenic activities causing this deterioration are numerous, they cannot be covered in one paper. Hence, only a select few critical anthropogenic activities causing coastal erosion, resource degradation, and marine pollution are being analysed here. The study shows that as a result of increasing population, terrestrial activities such as increasing built up area, industries, land use activities, fisheries and aquaculture, and construction of shore protection structures have resulted in reduced coastal vegetation and increased pollution of the ocean. As a result the coastal landscape is witnessing increased coastal erosion, coastal flooding and inundation, loss of vegetation and faunal communities especially fishes. While local initiatives and projects reflect a positive commitment to address resource degradation and to create resilient coastal ecosystems, these efforts need to be transformed into achievements by dedicated and nuanced involvement of all stakeholders, especially the public, for the desired results. [ABSTRACT FROM AUTHOR]

Coastal hazards threaten properties, infrastructure, and cultural sites around Aotearoa New Zealand's (hereafter Aotearoa) coastline and sea-level rise (SLR) will escalate this problem. At present it is unclear how archaeological sites will be affected by future coastal erosion and inundation. In this paper we combine national-scale archaeological and environmental datasets to provide a first-pass overview of archaeological heritage at risk in Aotearoa. Two key national-scale datasets are utilized: (1) coastal sensitivity index (CSI) developed by the National Institute of Water and Atmospheric Research; and (2) ArchSite, Aotearoa's archaeological site database. The integrated datasets produce insights into the sensitivity of coastal archaeology to SLR and associated hazards, which are vital to planning for the loss of coastal archaeological sites. More than half (∼55%) of recorded coastal archaeological sites around Aotearoa are midden (n = 4938) and about 25% (n = 2271) are earthworks. In total, ca. 12% (9054) of all known archaeological sites are within 1000 m of soft shore shorelines. Of this total, only about 3% (302) of sites are burials, but the loss of these 302 burial sites would have very high cultural impact. Coastal erosion is a particularly important threat to archaeology as it would permanently remove sites, whereas the risk of site removal by coastal flooding inundation is lower. Our results show that about 22% (1954) of coastal archaeological sites are located on landforms that are sensitive to SLR-driven erosion: 29% (2660) of archaeological sites are located on foredune barrier beaches, 23% (2059) on foredune barrier plains, 14% (1283) on beaches, and 9% (808) on beach ridge barriers. This work draws attention to the scale of coastal archaeology in Aotearoa that needs adequate documentation, preservation, and potentially protection in the face of SLR. Robust coastal erosion and inundation datasets are needed to more deeply understand potential SLR-driven impacts on coastal archaeology and provide a scientific foundation for considering future adaptation options. [ABSTRACT FROM AUTHOR]

Coastal risk assessment is crucial for coastal management and decision making, especially in areas already experiencing the negative impacts of climate change. This study aims to investigate the coastal vulnerability due to climate change and human activities in an area west of the Limassol district's coastline, in Cyprus, on which there have been limited studies. Furthermore, an analysis is conducted utilising the Coastal Vulnerability Index (CVI) by exploiting eight key parameters: land cover, coastal slope, shoreline erosion rates, tidal range, significant wave height, coastal elevation, sea-level rise, and coastal geomorphology. These parameters were assessed utilising remote sensing (RS) data and Geographical Information Systems (GISs) along a 36.1 km stretch of coastline. The results exhibited varying risk levels of coastal vulnerability, mainly highlighting a coastal area where the Kouris River estuary is highly vulnerable. The study underscores the need for targeted coastal management strategies to address the risks associated with coastal erosion. Additionally, the CVI developed in this study can be exploited as a tool for decision makers, empowering them to prioritise areas for intervention and bolster the resilience of coastal areas in the face of environmental changes. [ABSTRACT FROM AUTHOR]

The increase in natural disaster frequency, intensified by climate change, poses one of the greatest threats to coastal systems and low-lying areas worldwide. It is estimated that the Global Mean Sea Level (GMSL) could rise by approximately 2 m in the twenty-first century, alongside intensifying cyclonic events. Consequently, in Brazil, coastal natural disasters are likely to become more frequent and intense, especially in the southern region. Thus, this study aims to identify, map and discuss coastal natural disasters in municipalities exposed to the open ocean belonging to the coastal zone of Santa Catarina (SC), Brazil, between 1998 and 2020. A review and dating of coastal natural disasters were conducted using four official databases: The Civil Defense of Santa Catarina website, Integrated Disaster Information System (S2ID), Santa Catarina Atlas of Natural Disasters, and the Brazilian Atlas of Natural Disasters. The data were organized into spreadsheets and mapped using QGIS 3.16.0 software. The results and main conclusions indicate: (1) More coastal disasters occurred in the north, central-north, and central sectors of SC between 1998 and 2020; (2) the period between 2010 and 2020 was more impactful; (3) the municipalities with the most records of coastal disasters were Balneário Barra do Sul, Itapoá and Florianópolis (considering only Ilha de Santa Catarina), respectively; (4) the three fastest-growing sectors are the north, central-north, and central; and (5) the seasons of autumn, spring, and winter, respectively, are more impacting for the study area. [ABSTRACT FROM AUTHOR]

This study aimed to estimate the economic benefits of the mangrove ecosystem resulting from coastal rehabilitation efforts in the coastal area of Karawang Regency, West Java Province, Indonesia. The estimation results are crucial for convincing stakeholders, including the government, that the budget allocated for coastal rehabilitation will provide significant benefits for human well-being and the sustainability of coastal ecosystems. The study employed an economic valuation analysis method, focusing on the three areas most severely affected by coastal erosion in Karawang Regency. The results showed that the total annual economic benefit from mangrove planting as part of coastal rehabilitation in these areas amounted to IDR 4,257,468,324,946. These findings are intended to support efforts to achieve the Sustainable Development Goals (SDGs). [ABSTRACT FROM AUTHOR]

This study analysed long-term shoreline change, the influence of erosion, and adaptation strategies in coastal Ghana. The change between 1972 and 2021 was analysed using Landsat satellite images and the Digital Shoreline Analysis System (DSAS v.5.0), and adaptation strategies were revealed through field observations. The End Point Rate (EPR), Linear Regression Rate (LRR), and Weighted Linear Regression (WLR) were used to estimate the rate of change, whereas the Net Shoreline Movement (NSM) and Shoreline Change Envelope (SCE) were used to calculate the distances of change. The coefficient of shoreline armouring (K) index was used to evaluate the grade of artificial or human interventions on the coast. The erosion rates for the EPR (− 107.6 m/year, or 95.0%) and LRR (− 75.7 m/year, or 99.3%) were higher than the accretion rates of (28.5 m/year, or 5.0%) and (33.6 m/year, or 0.7%), respectively. The NSM recorded maximum erosion (− 14,080 to − 10,840 m) and accretion (1107 to 2135 m) with an average distance of − 4943.1 m. The SCE estimated a maximum (14,080.5 m) and minimum (813.8 m) distances with an average distance change of 5557.9 m. The central coast experienced erosion at average rates of − 119.0 m/yr, − 89.6 m/yr, and − 94.0 m/yr, according to EPR, LRR, and WLR statistics. The eastern coast observed lower erosion rates than the central coast, with rates of − 75.3 m/yr, − 53.2 m/yr, and − 41.9 m/yr for the EPR, LRR, and WLR statistics, respectively. Since 1972, there has been a significant increase in artificial coastal structures on Ghana's central and eastern coasts. The central coast has reached a maximal level of shoreline armouring index, while the eastern coast has reached a minimal level. Although hard protective measures have been implemented on most parts of the coast for adaptation, improved policy initiatives on soft and nature-based protection measures are encouraged based on their favourable ecological impact and economic effectiveness. [ABSTRACT FROM AUTHOR]

Beach erosion and coastal protection are complex and interconnected phenomena that have a substantial impact on coastal environments worldwide. Among the various coastal protection measures, seawalls have been widely implemented to mitigate erosion and protect coastal assets. However, the interrelationship between beach erosion and seawalls remains a critical topic for investigation to ensure effective and sustainable coastal management strategies. Seawalls impact the shoreline, particularly through the "end effect", where the seawall functions similarly to a groin, causing erosion on the downdrift side relative to the direction of wave approach. This study provides a detailed analysis of the interplay between beach erosion and seawall structures in Loc An, Vietnam, employing both remote sensing and numerical approaches. Sentinel-2 images were employed together with an analytical solution to observe the shoreline change at the Loc An sand spit and to determine input values for the numerical model. Based on the shoreline dynamics, a numerical scheme was employed to study the shoreline evolution after the construction of a seawall. Our findings show that the shoreline evolution can be divided into three stages: (1) The first stage corresponds to the elongation of the sand spit without interference from coastal structures. (2) The second stage shows the effect of jetties on the shoreline, as signaled by the buildup of sand updrift of the jetties. (3) The third stage shows the effectiveness of the seawall, where the shoreline reaches its equilibrium condition. The study provides a quick and simple method for estimating shoreline diffusivity (ε) in situations where measured data is scarce. [ABSTRACT FROM AUTHOR]

The performance of an intermediate-scale modular, permeable, floating breakwater comprised of an array of vertical screens is optimized and tested. A distinctive attribute of this breakwater design is its adaptive capacity to fluctuating water levels owing to its floating configuration, thereby preserving its efficacy during high tide and storm tide scenarios—an advancement over conventional bottom-mounted structures. The initial validation of the concept was tested in a laboratory wave basin in regular waves, which demonstrated promising results for three porous panels. Next, the breakwater's design parameters were optimized using a finite difference computational fluid dynamics software, (FLOW-3D version 2023R2), considering porosity, spacing, and panel count. A scaled prototype, representative of a 1:2 ratio was then deployed during the summer of 2022 along the coast of Castine, ME, within a mesotidal, semi-sheltered system characterized by tidal currents and waves. Notably, the breakwater succeeded in attenuating half of the wave energy for periods shorter than 4 s, evidenced by transmission coefficients below 0.5, making this technology suitable for locally generated waves with shorter periods. During storm events, instantaneous transmission coefficients decreased to as low as 0.25, coinciding with significant wave heights exceeding 0.8 m. Additionally, the efficacy of wave attenuation improved slightly over time as biofoulants adhered to the structure, thereby enhancing drag and mass. [ABSTRACT FROM AUTHOR]

Tombolos are ephemeral coastal landforms, which may form and disappear over short geological time periods. Thus, they are susceptible to marine processes. During the last decades, however, climate change and the subsequent sea level rise seems to have affected a large part of the world's coastlines. Tombolos are particularly prone to the imminent sea level rise. Many tombolos globally may disappear in the coming decades. Our work aims to quantify the susceptibility of the tombolos along the Greek coastline in relationship to the sea level rise. We mapped all Greek tombolos and created an online (and public) geodata base. For each tombolo, we measured its primary physiographical characteristics (e.g., length and width), and also its height above sea level. Based on that, we applied two scenarios proposed by the IPCC concerning the future sea level rise (RCP 2.6 and RCP 8.5), in order to check to what extent the Greek tombolos may disappear or face extreme erosion in the next few decades. Our results indicate that more than half of the Greek tombolos will be fully flooded and disappear in 100 years even under the optimistic scenario. Even those that remain will still face severe erosion problems. [ABSTRACT FROM AUTHOR]

This article presents a diachronic study of evolution along the coastline of Noirmoutier Island in France, a sandy shore particularly susceptible to erosion and submersion risks, which are exacerbated by climate change due to two-thirds of its territory being below sea level. The study is based on an analysis of aerial images covering a period of 72 years, divided into five distinct periods: 1950–1974, 1974–1992, 1992–2000, 2000–2010, and 2010–2022. The methodology used combines two complementary approaches: the Digital Shoreline Analysis System (DSAS) for taking linear measurements of the erosion and accretion that have taken place along various shorelines, and the surface method to evaluate the amount of surface lost or gained between different shorelines while calculating the uncertainties associated with the obtained results. The overall trend observed between 1950 and 2022 indicates that the Noirmoutier coastline studied has gained surface area (81 hectares) at an average rate of +0.57 ± 0.06 m per year. The article then presents an application of the method developed by Durand and Heurtefeux in 2006 to estimate the future position of the shoreline. A map of the local area is also provided, identifying the areas susceptible to coastal erosion by 2052 and by 2122, in accordance with the provisions of the Climate and Resilience Law adopted in France on 22 August 2021. The results reveal that there are many sources of uncertainty in predicting the future evolution of the shoreline using this methodology. Therefore, it is crucial to consider these uncertainties when planning future coastal management actions and adopting appropriate adaptation methods to counteract unforeseen developments. [ABSTRACT FROM AUTHOR]

Coastal erosion has posed significant challenges to sustainability and socio-economic stability along Senegal's coastline, leading to substantial infrastructure losses. Using GIS multi-criteria decision analysis (MCDA), two sub-indices were derived for Senegal's coastal departments: the physical susceptibility (PSI) and the social-economic vulnerability (SVI) to coastal erosion. The integrated coastal erosion vulnerability (ICER) model was derived by their aggregation. A total of 26 criteria were used, 18 for PSI and 8 for SVI. The criteria weighting coefficients of the sub-indices were determined using the analytic hierarchy process (AHP). Validation of the model accuracy was performed using receiver operating characteristic (ROC) curves that were calculated based on a created coastal erosion cadaster and true positive (TP) sites and manually acquired true negative (TN) sites. The accuracy assessment confirmed the consistency of the physical susceptibility model (PSI) and proved that existing coastal erosion sites are within (5) very high susceptibility areas. Through the generated ICER, the coastal departments were divided into areas of (1) very low, (2) low, (3) medium, (4) high and (5) very high vulnerability to coastal erosion. Very high (5) and high (4) classes cover around 31% of the coastal departments, mostly encompassing a narrow coastal strip and low river valleys and mouths. The presented coastal susceptibility and vulnerability maps, with a spatial resolution of 30 m, identified problematic areas in Senegal's coastal departments and can help decision-makers in the construction of effective coastal zone management and sustainable development. [ABSTRACT FROM AUTHOR]

Due to climate change, waves have become increasingly stronger, making the analysis of beach changes before and after typhoons crucial for addressing beach erosion. This study utilized low-cost, high-efficiency video monitoring to analyze beach changes at 14 locations along Korea's east coast before and after typhoon impacts. Shorelines were extracted from 180 s average orthoimages using the Pixel Intensity Moving Average Extraction technique, and beach areas were calculated. The study focused on the recovery period following typhoon-induced erosion. During Typhoon Goni (2015), erosion reached up to 38% at Bongpo Beach, with a maximum affected area of 7,741 m2 at Goraebul Beach. Post-typhoon recovery exceeded 89%, with most beaches returning to pre-typhoon conditions. The erosion period averaged 7 d, while recovery took approximately 27 d. Erosion was significantly influenced by natural forces such as waves, tides, and wind. The erosion period showed minimal correlation with wave energy, whereas the recovery period exhibited some correlation. Further long-term analysis, incorporating additional wave data and typhoon impact periods, is needed. Future research will aim to collect extensive typhoon data to systematically analyze erosion and recovery cycles in relation to external forces.

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.

In coastal video monitoring, the direct linear transform (DLT) method with ground control points (GCPs) is commonly used for geo-rectification. However, current practices often overlook the impact of GCP quantity, arrangement, and the geographical characteristics of beaches. To address this, we designed scenarios at Chuam Beach to evaluate how factors such as the distance from the camera to GCPs, the number of GCPs, and the height of each point affect the DLT method. Accuracy was assessed by calculating the root mean square error of the distance errors between the actual GCP coordinates and the image coordinates for each setting. This analysis aims to propose an optimal GCP placement method. Our results show that placing GCPs within 200 m of the camera ensures high accuracy with few points, whereas positioning them at strategic heights enhances shoreline extraction. However, since only fixed cameras were used in this study, factors like varying heights, orientations, and resolutions could not be considered. Based on data from a single location, we propose an optimal method for GCP placement that takes into account distance, number, and height using the DLT method.

This article presents a diachronic study of evolution along the coastline of Noirmoutier Island in France, a sandy shore particularly susceptible to erosion and submersion risks, which are exacerbated by climate change due to two-thirds of its territory being below sea level. The study is based on an analysis of aerial images covering a period of 72 years, divided into five distinct periods: 1950–1974, 1974–1992, 1992–2000, 2000–2010, and 2010–2022. The methodology used combines two complementary approaches: the Digital Shoreline Analysis System (DSAS) for taking linear measurements of the erosion and accretion that have taken place along various shorelines, and the surface method to evaluate the amount of surface lost or gained between different shorelines while calculating the uncertainties associated with the obtained results. The overall trend observed between 1950 and 2022 indicates that the Noirmoutier coastline studied has gained surface area (81 hectares) at an average rate of +0.57 ± 0.06 m per year. The article then presents an application of the method developed by Durand and Heurtefeux in 2006 to estimate the future position of the shoreline. A map of the local area is also provided, identifying the areas susceptible to coastal erosion by 2052 and by 2122, in accordance with the provisions of the Climate and Resilience Law adopted in France on 22 August 2021. The results reveal that there are many sources of uncertainty in predicting the future evolution of the shoreline using this methodology. Therefore, it is crucial to consider these uncertainties when planning future coastal management actions and adopting appropriate adaptation methods to counteract unforeseen developments.

The Arctic rapidly warms and sea ice retreats, a large fraction of organic carbon (OC), currently stored in coastal permafrost will be released into the marine system. Once reintroduced into the active carbon cycle, this material will either be decomposed or buried on the shelf depending on its hydrodynamic and chemical properties. Currently, carbon estimates are based on bulk measurements, which does not take the hydrodynamic pathway of different fractions into account. Therefore, eight coastal permafrost locations have been sampled along the Canadian Beaufort Sea Coast, hydrodynamically fractionated and analyzed for their C, N, 13C and 14C content. We found that the matrix‐free fraction (low density <1.8 g/cm3, and high‐density >1.8 g/cm3; <38 μm) account for 77%–98% of the OC. By using a coastal classification combined with field data, our results showed that short coastal segments can become key players in delivering matrix‐free, easily degradable OC to the marine system. Plain Language Summary: Arctic coastlines consisting out of permafrost, permanently frozen ground, experience accelerated erosion due to rising global temperatures. This erosion poses a threat to local communities and releases thawed permafrost material into the Arctic Ocean. Permafrost coasts store significant amounts of organic carbon (OC), and as they thaw and erode, this carbon is released, impacting the climate through the potential release of CO2. Current estimates rely on bulk measurements, but the behavior of released OC in the ocean remains poorly understood. To address this, we used hydrodynamic fractionation on eight sampled coastal permafrost sites along the Canadian Beaufort Sea. By doing so we separate the material based on density and grain size. The results show that a significant portion of OC (77%–98%) falls into the low‐density and the high‐density fine (<38 μm) fraction, containing easily degradable plant‐rich material. Due to these two fractions short coastal segments can become key players for the delivery of degradable OC into the ocean. Key Points: Coastal types vary in size and density distribution, high‐density prevailing in weight and low‐density dominating organic carbon contentBetween 77% and 98% of eroded organic carbon resides in the matrix‐free fraction, prone to degradation and CO2 releaseHydrodynamic fractionation and site‐specific properties contribute to integration of results into land‐ocean flux models [ABSTRACT FROM AUTHOR]

Defining the most suitable intervention to mitigate coastal hazards in a specific area, under an integrated coastal management strategy, is complex for several reasons including the lack of stakeholders’ consensus. In this respect, Cost-Benefit Analyses (CBAs) can help decision-makers to better understand the environmental, social and economic implications of a planned intervention. Nevertheless, CBAs are not yet largely applied in coastal management studies, as could be expected. Hence, this work aims to consolidate the use of a CBA to support coastal management decisions, considering its application to a real case study. The case study consists in evaluating the long-term impacts, benefits and costs of a detached breakwater for the protection of a coastal village located on the Portuguese northwest coast against flooding and erosion. This assessment was made based on the estimation of the costs of the structure and the benefits associated with the protection of the coastal community and natural areas, considering morphodynamics’ forecasts determined through numerical modelling. Out of several configurations defined based on length (L; in meters) and distance to the shoreline (D; in meters), four detached breakwater scenarios were selected. Results demonstrate that scenario L200D200 can be a feasible solution with overall low costs and low benefits; L300D400 can be an alternative solution with higher costs but higher benefits too. The consolidation of the CBA described is a step forward to improving the expedition of future analysis and proof of its potential in what concerns analysis at the local scale. [ABSTRACT FROM AUTHOR]

Formation and evolution processes of natural tombolos involve many interrelated geomorphological, sedimentary, oceanographic and anthropogenic factors, making their measurement and simulation an extremely difficult task. The present study attempts to fill this knowledge gap by detecting the natural tombolos in Greece, formed in the current sea level, through the statistical analysis of their morphometric and socio-environmental parameters. In addition, the long-term evolution of these coastal depositional landscapes has been determined by comparing old aerial photos taken in 1945 or 1960 and recent satellite images taken from 2020 to 2022. Two thirds of the twenty tombolos studied are subject to erosion, while eight are sporadically destroyed and turned into salients. The Greek tombolos are mildly or heavily exploited for touristic purposes, and fourteen of them are protected by national and international environmental laws. Future studies need to focus on the unstable type of these coastal landforms that are modified from tombolo to salient and vice versa to obtain helpful information about the morphodynamic conditions necessary for their evolution. [ABSTRACT FROM AUTHOR]

Coastal environments are complex systems that are influenced by a combination of natural processes and human activities. Scientific interest in the effects of coastal erosion/accretion and climatic change-related processes has greatly increased in recent decades due to the growing human development along coastal areas. This paper investigates the state and evolution of beach–dune systems for the 1977–2001 and 2001–2019 periods of the Mediterranean coast of Andalusia (Spain) using two different proxies: the dune toe line, which was used to track foredunes evolution, and the high-water line, which was used to assess shoreline evolution. Results showed a general erosional behavior of the studied beach–dune systems and identified cases where the main trend was altered through human interventions. During the 1977–2001 period, foredunes essentially showed erosion (54%), accretion (24%), and stability (22%) and shorelines showed accretion (40%) and erosion and stability (34% each). During the 2001–2019 period, foredunes essentially showed erosion (42%), stability (30%), and accretion (28%), and shorelines showed erosion (40%), accretion (34%), and stability (26%). Combining the evolution classes of each proxy (dune toe/shoreline) allows the behavior of both shoreline proxies to be assessed together and provides insights additional to those derived from the use of a single proxy. In this regard, Erosion/erosion (EE) and Accretion/accretion (AA) were the most frequent behaviors in the first and second periods. The results obtained provide additional insights on the nature and drivers of coastal change that aid local coastal managers and administrations in understanding erosion processes. The method can be applied to other areas around the world where a similar database is available. [ABSTRACT FROM AUTHOR]

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The analysis and prediction of the coastal erosion status are of great significance for maintaining the marine ecological environment, planning urban construction, and coping with climate change. Fangchenggang is located in the southwesternmost part of mainland China. It has the largest harbor in the western region, which provides access to the most convenient channel between southwest China and the Association of Southeast Asian Nations. With the rapid development of China's economy, coastal erosion has occurred in Fangchenggang, and ecological and environmental problems have become increasingly prominent. In this study, we mainly focus on the status analysis and prediction of Fangchenggang coastal erosion based on multisource remote sensing data. A systematic analysis and prediction methods for the coastal erosion state are studied. First, shoreline type changes are analyzed. The index of coastline type diversity is used instead of solely using length changes to analyze shoreline diversity, and the length change intensity is applied to quantify the degree of shoreline change over time for different types of shorelines. Next, the composite index of coastline utilization degree is introduced to further explore the impact of human activities on shorelines. Then, to study the effect of coastal erosion on different types of shorelines in Fangchenggang, the end point rate is used to obtain the coastal erosion rate. Finally, the shoreline trend prediction model for Fangchenggang is established through the spatial distribution of the coastal erosion rate, and we verified that the accuracy of the model is 82%. The model can provide technical support for the integrated prevention and control of coastal erosion hazards. [ABSTRACT FROM AUTHOR]

This study explores the impacts of climate change on coastal erosion, focusing on how rising sea levels, increased storm intensity, shifting ocean currents, and human activities contribute to the accelerated loss of coastal land. Through a comparative analysis of vulnerable regions--South Pacific Islands, Gulf Coast (USA), Coastal Bangladesh, and the East African Coast--the research highlights the environmental, socioeconomic, and cultural consequences of erosion. It emphasizes the urgent need for comprehensive mitigation strategies, including engineering solutions (e.g., sea walls, groynes, artificial reefs), nature-based measures (e.g., mangrove restoration, beach nourishment, wetland conservation), and robust policy frameworks. The findings underscore that while engineering solutions offer immediate protection, nature-based approaches provide sustainable, long-term resilience by restoring ecosystems and supporting biodiversity. Effective policy and governance, supported by international collaboration and local engagement, are crucial to implementing adaptive strategies that address both regional vulnerabilities and global challenges. This research aims to contribute to a better understanding of coastal erosion dynamics and inform policies that enhance coastal resilience against the impacts of climate change. [ABSTRACT FROM AUTHOR]

Erosion along the coastline of the Alaskan Arctic poses an existential threat to several communities. Rising air temperatures have been implicated in accelerating erosion rates through permafrost thaw, decreasing sea ice cover (increasing ocean fetch and wave energy), and shortening the duration of a shore-fast ice buffer, which all mean that erosion rates are higher in summer than they are in winter. However, the resolution of available satellite imagery has historically been too low to allow for the quantification of seasonal erosion rates across large areas of the Arctic, and so erosion rates are generally measured at annual to decadal time scales. This study uses PlanetScope high-resolution satellite imagery to calculate seasonal erosion rates in the Alaskan Arctic. Erosion rates as high as 38 cm/day (equivalent to 140 m/year) were measured using twice-annual images from 2017–2023 on two stretches of Alaska's Beaufort Sea coast: Drew Point and Cape Halkett. The highest erosion rates are measured in the summer, with winter erosion rates consistently below 10 cm/day (usually within error margin of zero) and summer erosion rates exceeding 20 cm/day in three out of the seven years of data. Summer erosion rates are shown to correlate well with local air temperatures in July–September, July sea surface temperatures, and with Beaufort Sea sea ice area in May–August. Wind speeds and number of windy days do not correlate well with summer erosion rates. This study demonstrates the feasibility of using PlanetScope imagery to calculate erosion rates at seasonal time resolution without field measurements and shows the magnitude of difference between summer and winter season erosion rates. [ABSTRACT FROM AUTHOR]

Sandy coastlines are very dynamic spaces affected by a variety of natural and human factors. In Central Chile, changes in oceanographic and wave conditions, modes of inter-annual climate variability such as El Niño Southern Oscillation (ENSO), and extreme events such as earthquakes and tsunamis condition the beach morphology. At the same time, direct human actions alter the arrival of sediments to the coast and their alongshore distribution. Despite the relevance of the beaches for this coastal region and the interesting relationship their morphology has with the aforementioned factors, there is a lack of robust morphological datasets to provide a deep characterization and understanding of the dynamism of the Chilean coast. Based on the information provided by satellite-derived shorelines (SDSs) defined by using the SHOREX algorithm, this paper characterizes the morphological changes of Playa Grande in Cartagena Bay (Central Chile) during the period 1985–2019. The shoreline position data are analyzed in the context of changing beach transforming elements, allowing for a better understanding of the changes according to multiple drivers. While some of these factors, such as earthquakes or coastal storms, have a punctual character, changes in wave patterns vary at different time scales, from seasonal to multi-annual, linked to climate phases such as ENSO. Its effects are translated into shoreline erosion and accretion conditioned by the morphology and orientation of the coast while influenced by the availability of sediment in the coastal system. According to that, a conceptual model of the dynamism and redistribution of sediment in the Bay of Cartagena is proposed. The work proves the high utility that the systematic analysis of multi-decadal SDS datasets obtained from the images acquired in the optical by the Landsat and Sentinel-2 offer for beach monitoring and understanding the coastal dynamism. [ABSTRACT FROM AUTHOR]

Krivova, M.; Olsen, M.; Allan, J.; Parrish, C.; Leshchinsky, B.; Senogles, A.; Herrmann, J., and Dundas, S., 2024. Vulnerability assessment of risk for a coastal highway in Oregon, U.S.A. Journal of Coastal Research, 40(4), 714–739. Charlotte (North Carolina), ISSN 0749-0208. Threading its way through Oregon, U.S. Highway 101 operates as a crucial conduit, intertwining functional necessity with the aesthetic appeal of sweeping coastal vistas. Unfortunately, many locations along this vital route are under constant threat from coastal hazards, such as seacliff erosion, landslides, and recurrent wave runup leading to overtopping and flooding. Given the daunting challenges associated with maintaining functional infrastructure in such rugged, dynamic terrain, as well as the balance between the preservation of the natural state of the coastline and the infrastructure providing access, sites must be prioritized for mitigation. Using quantitative assessment methods, such as the Coastal Vulnerability Index (CVI), can play a pivotal role in systematically identifying high-risk sites in need of remediation. Based on the findings of previous studies, the CVI was tailored to assess the vulnerability of the highway system to coastal geologic hazards. In this study, 71 hazardous sites were pinpointed for evaluation and possible remedial action. To capture the spectrum of hazards faced at each site, 26 parameters were used and classified into three primary categories, namely inundation, erosion, and landslides. This study presents a unique approach in implementing the CVI by considering the potential uncertainties in the calculations. The novelty lies in the usage of a Monte Carlo simulation to assign weights based on the uncertainties of each parameter. This innovative simulation approach enables assessment of the sensitivity of the overall CVI estimation based on the influence of parameter uncertainties. Ultimately, this approach provides a more robust, less subjective, and comprehensive vulnerability assessment process than current implementations of CVI that do not incorporate uncertainty. [ABSTRACT FROM AUTHOR]

The accelerated urban growth in Macaé had important consequences on socio-spatial organization, especially about housing spaces that became increasingly difficult to be accessed by the low-income population. The most devalued lands, such as mangroves and floodplains, were occupied by the low-income population. The proposal highlighted in this project focuses directly on the problem of rising sea levels and flooding in the urban space of Macaé, which is of social interest. A simulation of future scenarios with sea level rise above the current one, allowing the identification of areas flooded by marine transgression on a time scale of 100 years (for the year 2100). For this, the rate was chosen for the simulation: the greenhouse gas scenario RCP8.5, as given in IPCC's Fifth Assessment Report (AR5) of 2014. A radiative forcing that corresponds to more than 700 ppm CO2-eq, but less than 1500 ppm, the projected increase is 1 m to more than 3 m (medium confidence) and more than 3 m (medium confidence). This assessment is based on the average confidence in the contribution from thermal expansion and low confidence in the modeled contribution modeled contribution of the ice sheets. Therefore, the climate change-induced global mean sea level rise is caused by thermal expansion of ocean water and ocean mass gain, the latter being mainly due to a decrease in land ice mass. The estimated sea-level rise used for the projection of this study is 2.15, as proposed by Grinsted et al. in 2009. [ABSTRACT FROM AUTHOR]

The Arctic is experiencing rapid warming, which among other processes results in increasing erosion of coastal permafrost and the release of ancient organic carbon (OC) into the Arctic Ocean, which in turn might result in greenhouse gas emissions following its decomposition. Supply of terrigenous organic matter to the ocean affects near‐shore nutrient concentrations and the composition of microbial communities—highlighting the need to understand the fate of permafrost‐derived carbon in this fragile ecosystem. We incubated material from coastal Yedoma permafrost for 85 days in seawater collected during the Arctic Century expedition. During this experiment, 2.8 ± 1.4% of OC from coastal Yedoma was respired to CO2. Radiocarbon analysis revealed that 88 ± 15% of the released CO2 originated from ancient material (∼40,000 years), indicating that degradation of permafrost OC reintroduces old carbon into the short‐term carbon cycle. Hence, the permafrost climate feedback may be enhanced in the coming decades when coastal erosion accelerates. Additionally, 0.9 ± 0.3% of Yedoma OC was leached as dissolved OC. The observed net production of inorganic nitrogen during the incubation could potentially provide a negative feedback by stimulating primary production. Bacterial community analysis showed a succession of primary responders to biolabile substrates (e.g., Psychrobacter and Colwellia) followed by secondary consumers of less biolabile substrates (e.g., Maribacter and Pseudohongiella), plus a potential establishment of permafrost associated‐bacteria on particles. Overall, our data show that OC input from thawing permafrost stimulates bacterial dynamics, with likely implications for regional biogeochemical cycles and the Earth's climate. Plain Language Summary: The Arctic coast, primarily composed of permanently frozen deposits (permafrost), is experiencing accelerated thawing and erosion due to rising temperatures, four times the global average. As a result, substantial amounts of ancient organic carbon (OC), previously stored in ice‐rich deposits like Yedoma, can be released into the adjacent sea. In our 85‐day incubation experiment, approximately 3% of the OC from ancient permafrost was transformed into CO2 when added to seawater. Remarkably, the released CO2 has an age of around 40,000 years (equivalent to carbon stored in permafrost since the last ice age). This process, termed permafrost carbon feedback, involves ancient permafrost contributing previously freeze‐locked carbon to the modern carbon cycle, intensifying climate change. Microbial communities responsible for organic matter degradation originated from both seawater and the ancient Yedoma itself, suggesting "reactivation" of long‐frozen microbes. The study highlights the impact of collapsing permafrost coastlines on regional biogeochemistry and ecology, with potential repercussions for the global carbon cycle and climate. Key Points: ∼3% of the initial Yedoma organic carbon was respired by microbial communities to CO2 and dissolved inorganic carbon (DIC) over 85 days88 ± 15% of CO2 and DIC released during the incubations originates from ancient organic matter (∼40,000 years old)Seawater and ancient Yedoma microbes increased in abundance during incubation, suggesting both communities metabolize Yedoma organic matter [ABSTRACT FROM AUTHOR]

The intricate interplay of oceanic-atmospheric variations has intensified erosive processes on sandy beaches in recent decades, with climate change expected to exacerbate these impacts in the future. Projections for the southern Atlantic and Pacific regions of continental Latin America predict increased extreme events and heightened impacts on sandy beaches, highlighting disparities in studies addressing coastal erosion and its causes. To address these risks, a systematic review is proposed to analyze historical trends and projections, aiming to inform local-level studies and management strategies for at-risk coastal communities. Reviewing 130 research papers, insights reveal the influence of climatic events like El Niño and La Niña on coastal dynamics, as well as the effects of storm intensification and extreme events such as high-intensity waves and storm surges on Latin American coasts, resulting in ecosystem, economic, and infrastructure losses. Projections indicate a rise in the population inhabiting Low Elevation Coastal Zones (LECZ) by the century's end, emphasizing the urgent need for effective management and planning. Community engagement in erosion monitoring and adaptation programs is crucial for addressing these challenges and developing robust, sustainable, long-term adaptation strategies. This study aims to enhance the understanding of coastal erosion in Latin American communities addressing future coastal risks. [ABSTRACT FROM AUTHOR]

The dynamic shifts in shorelines due to erosion and deposition have become a significant challenge in coastal zone management, particularly in the context of climate change and rising sea levels. This paper evaluates the shoreline protection and efficiency of various wave-reducing breakwaters in the Vietnamese Mekong Delta. The delta exemplifies the coastal erosion issue faced by deltas worldwide. Landsat satellite images were used to establish a coastal development map for the period 2000 to 2022. The wave data in front and behind the breakwaters were analyzed to assess the wave reduction efficiency of various breakwater structures. Our results reveal that coastal erosion is deeply concerning, with almost 40% of the coastline experiencing severe erosion. Hotspot areas have been observed to reach annual erosion rates of nearly 95 m per year. The majority of provinces have adopted protective measures, with 68% of affected shorelines protected to some degree. Our results show breakwaters to be highly effective in reducing wave height, with a 62% reduction in waves reaching the shore. The process of creating offset has taken place in the area from the breakwater back to the mainland, with the rate of increase in compensation also quite fast at up to 3.1 cm/month. The stability of the pile–rock is very high; however, it is necessary to add rock to compensate for the settlement of the rock part. [ABSTRACT FROM AUTHOR]

Climate change-induced sea level rise, shoreline changes, and coastal erosion are projected to drive massive population displacement and mobility in Africa. This study was conducted to examine the pattern of shoreline changes, coastal erosion, land use/land cover dynamics, projections, and their implications on internal migration in Senegal, Kenya, and Tanzania, representing West and East Africa. The digitized shoreline was mapped into erosion, accretion, and trend analysis, which further explains the vulnerability and physical processes that could trigger human displacement within the context of environmental/climate migration. Analysis of land use and land cover dynamics was obtained from Landsat 5 TM of 1986, Landsat 7 ET of 2006, Landsat 8 OLI/TIRS of 2016, and Landsat 9 OLI/TIRS of 2022 and computed using ArcGIS 10.7 for land-use change and percentage change in square kilometers was conducted to examine land use/land cover dynamics and their contributions to the risk of coastal erosion in the study regions. The outcome of the shoreline analysis reveals that 972.03 sqkm of land has been lost to coastal erosion in Senegal from 1986 to 2022 with 2016–2022 described as the period with the highest in terms of land loss. In Kenya, −463.30 sqkm of land has also been lost to coastal erosion and agents of wave processes, with 1986–2006 recording the highest share of −87.74% loss of valuable land, while in Tanzania, −1033.35 sqkm of valuable land has been lost from 1986 to 2022 to coastal erosion, with 2006–2016 alone recording −10.4634% of land loss. The result of the land use/land cover percentage change analysis indicates a massive loss of vegetation cover with a significant increase in settlement representing urbanization. The scenario analysis of the shoreline at 10, 20, and 30 m indicates that 567 persons per sqkm at 10 m, 25,904.6 persons per sqkm at 20 m, and 25,904.5 persons per sqkm will be displaced in Senegal at 30 m. In Kenya, 57,746 persons per sqkm are projected to be displaced at 10 m while 1210.5 persons per sqkm will be displaced at 20 m and 7737.32 persons per sqkm will be displaced at 30 m. In Tanzania, the maximum population density projected to be displaced at 10, 20, and 30 m is 10,260.97 per sqkm. Structured questionnaires were administered to elicit responses from coastal dwellers on their perception of coastal erosion and climate migration as part of ground truthing and the result of the survey affirms that coastal erosion and its exposure are the major drivers of climate migration in the study area. [ABSTRACT FROM AUTHOR]

Public satellite platforms offer regular observations for global coastal monitoring and climate change risk management strategies. Unfortunately, shoreline positions derived from satellite imagery, representing changes in intertidal topography, are noisy and subject to tidal bias that requires correction. The seaward‐most vegetation boundary reflects a change indicator which shifts on event–decadal timescales, and informs coastal practitioners of storm damage, sediment availability and coastal landform health. We present and validate a new open‐source tool VedgeSat for identifying vegetation edges (VEs) from high (3 m) and moderate (10–30 m) resolution satellite imagery. The methodology is based on the CoastSat toolkit, with streamlined image processing using cloud‐based data management via Google Earth Engine. Images are classified using a newly trained vegetation‐specific neural network, and VEs are extracted at subpixel level using dynamic Weighted Peaks thresholding. We performed validation against ground surveys and manual digitisation of aerial imagery across eroding and accreting open coasts and estuarine environments at a site in Scotland. Smaller‐than‐pixel vegetation boundary detection was achieved across 83% of Sentinel‐2 imagery (Root Mean Square Error of 9.3 m). An overall RMSE of 19.0 m was achieved across Landsat 5 & 8, Sentinel‐2 and PlanetScope images. Performance varied by coastal geomorphology, with highest accuracies across sandy open coasts owing to high spectral contrast and less false positives from intertidal vegetation. The VedgeSat tool can be readily applied in tandem with waterlines near‐globally, to support adaptation decisions with historic coastal trends across the whole shoreface, even in normally data‐scarce areas. [ABSTRACT FROM AUTHOR]

As escalating environmental pressures threaten the world's beaches, understanding the driving factors influencing their geomorphological changes is of critical global importance. This study focuses on the morphological changes of Sigeng beach adjacent to Changhua River Mouth in Hainan Island, China through decadal monitoring of shoreline and profile topography and tries to illuminate the natural and anthropogenic factors that drove geomorphological changes. The results showed that Sigeng beach undergone significant changes between 2008 and 2024, with notable accretion at the northernmost and southernmost and general erosion at other sections. The shoreline change rates ranged between -18.4 m/yr and 13.0 m/yr, with the average rate of -1.9 m/yr, indicating overall erosion. The net longshore sediment transport (LST) rates along Sigeng beach was estimated through the combination of the cross-shore (profile) and longshore (shoreline) changes. The overall direction of net LST along the beach were southward, except for the northern section where the direction was northward due to the diffraction of NE waves by the long sand spit at the northernmost. The net LST rates at each profile varied from 0.8×104 m³/yr to 3.5×104 m³/yr. The main factors controlling Sigeng beach evolution, including seasonal wave action and reduction in fluvial sediment load, followed by sand spit and coastal structures, typhoon events, aeolian transport, and sea level rise, were discussed. Subsequently, adaptive protection measures, including beach nourishment, accompanied with groin system or multiple detached breakwaters were proposed to combat with beach erosion. The analysis presented in this study is helpful to understand the morphodynamics and to predict the future change of beaches. [ABSTRACT FROM AUTHOR]

This research is dedicated to examining downslope sediment transport on steep shorefaces. We present a model that incorporates nonlinear surface wave profiles, sediment movement thresholds, and slope effects, utilizing a set of semi-empirical formulas. The model quantitatively assesses the disparity between wave-augmented upslope transport and gravity-augmented downslope transport, and computes sediment transport rates using a single calibration coefficient. Validation of the model is carried out in the Fuji coast of Japan, where offshore wave conditions and seabed topography with a uniform grain size distribution serve as inputs. The computational outcomes reveal that sediment transport primarily occurs under high wave conditions, and downslope transport dominates on steep slopes. The calibration coefficient is determined through a comparison with observed data, demonstrating a strong agreement in the average annual sediment loss in the target area. Moreover, the model offers insights into the possible mechanism behind the existence of a transition area between the upper and lower shoreface, marked by an abrupt change in seabed slope. [ABSTRACT FROM AUTHOR]

Owing to its unique physical and socio-economic characteristics, the Saint Louis region stands out as one of the most susceptible areas in Senegal to the adverse impacts of coastal erosion. The dynamics of erosion in this region are significantly influenced by the Langue de Barbarie (LB), a sand spit formed at the mouth of the Senegal River. Initially, in 2003, a 4 m wide artificial breach was strategically introduced to mitigate flooding; however, sediment dynamics expanded it to 6 km by 2020, thereby affecting the entire region. This study delves into the coastline change of the LB, specifically divided into three zones (LB-1, LB-2, and LB-3), spanning the period from 1994 to 2042. Leveraging Geographic Information System (GIS) and remote sensing techniques, our investigation reveals that, prior to the breach's creation, the average dynamic coastline rates in zones LB-1, LB-2, and LB-3 were estimated at 4.4, 5.9, and 4.4 m/year, respectively. Subsequent to the breach, these rates shifted to −1.2, 8.4, and −2.7 m/year, with the most significant erosion observed alongshore of LB-3 at −6.6 m/year during the period 2002–2012. Projecting into 2032, LB-1 and LB-3 are anticipated to experience erosion rates of −11.5 and −26.8 m/year, respectively, while the LB-2 records an estimated accretion rate of 8.41 m/year. Eroded areas are expected to total 571,458 m2, while accumulated areas are expected to total 67,191 m2. By 2042, zones LB-1, LB-2, and LB-3 are expected to experience erosion rates of −23 and −53.6 m/year, resulting in the erosion of 1,021,963 m2 and the accumulation of 94,930 m2 with a dynamic rate of 168.2 m/year in zone LB-3. These results have significant implications for solving the urgent issue of coastal erosion in LB. [ABSTRACT FROM AUTHOR]

Climate change is increasingly affecting components of the terrestrial cryosphere with its adverse impacts in the Arctic regions of our planet are already well documented. In this context, it is regarded today as a key scientific priority to develop methodologies and operational tools that can assist towards advancing our monitoring capabilities and improving our decision-making competences in Arctic regions. In particular, the Arctic coasts are the focal point in this respect, due to their strong connection to the physical environment, society, and the economy in such areas. Geoinformation, namely Earth Observation (EO) and Geographical Information Systems (GISs), provide the way forward towards achieving this goal. The present review, which to our knowledge is the first of its kind, aims at delivering a critical consideration of the state-of-the-art approaches exploiting EO datasets and GIS for mapping the Arctic coasts properties. It also furnishes a reflective discussion on the scientific gaps and challenges that exist that require the attention of the scientific and wider community to allow exploitation of the full potential of EO/GIS technologies in this domain. As such, the present study also serves as a valuable contribution towards pinpointing directions for the design of effective policies and decision-making strategies that will promote environmental sustainability in the Arctic regions. [ABSTRACT FROM AUTHOR]

The Philippines has dynamically active coastal areas where sediment transport is a matter of concern due to its environmental implications, one of which is coastal erosion. Local studies have used seasonal beach profiling, shoreline tracing, and bathymetric analysis to provide relevant information on possible causes, trends, and adaptation strategies to address coastal erosion, but studies using numerical modelling of morphological dynamics are limited despite its capability to quantify different processes that is essential when an engineering intervention is necessary. This study uses numerical modelling in assessing coastal erosion and aims to model the hydrodynamics, waves, sediment transport and morphological dynamics of the study area using Delft3D. A 3-dimensional, coupled FLOW and WAVE model was set-up and calibrated to assess the transport of sediments and morphological dynamics in Ibajay, Aklan, one of the areas tagged as experiencing coastal erosion due to the presence of identifying physical features. The model was calibrated by comparing simulation results with measured time-series water level, bottom velocity, and wave parameters obtained from field surveys. Good agreement with measured parameters was observed after calibration, with root-mean-square-error of less than 10% of range of observed values at an observation point located 100 m off the coast at a depth of 8 m. The calibrated model was run for one year under prevailing (non-extreme) wind and wave conditions. Results showed two transport patterns caused by breaking of waves and strong currents near the lateral boundaries. It was determined that the shore is accreting with some erosion observed on the lateral boundaries caused by tidal asymmetry. Dry season months from November to April exhibited more active cross-shore transport due to intensifying of waves brought by the northeast monsoon while recovery of sand was observed during calmer conditions the rest of the year. [ABSTRACT FROM AUTHOR]

Globally, the rapid retreat of coastal cliffs poses a profound risk to property, transport infrastructure, and public safety. To quantify and compare cliff top and cliff face retreat and identify erosion processes, this study combines historical (1842–2000) maps and orthophotos with contemporary UAV surveys (2019–2023) to quantify cliff top and cliff face retreat along a 240 m wide coastal drumlin in Galway Bay, Ireland. Retreat rates for the cliff top and cliff face were calculated using 2D mapping and 3D modelling, respectively. Critically, the choice of method has a significant impact on calculated rates of cliff top retreat, with output from the 2D mapping approach (0.14 +/− 0.02 m yr−1) being double that of the 3D modelling approach (0.08 +/− 0.02 m year−1). The aperiodic development of a talus cone, which temporarily protects the cliff from storm waves, also influences estimates of cliff retreat. The repeat cycles of talus slope formation and removal in this high wave energy environment suggest that the drumlin scarp transitions between a periodically transport-limited and supply-limited system over short- and long-time periods, respectively, on the continuum of cliff types. These results warrant further research to identify and quantify the rates, patterns, drivers (marine and subaerial processes), and timing of cliff retreat in response to climate change. [ABSTRACT FROM AUTHOR]

Heritage sites in coastal areas are increasingly at risk from inundation hazards due to land subsidence, pluvial floods, coastal erosion, and sea-level rise. In this study, we evaluated the seven relatively well-preserved cultural heritage sites on the southwestern coast of Taiwan threatened by inundation risks resulting from current land subsidence, pluvial floods, coastal erosion, and future rising sea levels by 2050 and 2100. We applied a high-resolution hydrodynamic model to project coastal inundation zones caused by sea-level rise. Here, we show that of the seven most well-preserved cultural heritage sites in low-lying coastal areas of the southwestern coast of Taiwan, all seven are at risk from existing land subsidence, three from current coastal erosion, and six from the pluvial flooding. Regarding sea-level rise inundation risks, only one cultural heritage site is simulated to be threatened by 2050, even in the highest emission scenario. However, the one, two, and seven relatively well-preserved cultural heritage sites would be inundated by 2100 once sea-level rises of the lowest, medium, and highest emission scenarios are imposed on the coastal flood model. Our results provide a primary assessment of where adaptation is most imperatively needed and can support policymakers in steering local-scale research to devise appropriate adaptation strategies for each coastal heritage site in Taiwan. [ABSTRACT FROM AUTHOR]

The intensity of coastal erosion is a measure of the strength of erosion processes affecting coastal areas. Traditionally, assessments of coastal erosion intensity have relied on singular indices, such as the rate of shoreline retreat or erosion, often prioritizing higher rates over lower ones. This approach, however, lacks comprehensive consideration and scientific rigor. In this study, we adopt a more holistic approach by examining the Qionghai-Wanning coast on the eastern side of Hainan Island. We selected four indices that reflect local conditions and influence coastal erosion strength: Annual rate of shoreline change (T1), Beach annual down-cutting rate (T2), Beach slope (T3), Average particle size of the beach (T4). These indices were used to comprehensively evaluate the erosion intensity of the Qionghai-Wanning coast. The evaluation results categorized the study area into six grades: serious erosion (3.45%), strong erosion (6.90%), erosion (20.69%), micro erosion (44.38%), stabilization (20.69%), and accretion (3.45%). The findings indicate that, under the broader environmental trends of global warming and rising sea levels, most sandy coasts exhibit micro-erosion intensity. Areas experiencing strong and serious erosion are predominantly influenced by human activities, such as those occurring in promenade bays, artificial islands, and harbors. To further understand the relationship between these factors and erosion intensity, we employed the Spearman correlation coefficient method. The analysis revealed that the T1 and the T2 are the primary factors influencing coastal erosion intensity, with the T4 serving as a secondary factor. These factors collectively impact the force and energy absorption of the coast through wave and tidal actions, ultimately determining the intensity of coastal erosion. The multi-index assessment method for coastal erosion intensity demonstrated an accuracy of 82.75%, providing a scientific basis for the management, protection, and restoration of coastal areas.

In coastal erosion studies, the erosion and accretion index is a vital research tool for analyzing types of erosion and accretion. This index is primarily empirical or semi-empirical and is usually validated through tank experiments or open beach datasets, resulting in significant variation across different beach environments. In this study, 11 beach profiles of eight beaches measured along the Qiongzhou Strait in China, measured from 2018 to 2021, were analyzed to quantitatively determine coastal erosion or accretion by calculating each profile’s volume change per unit width. Additionally, sediment and wave data were used to calculate five erosion and accretion indices monthly to determine erosion and accretion conditions. These conditions were then compared with actual beach erosion and accretion data to evaluate the applicability of various discriminant indices. Furthermore, optimizing the threshold values of discriminant indices. The results show that: (1) Overall annual erosion and accretion are minimal, but seasonal variation is significant for beaches on both sides of the Qiongzhou Strait; (2) The five discriminant indices have some limitations in this study area, necessitating careful consideration when applying them to headland bay arc-shaped beaches with fetch-limited environments like the Qiongzhou Strait; (3) The selection of discriminant index parameters and their respective contribution degree of each parameter affects the formula’s applicability, with two-parameter formulas proving superior to the three-parameter formula in the study area; (4) Beach environmental factors, particularly those influenced by headlands and fetch-limited environments, impact the indices’ applicability; (5) Increasing the threshold value to a certain extent can improve the formula’s applicability.