Search Results (237)

Land–sea segmentation is a fundamental task in remote sensing image analysis, and plays a vital role in dynamic coastline monitoring. The complex morphology and blurred boundaries of coastlines in remote sensing imagery make fast and accurate segmentation challenging. Recent deep learning approaches lack the ability to model spatial continuity effectively, thereby limiting a comprehensive understanding of coastline features in remote sensing imagery. To address this issue, we have developed VMMT-Net, a novel dual-branch semantic segmentation framework. By constructing a parallel heterogeneous dual-branch encoder, VMMT-Net integrates the complementary strengths of the Mix Transformer and the Visual State Space Model, enabling comprehensive modeling of local details, global semantics, and spatial continuity. We design a Cross-Branch Fusion Module to facilitate deep feature interaction and collaborative representation across branches, and implement a customized decoder module that enhances the integration of multiscale features and improves boundary refinement of coastlines. Extensive experiments conducted on two benchmark remote sensing datasets, GF-HNCD and BSD, demonstrate that the proposed VMMT-Net outperforms existing state-of-the-art methods in both quantitative metrics and visual quality. Specifically, the model achieves mean F1-scores of 98.48% (GF-HNCD) and 98.53% (BSD) and mean intersection-over-union values of 97.02% (GF-HNCD) and 97.11% (BSD). The model maintains reasonable computational complexity, with only 28.24 M parameters and 25.21 GFLOPs, striking a favorable balance between accuracy and efficiency. These results indicate the strong generalization ability and practical applicability of VMMT-Net in real-world remote sensing segmentation tasks. Full article

Mangrove ecosystems are crucial coastal habitats that support life and regulate the Earth’s atmosphere. However, these ecosystems face prominent threats due to anthropogenic activities and environmental constraints. For instance, the Saudi Arabian coast is particularly vulnerable to species extinction and biodiversity loss due to the fragility of the ecosystem; this highlights the need to understand the spatial and temporal dynamics of mangrove forests in desert environments. Hence, this is the first national study to quantify mangrove forests and analyze at-risk zone-based land use along Saudi Arabian coasts over 40 years. Thus, the primary contents of this research were (1) to produce a new long-term dataset covering the entire Saudi coastline, (2) to identify the patterns, analyze the trends, and quantify the change of mangrove areas, and (3) to determine vulnerability zoning of mangrove area-based land use and transportation networks. This study used Landsat satellite imagery via Google Earth Engine for national-scale mangrove mapping of Saudi Arabia between 1985 and 2024. Visible and infrared bands and seven spectral indices were employed as input features for the random forest classifier. The two classes used were mangrove and non-mangrove; the latter class included non-mangrove land-use and land-cover areas. Then, the study employed the output mangrove mapping to delineate vulnerable mangrove forest-based land use. The overall results showed a substantial increase in mangrove areas, ranging from 27.74 to 59.31 km² in the Red Sea and from 1.05 to 8.65 km² in the Arabian Gulf between 1985 and 2024, respectively. However, within this decadal trend, there were noticeable periods of decline. The spatial coverage of mangroves was larger on Saudi Arabia’s western coasts, especially the southwestern coasts, than on its eastern coasts. The overall accuracy, conducted annually, ranged between 91.00% and 98.50%. The results also show that expanding land uses and transportation networks within at-risk zones of mangrove forests may have a high potential effect. This study aimed to benefit the government, conservation agencies, coastal planners, and policymakers concerned with the preservation of mangrove habitats. Full article

The coastline of the Yellow River Delta in China has experienced significant dynamic changes due to both natural and human activities. Investigating its coastal dynamics and understanding the equilibrium with riverine runoff and sediment discharge is crucial for ecological balance and sustainable development in the region. In this study, a coastline extraction algorithm was developed by integrating water index and dynamic frequency thresholds based on the Google Earth Engine platform. Long-term optical remote sensing datasets from Landsat (1988–2016) and Sentinel-2 (2017–2023) were utilized. The End Point Rate (EPR) and Linear Regression Rate (LRR) methods were employed to quantify coastline changes, and the relationship between coastal evolution and runoff–sediment dynamics was investigated. The results revealed the following: (1) The coastline of the Yellow River Delta exhibits pronounced spatiotemporal variability. From 1988 to 2023, the Diaokou estuary recorded the lowest EPR and LRR values (−206.05 m/a and −248.33 m/a, respectively), whereas the Beicha estuary recorded the highest values (317.54 m/a and 374.14 m/a, respectively). (2) The cumulative land area change displayed a fluctuating pattern, characterized by a general trend of increase–decrease–increase, indicating a gradual progression toward dynamic equilibrium. The Diaokou estuary has been predominantly erosional, while the Qingshuigou estuary experienced deposition prior to 1996, followed by subsequent erosion. In contrast, the land area of the Beicha estuary has continued to increase since 1997. (3) Deltaic progradation has been primarily governed by runoff–sediment dynamics. Coastline advancement has occurred along active river channels as a result of sediment deposition, whereas former river mouths have retreated landward due to insufficient fluvial sediment input. In the Beicha estuary, increased land area has exhibited a strong positive correlation with annual sedimentary influx. The critical sediment discharge required to maintain equilibrium has been estimated at 79 million t/a for the Beicha estuary and 107 million t/a for the entire deltaic region. These findings provide a scientific foundation for sustainable sediment management, coastal restoration, and integrated land–water planning. This study supports sustainable coastal management, informs policymaking, and enhances ecosystem resilience. Full article

Climate change poses substantial threats to natural ecosystems and human livelihoods, particularly in coastal regions, by intensifying coastal erosion. This process leads to land loss, infrastructure damage, and habitat destruction while amplifying challenges such as sea-level rise, flooding, desertification, and salinization. In Vietnam’s Red River Delta (RRD), the dynamic interplay between erosion and accretion presents a highly complex challenge, necessitating effective risk assessment and management to safeguard communities and resources. Using the principles of natural disaster risk assessment and comprehensive analysis, this study develops a coastal erosion risk assessment framework incorporating hazard, exposure, and vulnerability dimensions. The framework integrates 17 indicators, including human activities, socioeconomic factors, shoreline type, and vegetation cover, with indicator weights determined through expert evaluation and the analytic hierarchy process. The application of this framework reveals that coastal erosion risk in the RRD is relatively high, with greater risk concentrated in the central and northern segments of the coastline compared to the flanking areas. This framework offers valuable insights for coastal erosion prevention, mitigation strategies, and the optimization of coastal spatial planning. The application of coastal erosion risk assessment methods provides a relatively complete foundation for developing comprehensive prevention and adaptation solutions in the future. Through the system of parameters and corresponding weights, it provides an overview of potential responses to future impacts while identifying current high-risk zones specifically and accurately, thereby assessing the importance of each parameter on that impact. Based on specific analysis of assessment results, a reasonable resource use and management policy can be developed to minimize related natural disasters. Therefore, two main groups of solutions proposed under the “Protection—Adaptation” strategy are proposed to prevent natural disasters, minimize risks and sustainably develop the coastal area of the RRD. Full article

This article explores Greco-Roman mythology through the lens of ecocriticism, focusing on how sacred landscapes and natural elements were imagined as animate, divine, and morally instructive forces. In ancient Mediterranean cultures, nature was not merely a passive setting for human action but a dynamic presence—rivers that judged, groves that punished, and mountains that sheltered or revealed. Texts such as Ovid’s Metamorphoses, Virgil’s Georgics, and Homer’s epics present nature as both sacred and sentient, often intervening in human affairs through transformation, vengeance, or protection. Forests, springs, and coastlines functioned as thresholds between human and divine, civilization and wilderness, mortal and eternal. By analyzing these representations, this article reveals a rich tradition in which nature teaches, punishes, guides, and transforms, long before ecological consciousness became a formalized discipline. Drawing connections between classical literary landscapes and contemporary environmental concerns, the article argues that myth can inform today’s ecological imagination, offering an alternative to extractive, anthropocentric paradigms. Recovering the reverence and narrative agency once granted to nature in classical thought may help us rethink our ethical relationship with the environment in the age of climate crisis. Full article

Climate change places urban coastlines at significant risk from rising sea levels and increasing storm intensity and frequency. This paper uses Red Hook, Brooklyn, NY as a case study to identify knowledge gaps in current climate resilience efforts across low-lying, post-industrial landscapes in coastal cities. Through an analysis of the short- and long-term effects of Superstorm Sandy (29 October 2012), current city planning efforts, and resulting architectural adaptations, this paper uncovers the shortcomings and possible maladaptive planning in Red Hook and New York City’s overall coastal resilience efforts. As a response to these findings, a new framing for future resilience efforts is proposed through speculative student design proposals and international case studies, applying a more dynamic understanding of climate resilience. These proposals envision a future climate-resilient, heterogeneous model for post-industrial coastal neighborhoods, transitioning to urban landscapes that embrace their shifting shorelines. This paper’s conclusion argues that effective coastal resilience requires strategies that work at multiple scales with shifting water–land boundaries rather than against them. Full article

As the first marine economic zone, the coastal zone is a complex and active ecosystem, serving as an important resource breeding area. However, during the process of economic development, coastal zone resources have been severely exploited, leading to fragile ecology and frequent natural disasters. Therefore, it is imperative to analyze coastline changes and their correlation with coastal ecological space. Utilizing long-time series high-resolution remote sensing images, Google Earth images, and key sea area unmanned aerial vehicle (UAV) remote sensing monitoring data, this study selected the coastal zone of Ningbo City as the research area. Remote sensing interpretation mark databases for coastline and typical coastal ecological space were established. Coastline extraction was completed based on the visual discrimination method. With the help of the Modified Normalized Difference Water Index (MNDWI), Normalized Difference Vegetation Index (NDVI) and maximum likelihood classification, a hierarchical classification discrimination process combined with a visual discrimination method was constructed to extract long-time series coastal ecological space information. The changes and the linkage relationship between the coastlines and coastal ecological spaces were analyzed. The results show that the extraction accuracy of ground objects based on the hierarchical classification process is high, and the verification effect is improved with the help of UAV remote sensing monitoring. Through long-time sequence change monitoring, it was found that the change in coastline traffic and transportation is significant. Changes in ecological spaces, such as industrial zones, urban construction, agricultural flood wetlands and irrigation land, dominated the change in artificial shorelines, while the change in Spartina alterniflora dominated the change in biological coastlines. The change in ecological space far away from the coastline on both the land and sea sides has little influence on the coastline. The research shows that the correlation analysis between coastline and coastal ecological space provides a new perspective for coastal zone research. In the future, it can provide technical support for coastal zone protection, dynamic supervision, administration, and scientific research. Full article

This study combines field and laboratory analyses from seven shallow wells (ZK1 to ZK7) positioned perpendicular to the coastline to investigate groundwater discharge and dynamics in the coastal unconfined aquifer of the intertidal zone at Yazhou Bay, Sanya, Hainan Province. The research highlights spatial variations in N₂O concentration, temperature, electrical conductivity (EC), pH, and the distribution of CFCs and CCl₄ in shallow groundwater, utilizing samples from wells ZK1 to ZK7 and seawater collected near ZK1. Key findings indicate that groundwater temperature decreases toward the ocean, while EC exhibits a stepwise increase from land to sea, with a sharp transition near ZK3 marking the freshwater–saltwater mixing zone. pH values are lowest in ZK3 and ZK4, gradually rising both inland and seaward. N₂O concentrations in the shallow wells (ZK1–ZK7) are divided into two distinct groups: higher concentrations (9.69–57.77 nmol/kg) in ZK5–ZK7 and lower concentrations (6.63–23.03 nmol/kg) in ZK1–ZK4. Wells ZK3 and ZK4 show minimal variation in CFC-11 and CFC-113 concentrations, suggesting they represent a transition zone that likely delineates groundwater flow paths. In contrast, significant concentration differences in wells ZK5–ZK7 (north) and ZK1–ZK2 (south) reflect the influence of aquifer structure variability, recharge sources, and local hydrogeochemical conditions. CFC-12 concentrations exhibit a clear freshwater–saltwater mixing gradient between ZK3 and ZK1, with higher concentrations in freshwater-dominated areas (ZK3–ZK7) and lower concentrations near seawater (ZK1). CCl₄ concentrations at ZK7 and ZK3 differ markedly from other wells, indicating unique hydrogeochemical conditions or localized anthropogenic influences. A model for the formation of upper saline plumes (USP) under tidal forcing at the low tidal line was established previously. Here, we establish a new model that accounts for the absence of USP driven by hydrological processes influenced by artificial sandy beach topography, and a fresh groundwater wedge is identified, which can serve as a significant fast-flow pathway for terrestrial water and nutrients to the ocean. Full article

Lateral cavities along coastlines strongly influence sedimentary morphology and ecological processes by modifying local flow dynamics. This study employed high-resolution large-eddy simulation to investigate flow structures and momentum exchange mechanisms in a semi-circular lateral cavity driven by longshore currents. Model validation against experimental data confirmed the LES’s capability to capture both recirculating flow and turbulent structures accurately. The impact of Reynolds number was examined across three cases ($Re$ = 12,000, 17,000, and 22,000). From $Re$ = 12,000 to 17,000, a significant upstream shift of the primary vortex core occurred, accompanied by stronger shear layer turbulence and intensified secondary vortices. Between $Re$ = 17,000 and 22,000, the flow features stabilized, indicating a transition toward quasi-equilibrium. These changes enhanced vertical momentum transfer and turbulence production within the cavity. Spectral analysis revealed dominant KH frequencies governing periodic momentum exchange and indicating a transition from viscosity-damped upstream turbulence to fully developed shedding downstream. Full article

The study assesses coastal evolution and the vulnerability of archaeological sites in Southeastern Crete. Shoreline dynamics since the 1940s were examined through the interpretation of high-resolution aerial photographs and satellite images. A set of climatic variables, as well as data on geomorphological and geological factors obtained from fieldwork, images interpretation, archives, and open-source datasets, were analysed. The influence of these variables on coastal dynamics was evaluated using regression analysis, correlating their spatial distribution with rates of shoreline retreat/advance. Based on this, variables for the Coastal Vulnerability Index (CVI) calculation were selected, and the weighting for the weighted CVI (CVI_w) was determined. The classical CVI identified 13.7% of the study area’s coastline as having very high vulnerability to coastal hazards, 15.5% as highly vulnerable. In the case of CVI_w, 17.5% of the coasts of the area were classified as having very high level of vulnerability, 39.6%—as highly vulnerable. Both approaches, the CVI and the weighted CVI, highlighted the most vulnerable areas in the north, east, and southeast of Koufonisi Island, as well as the north and east of Chrisi Island. The least vulnerable areas include the wide beaches in enclosed bays, such as Gra Lygia, Ierapetra, and Ferma, along with rocky capes east of Ierapetra. Among the five archaeological sites examined, two (Lefki Roman Town and Stomio Roman Villa) fall within zones of high or very high coastal vulnerability. This study provides the first in-depth analysis of coastal dynamics and vulnerability of Southeastern Crete, a region with significant cultural heritage yet previously under-researched. Full article

River mouths are important indicators and mediators of interactions between rivers and the sea that mark the dispersal point for catchment-based stressors and subsidies. Satellite remote sensing data products and algorithms present many new possibilities for monitoring these dynamic and often inaccessible environments. In this study, we describe a national-scale comparative framework based on proximity to river mouths and show its application to the monitoring of coastal ecosystem health in Aotearoa New Zealand. We present results from light attenuation coefficient (K_d) analyses used to develop the framework considering data products of differing resolution and the effects of coastline geometries which might obscure the influence of catchment-derived stressors. Ten-year (2013–2022) K_d values from the highest-resolution product (500 m) showed significant differences (p < 0.01) in successively larger radii (1–20 km) despite the confounding influence of adjacent river mouths. Smaller radii returned a high variability that dropped markedly > 5 km. Tests of a 10 km radius showed that coastline geometry had a significant influence on K_d (p < 0.001), which is also likely for other water quality indicators. An analytical approach stratified by coastline geometry showed significant effects of stream order on open (p < 0.01) but not enclosed coasts, differences between marine bioregions (p < 0.05), and a degradation trend in the 90th percentile of K_d on enclosed coasts, which is indicative of extreme events associated with catchment erosion or sediment resuspension. We highlight applications of the framework to explore trends across many other meaningful scales (e.g., jurisdictions and ecosystem types) in addition to tracking changes at individual river mouths. Full article

Water and sediment fluxes into the sea are the basis for the stability of the ecological pattern of the Yellow River Delta (YRD). As a Ramsar wetland of international importance, the YRD is facing the huge ecological risk of land degradation due to changes in water–sediment fluxes into the sea. In this study, we investigated the spatiotemporal dynamics of the coastline and subaerial delta using annual remote sensing images and revealed more detailed and clear relationships between water–sediment fluxes into the sea and the YRD evolution, including the whole delta and its subregions (e.g., the Qingshuigou and Diaokou regions) from 1976 to 2022. Our results showed that the mean yearly water and sediment fluxes during the study period amounted to 210.50 × 10⁸ m³ yr⁻¹ and 367.81 Mt yr⁻¹, respectively. There was an abrupt change in water and sediment fluxes into the sea in 1999, and both decreased significantly from 1976 to 1999, whereas the water discharge has significantly increased and the sediment flux has stabilized since around 2000. The delta area evolutions of the whole YRD and the Qingshuigou region can be characterized by three stages: a rapid growth stage (1976–1993), a rapid retreat stage (1993–2002), and a gradual recovery stage (2002–2022). The area in the Diaokou region displayed a continuous decreasing trend from 1976 to 2022. The regression analysis indicated that the relationships between cumulative sediment flux and cumulative land accretion area presented spatiotemporal differentiation. The cumulative land accretion area increased with the cumulative sediment flux in the whole YRD and its subregions from 1976 to 1992, decreased with the cumulative sediment flux in the YRD from 1993 to 2002, except for the northeast of Qingshuigou, and then expanded with the cumulative sediment flux in the YRD from 2003 to 2022, except for the southeast of Qingshuigou. Full article

In historical regional cropland reconstruction in floodplains and delta areas, changes in the river system and the historical distribution of settlements are important to the spatial–temporal dynamic process of historical land reclamation. This paper takes the Yellow River Delta as the research area, combines historical data with field investigation, and analyzes the influence of river system change and delta formation on settlement establishment and land reclamation. The results revealed the following. (1) The development timing of the Yellow River determines the order of deposited land by old river courses and the settlement or resettlement process of the village. Since 1855, approximately 90% of new villages have been located within the 1–5 km buffer of the Yellow River channels. Two peak tides for village establishment along the Yellow River corresponded to the fluvial periods and the 20 ± 10 yr after the river silted out. It took over 100 years for the cultivation range to advance 5 km from the coastline of 1820 to the sea for the lengthy desalination and subsequent freshwater-driven dilution of the newly deposited land. (2) It is necessary to introduce the locations of the settlements, distance from the river courses, and coastline change to the cropland distribution model by setting parameters for different buffer zone distances. This paper provides data and theoretical parameters for cropland construction in the Yellow River Delta suitable for the floodplains and delta areas. The relevant findings can provide valuable references for land use policy formulation, agricultural development planning, and management practices in delta regions. Full article

This study investigates the influence of wave-climate datasets derived from in situ measurements and reanalysis models on predictive modelling accuracy for coastline evolution, focusing on the IJmuiden coastal stretch in The Netherlands. By analyzing wave parameters, sediment dynamics, and nourishment interventions, the research evaluates the performance of a numerical model in simulating shoreline changes over a 40-year period. Using the LTC (Long-Term Configuration) model, scenarios incorporating artificial sand nourishment volumes of 200,000 m³/year and 250,000 m³/year were tested against conditions without nourishment. The results highlighted the critical role of significant wave height, direction, and dataset variability in sediment accretion and erosion patterns. Datasets from in situ measurements (Measured-YM6) and reanalysis sources (ERA5, AENWS-WPR, and AENWS-WPR North) demonstrate variable performance, with ERA5 proving to be the most reliable under both nourished and non-nourished scenarios. The findings emphasize the importance of integrating high-resolution wave datasets into numerical models to improve predictions, optimize nourishment strategies, and enhance coastal resilience against erosion. The study underscores the necessity of nourishment interventions to mitigate sediment loss, stabilize shorelines, and support sustainable coastal-management practices in the face of climate change. Full article

This study examines the relative sea-level changes during the Upper Holocene period along the south coastline of Cyprus through the investigation of beachrock formations and their impact on archaeological sites. Beachrock, as a natural indicator of past relative sea levels, provides valuable insights into the dynamic interplay between sea-level fluctuations and human settlements. The research integrates field observations, mineralogical and geochemical analysis, geochronological studies, and archaeological data to reconstruct past sea-level variations and their implications for coastal archaeological sites. The results reveal significant fluctuations in relative sea levels during the Upper Holocene, influencing the development and occupation of coastal archaeological sites. By elucidating the complex relationship between sea-level changes and human activity, this study contributes to our understanding of past coastal environments and their socio-cultural dynamics. Moreover, it underscores the importance of considering geological factors in archaeological interpretations and coastal management strategies in the face of contemporary sea-level rise. Full article