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Coastal waters are currently receiving anthropogenic impacts from the mainland that caused the natural conditions to change to higher nutrient content. This study was conducted to examine the spatial and temporal dynamics of trophic status and how zone location and rainfall category affect the distribution of trophic status. Water quality data were collected for 6 months with different rainfall intensities at 16 observation stations. Trophic status was determined using the TRIX index which combines biological, physical, and chemical water variables. Rainfall had no significant effect on the TRIX index with a p-value of 0.223 (> 0.05), but the distance from the land had a significant effect with a p-value of (< 2e-16). In coastal waters in the 1st zone, the average TRIX value was 5.93 ± 0.23 (high trophic status/eutrophy that tends to be very high/hypertrophy), in the 2nd zone was 5.49 ± 0.21 (high trophic status/moderate trophy), in the 3rd zone was 5.23 ± 0.25 (high trophic status/eutrophy that is slightly low) and in the 4th zone was 4.47 ± 0.47 (moderate trophic status/mesotrophy). Based on PCA analysis and correlation for water quality data, Index TRIX had a strong positive correlation with phosphate (0.92), TSS (0.91), chlorophyll-a (0.089), temperature (0.88), nitrate (0.83), and moderate positive correlation with turbidity (0.68). In addition, the TRIX index had a strong negative correlation with salinity (-0.85), a moderate negative correlation with TDS (-0.77) and DO (-0.62), and a weak correlation with pH (-0.09). There has been eutrophication in coastal areas, especially in the near shoreline zone and tends to decrease at more distant locations. It is necessary to manage anthropogenic waste based on quality standards to ensure that coastal waters are healthy and support sustainable ecosystems. [ABSTRACT FROM AUTHOR]

Despite growing recognition of nature's impact on mental health, its specific effects on adolescents remain unclear. This gap hinders effective strategies for youth well-being in a world facing increasing environmental pressures. This study directly investigates the connections between coastal environments and subjective well-being in adolescents. We explore how interactions with coastal landscapes and associated cultural ecosystem services contribute to both personal and social dimensions of well-being in a sample of 202 adolescents (16 and 17 years old) from Sardinia, Italy. Our findings reveal a beneficial impact of coastal experiences, promoting positive affect, social integration, and physiological well-being. However, human pressures on these environments can lead to negative affect, while fostering a sense of social contribution. This research highlights the complex interplay between coastal environments, human impacts, and teenagers' well-being. Understanding these links empowers planners to craft coastal management strategies that balance adolescents' well-being with the long-term sustainability of coastal regions. [ABSTRACT FROM AUTHOR]

ABSTRACT The yellowtail catfish (Pangasius pangasius) population in Bangladesh is facing imminent threats that led to endangered status. We used conventional scientific knowledge (CSK) and local ecological knowledge (LEK) of fishers (n = 155) to identify nursery grounds and spawning seasons of yellowtail catfish in the Meghna river estuary. Nineteen nursery grounds were pinpointed using fishers' LEK (confluence/influent zone, current, depth, catch data, and turbidity) and later validated by CPUE data. The peak spawning season was identified in July–September based on GSI (gonadosomatic index) and LEK (58.06% of fishers identified the spawning season). Fecundity (810,980 ± 455,679) and condition factor (0.94–1.52) were quantified with CSK. Using CSK and LEK to delineate nursery grounds and spawning season underscores the value of LEK as a tool for fish population management that deserves policy recommendation and wider application. [ABSTRACT FROM AUTHOR]

The handling of beached cetacean carcasses requires social, legal, financial, ecological and logistical considerations. However, limited research on the topic hinders informed decision-making. A large humpback whale carcass that washed ashore at a South African marine protected area (MPA) provided an opportunity to gain insight into tourists' perspectives on carcass management within a national park and MPA setting. Eighty tourists were interviewed, and a thematic analysis approach was adopted to identify key themes and quantify the responses. Chi-square tests of independence were used to determine (i) whether the respondents' views on cetacean carcass management were dependent on their knowledge of the site's MPA designation, and (ii) whether the provision of contextual information would influence the respondents' perceptions. Tourists had mixed responses to whale carcass management, with half the respondents indicating that the carcass should be left to decompose naturally. Viewpoints were significantly influenced when context and information on the decision-making process were provided, with more respondents stating that no management intervention should be necessary. We propose a simple flow-diagram as a decision-support tool, which, in combination with spatial zonation maps to identify applicable management options, will help guide decision-making for management authorities. Inclusivity, transparency and consultation with experienced role-players from multiple agencies will provide legitimacy to the final management decisions. [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 Fraser River Delta (FRD) is a large sedimentary system and home to Metro Vancouver, situated within the unceded territories of several First Nations. This review provides an overview of the geological evolution of the FRD, connecting hydrodynamic processes with sedimentary deposits across its diverse environments, from the river to the delta slope. The study emphasizes the implications of sedimentation and delta evolution for natural hazards and coastal/delta management, pinpointing knowledge gaps. Comprising four main zones—river, delta plain, tidal flats, and delta slope—the FRD is subject to several natural hazards, including subsidence, flooding, earthquakes, liquefaction, and tsunamis. The delta plain, bordering the Fraser River's distributary channels, hosts tidal marshes and flats, including both active and abandoned areas. Active tidal flats like Roberts Bank and Sturgeon Bank receive sediment directly from the Fraser River, while abandoned tidal flats, like those at Boundary Bay and Mud Bay, no longer receive sediment. The tidal flats transition into the delta slope, characterized by sand in the south and mud in the north of the Main Channel. The FRD's susceptibility to hazards necessitates protective measures, with approximately 250 km of dykes shielding the delta plain from river floods and storm surges. Subsidence amplifies the impact of rising sea levels. Earthquakes in the region can induce tsunamis, submarine slope failures, and liquefaction of delta sediments, emphasizing the importance of incorporating sedimentation patterns and delta evolution into management strategies for sustainable urban development, habitat restoration, and coastal defence initiatives. [ABSTRACT FROM AUTHOR]

Kelp forests dominate the western and southwestern coastlines of southern Africa. This expansive ecosystem spreads over two very different ecoregions that are of particular interest to researchers due to the complexities of their physical environment. The mid-to-late 1900s saw a proliferation in pioneering research on southern African kelp forests. Since this period (1970–1989), researchers have published comparatively few seminal studies concerning kelp forest ecology and biological functioning. In light of this deficit, this review synthesised pre-existing research on southern African kelp forests, and highlighted key gaps in the research landscape to spark interest and facilitate new studies. Among several others, key research gaps uncovered by this review include kelp carbon sequestration potential and possible contributions to the blue bioeconomy; deeper exploration into the biological functioning and ecological roles of Macrocysis pyrifera and Ecklonia radiata populations in southern Africa; and the impacts of a changing physical environment on these kelp forests. In light of our rapidly changing climate, filling these gaps will be essential in informing conversations around coastal and marine management decisions and policy. [ABSTRACT FROM AUTHOR]

Dune vegetation mediates dune-building through trapping wind-blown sand and reduces dune erosion by attenuating wave energy via above- and belowground biomass. Despite the role of vegetation in dune functions, the amount and distribution of biomass within a dune remains poorly quantified due to a lack of ample data. Our objectives were to determine the effects of management history and elevation on (1) dune belowground biotic structure and aboveground community composition and (2) to determine best predictors of belowground biomass. We sampled belowground biomass and sedimentology across the dune profile at sites in the Outer Banks, North Carolina, USA. Dunes were classified as either unmanaged (no anthropogenic interventions) or managed (sand fencing, vegetation planting, dune construction). Living belowground biomass was higher in unmanaged dunes and decreased with depth. Non-living belowground biomass was 50% higher than living biomass and with greater abundance in unmanaged dunes. Elevation was a significant covariate of living and non-living belowground biomass, vegetative cover and species richness. Plant community composition varied less in managed dunes and differed significantly from unmanaged dunes. Vegetative cover, species richness, elevation, sedimentology and management history were predictors of belowground biomass. These results underscore the influence of management and geomorphology on dune plant communities, which may influence erosion resistance. [ABSTRACT FROM AUTHOR]

Since the 1970s oil boom, nations surrounding the Arabian Gulf have witnessed rapid coastal urbanization, which accelerated in the early 2000s with the emergence of large-scale coastal 'mega-projects' designed to accommodate growing populations, attract international investments, and promote tourism. This development surge has had profound environmental impacts, including significant habitat modification, land use and land cover (LULC) change, and increased environmental pressure. Remote sensing (RS) technologies have become indispensable tools for monitoring these changes, offering costeffective and non-intrusive methods to map and assess coastal zones. However, RS applications across the Arabian Gulf have been spatially limited, often focusing narrowly on specific cities or habitats while neglecting the broader geographical and coastal dimensions of urbanization. This study addresses this gap by conducting a systematic review of peer-reviewed RS literature from 1971 to 2022, covering the coastal regions of the eight nations bordering the Arabian Gulf. A total of 186 publications were categorized into three focal areas: 1) coastal urbanization and LULC, 2) coastal and marine habitats, and 3) environmental pressures and state changes. The results reveal a significant increase in RS studies in recent years, with around two-thirds of the publications (64.3%) appearing between 2016 and 2022. Studies predominantly focused on environmental pressures and state changes (35%), followed by habitat modification (27%), and coastal urbanization (20%). Geographically, RS research primarily concentrated on the coasts of the southern Gulf (UAE and Qatar) and western Gulf (Bahrain and Saudi Arabia), where major urban centers are located, while the northern Gulf (Kuwait and Iraq) and Iranian coast have been less studied. The systematic review highlights the need for integrated RS and GIS-based monitoring systems that combine different sources of RS data and in situ measurements to evaluate the Gulf as a unified system. Expanding spatial coverage, enhancing temporal analysis, and fostering regional collaboration are necessary to improve the understanding and management of coastal urbanization and environmental changes in the Arabian Gulf. This approach will more effectively inform decision-makers, and support more sustainable coastal management and long-term environmental resilience in the region. [ABSTRACT FROM AUTHOR]

Soil erosion in coastal areas, driven by global change and human activity, poses a significant threat to ecological and economic stability. This research investigates water erosion in the southeast of the Ría de Arosa (Pontevedra, Spain), utilizing the Revised Universal Soil Loss Equation model and Geographic Information System technologies. Key factors analyzed include rainfall erosivity, soil erodibility, topography, land cover, and conservation practices. High-resolution maps (1 × 1 m pixels) identified areas at high risk of erosion. Vulnerable zones, such as coastal cliffs and vineyards, show severe erosion rates exceeding 50 t/ha/year (>5 mm/year), with the most extreme zones reaching up to 200 t/ha/year (>200 mm/year). These results emphasize that intervention could be required or recommended. Suggested measures include reforestation, effective agricultural land management, or the implementation of vegetative barriers to reduce erosion. These areas, characterized by steep slopes and sparse vegetation, are particularly susceptible to soil loss, necessitating specific conservation efforts. The results underscore the need for sustainable coastal management practices and preventive strategies to protect this vulnerable coastal zone. Implementing these measures is crucial to mitigating the impacts of soil erosion, preserving natural resources, and ensuring long-term ecological and economic resilience in the region. [ABSTRACT FROM AUTHOR]

Long-term declines in coastal water quality and sedimentation can affect the restoration success of ecosystems such as seagrass and shellfish reefs. Resnagging coastal seascapes offers a potential alternative restoration method that is not reliant on abiotic conditions and which may enhance degraded landscapes for fish and fisheries. While common in freshwater ecosystems, such interventions are unusual for coastal seascapes despite log snags supporting significant benefits for coastal fish. In this study, we identify the spatial (e.g. seascape connectivity), habitat condition (e.g. log snag complexity and food availability) and water quality variables that best explain variation in fish assemblages on log snags to help prioritise the placement and design of resnagging efforts in estuaries. We surveyed fish assemblages on log snags using underwater videography at 363 sites across 13 estuaries in southeast Queensland, Australia, over 3 years. Sites less than 10,000 m from the estuary mouth, more than 2500 m from urban structures and located in water depths of < 3 m harboured more diverse fish assemblages. Sites less than 10,000 m from the estuary mouth with lower (< 25%) algae cover harboured greater total fish abundance and harvested fish abundance. Similar trends were found for the abundance of individuals from key functional groups, although these trends were mediated by other seascape contexts (e.g. the area of natural habitat) and water quality variables (e.g. chlorophyll-a concentration and dissolved oxygen saturation). Our results indicate that log snag placement in estuaries for benefits to fish and fisheries can be maximised if sites are planned strategically. [ABSTRACT FROM AUTHOR]

Abstract Dune vegetation mediates dune-building through trapping wind-blown sand and reduces dune erosion by attenuating wave energy via above- and belowground biomass. Despite the role of vegetation in dune functions, the amount and distribution of biomass within a dune remains poorly quantified due to a lack of ample data. Our objectives were to determine the effects of management history and elevation on (1) dune belowground biotic structure and aboveground community composition and (2) to determine best predictors of belowground biomass. We sampled belowground biomass and sedimentology across the dune profile at sites in the Outer Banks, North Carolina, USA. Dunes were classified as either unmanaged (no anthropogenic interventions) or managed (sand fencing, vegetation planting, dune construction). Living belowground biomass was higher in unmanaged dunes and decreased with depth. Non-living belowground biomass was 50% higher than living biomass and with greater abundance in unmanaged dunes. Elevation was a significant covariate of living and non-living belowground biomass, vegetative cover and species richness. Plant community composition varied less in managed dunes and differed significantly from unmanaged dunes. Vegetative cover, species richness, elevation, sedimentology and management history were predictors of belowground biomass. These results underscore the influence of management and geomorphology on dune plant communities, which may influence erosion resistance.

Seawater intrusion (SWI) is a concern for coastline-saturated aquifers because it increases salinity, which contaminates and degrades groundwater quality. Rising sea levels and other natural processes, as well as anthropogenic activities such as overpumping, are the causes of intrusion. Because these experiments are the most reliable methods for study, this study focused on the experimental investigation of SWI in a hypothetical stratified aquifer with parallel and perpendicular stratification and a sloping beach boundary. Stratified media were formed by stacking layers in parallel and perpendicular layers in different combinations. Sensitivity analysis was performed with 10-, 20-, and 30-cm gaps for interactions with 4-layer formations with height to toe length expanding from 0.12 to 2.33. High-resolution images were captured at specified intervals and demarcated for a clear visualization of intrusion. A homogenous base case was used to evaluate the feasibility of the proposed method and the results were compared with those of a sandbox apparatus and found to be consistent in terms of the shape of the wedge and the toe length. The height of the intrusion ranges from 28.3 to 32.2 cm. The intrusion was fast and accurate due to the higher permeability of the material. It was concluded that the toe length–height ratio varies from 0.43 to 7.0. For materials with lower permeabilities, this ratio is small because the intrusion is slow but steady in both directions; however, for materials with higher permeabilities, this ratio corresponds to a higher value. The intrusion is restricted to the individual layer until it encounters an impervious layer and follows a proportional pattern with an increasing area of intrusion as the opening area increases. Practical Applications: This study focused on determining the intrusion behavior in coastal aquifers with monotonically increasing permeability under a layered stratification condition and subjected to the application of inclined boundaries. The study revealed that the use of a glass box apparatus with an inclined ocean–aquifer boundary is the best practical approach for studying intrusion. The occurrence of intrusion due to density differences and heterogeneity represents a case of passive seawater intrusion. The heterogeneity of the aquifer varies at the regional scale; thus, the results obtained from this study may be applied to real-world scenarios by implementing upscaling, temporal dynamics, heterogeneity, and desired boundary conditions. To quantify the intrusion in parallel stratification, a ratio of toe length to height of the intrusion is devised, which is the best approach to follow. The intrusion in the parallel configuration directly depends on the face of the inclined formation subjected to seawater, which forms a parabolic profile, while for the perpendicular configuration, the potential to intrude decreases with each layer as the intrusion is subjected to one layer at a time, initially leading to a parabolic profile that changes to linear in subsequent layers. [ABSTRACT FROM AUTHOR]

We estimate the demand for tourism on Oʻahu, Hawaiʻi, from multiple perspectives. While the literature on nonmarket valuation focuses on estimating the willingness to pay for single use value or a single purpose, this study applies onsite survey data to address visitors’ willingness to pay for multilayered tourism: for an Oʻahu trip as a whole and for individual beach visits on the island. Our survey data reveal that those visitors who have visited Oʻahu in the past do not necessarily visit beaches less frequently on subsequent Oʻahu trips. The estimated consumer surplus per person for a trip to Oʻahu is considerably large ($3,400–$5,480 based on the preferred estimate) and is in line with the literature on resort island travel costs. The aggregate surplus of all Oʻahu visitors would be approximately $21 to $34 billion. The surplus increases with the number of beach trips during each island visit, indicating that maintaining beaches enhances the demand for tourism as a whole. Our beach travel cost analysis also illustrates that the extent of substitution among different beaches is limited for Oʻahu visitors such that losing an Oʻahu beach is unlikely to be compensated for by access to the remaining beaches on the island.

This study examines the flood disaster management network within the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) from 2015 to 2021, identifying government department involvement and influence shifts. Key findings indicate a decrease in the centrality of the Public Security Office and Department of Transportation, suggesting a strategic shift toward more specialized, technology-driven disaster management. Conversely, the Science Bureau's increased engagement, from 8.43% to 12.84%, highlights a policy shift toward scientific research and technological innovation in managing flood risks. The analysis reveals underutilized communication between the Central Committee, the Poverty Alleviation Office, and the Publicity Department, highlighting opportunities for improved integration in disaster management and public communication strategies. To address these issues, the study suggests strengthening inter-departmental collaboration to leverage technological advancements in disaster management. It also recommends integrating flood disaster management with poverty alleviation initiatives to support affected populations comprehensively. Increasing the involvement of the Publicity Department is crucial for improving timely and transparent communication of flood-related data to the public. The conclusions advocate for an adaptive, strategically planned network approach to flood disaster management in the GBA, aiming to bolster responsiveness and preparedness for future flood events. HIGHLIGHTS The study reveals a strategic shift in the flood disaster management network within the GBA, with decreased centrality of traditional departments like the Public Security Office and Department of Transportation, and increased engagement of the Science Bureau, highlighting a move toward specialized, technology-driven approaches.; The study identifies underutilized communication between key departments, such as the Central Committee, the Poverty Alleviation Office, and the Publicity Department, suggesting significant opportunities for improved integration and coordination in disaster management strategies.; The study recommends enhancing inter-departmental collaboration, integrating flood management with poverty alleviation, and increasing the Publicity Department's role for better communication, advocating for an adaptive, strategic network approach to improve disaster preparedness and responsiveness in the GBA.;

BACKROUND AND OBJECTIVES: Mangrove silvofishery, a unique system that combine aquaculture with mangrove forests, presents a promising sustainable solution for Indonesia's coastal communities. However, in order to achieve broad implementation, it is essential to bridge the existing knowledge gap concerning the economic and environmental benefits associated with it. The aim of this study was to assess the four primary services rendered by the Blanakan mangrove silvofishery area in Subang District, West Java: carbon sequestration, fisheries productivity, nature-based tourism, and bird sanctuary.METHODS: Carbon storage was calculated by conducting vegetation surveys and utilizing allometric equations, which took into account both aboveground and belowground biomass. During the vegetation survey, data regarding the types of mangrove plants and the diameter of each tree at breast height was gathered. To quantify fisheries production, interviews were conducted with area managers and pond farmers who are engaged in silvofishery practices within the region. The point-count method was used to inventory the diversity of bird species. The analysis of natural tourism services encompassed an examination of visitor statistics, the state of the mangroves as a popular tourist destination, and the range of tourist activities available.FINDINGS: The study revealed the high capacity of the mangrove stands at the study location for carbon storage, with an estimated 137.9 tonnes carbon per hectare aboveground and 79 tonnes carbon per hectare belowground. Local communities actively engage in silvofishery practices within the Blanakan mangroves, cultivating fish and shrimp, with an average annual income of around 1,513 United States dollar per hectare. 2. The natural beauty of the Blanakan mangrove area attracts tourists with its diverse ecosystem and opportunities to see crocodile breeding facilities. Visitor numbers vary, averaging around 128 people per month until mid-2023. The Blanakan mangroves are home to a total of 23 bird species, contributing to a species diversity index of 2.1. Two species with significant conservation value were found: the critically endangered Javan Blue-banded Kingfisher (Alcedo euryzona) and the vulnerable Black-capped Kingfisher (Halcyon pileata).CONCLUSION: The results emphasize the importance of advancing and advocating for silvofishery as a primary alternative in Indonesia's mangrove conservation and rehabilitation initiatives, enhancing coastal environmental management. Community engagement is of utmost importance in the successful development of mangrove silvofishery, as it aims to tackle the issue of limited awareness and participation among the local community.

Climate change is predicted to have severe impacts on coastal communities, including sea level rise, flooding, and coastal erosion, and is expected to reshape many coastlines. One further, and often overlooked, consequence of the climate crisis is the threat posed to cultural heritage sites in the coastal zone. The threat to coastal cultural heritage (CCH) will inevitably impact both tangible (physical and material) and intangible (socio-cultural) components of cultural, historical, and archaeological character along frontline coastal communities. This poses substantial sustainability challenges for stakeholders and decision-makers for the management of cultural heritage assets and for management practices to respond to increasing threats from climate change. This paper uses five illustrative examples based on maximum variation principles to evaluate different strategies (or 'steering' processes) for managing coastal heritage resources in the context of climate change. These include the traditional 'preservationist' perspective and trajectories based on discontinuity or transformation. We examine these issues with reference to five post-European heritage assets located along the East Coast of the USA. While a consideration of steering processes is important, we argue that it is necessary to also embrace the policies and strategies for adapting to and mitigating the impacts of climate change through which processes of managing CCH unfold. Adopting such a perspective can lead to more nuanced approaches for understanding how CCH can respond to the challenges of a changing climate. [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]

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]

The concrete damages of climate change are intensifying, and adaptation efforts of actors around the world are increasing, especially in coastal regions. Recommending adaptation measures for specific regions and sectors and determining long-term strategies for mitigating global climate change is essential for reducing vulnerability to climate change. This research aims to estimate the changes in climatic parameters and thermal comfort zones to determine concrete targets and offer suggestions for sectors affected by possible changes. The changes that will occur until 2100 in the Antalya basin, which is located in the southernmost part of Türkiye and is a significant hub for agricultural production and tourism, were monitored spatially using Discomfort Index (DI) and Effective Temperature taking wind velocity (ETv). The Shared Socioeconomic Pathways (SSP): SSP 245 and SSP 585 predict that the quite cool areas prevailing in the area, according to ETv, will shrink by 24% and 46%, respectively, and the prevailing cold areas, according to DI, will shrink by 45% and 56%, respectively. By 2100, 5% of the area, according to SSP 245, and 25%, according to SSP 585, will turn into hot areas and move away from the comfort level. The fact that critical regions are areas with high vitality in terms of coastal tourism shows the need to prioritize adaptation policies. These discoveries are discussed in the context of critical issues such as water scarcity and food security, contributing to policy-making for effective management by suggesting specific adaptation measures. [ABSTRACT FROM AUTHOR]

Bangladesh is considered one of the hotspots of numerous devastating natural hazards around the globe due to its geographical location as well as its dynamic characteristics of coastal landforms. The coast of Bangladesh is a suitable test-bed for evaluating coastal vulnerability under complex land use systems and climatic conditions. Considering both the social and physical parameters is crucial to understanding the vulnerability of a coastal region. Therefore, this study has attempted to assess an integrated coastal vulnerability index for the most dynamic and non-uniform south-central and south-western coastal districts of Bangladesh. Initially, the study utilized ten physical parameters, including elevation, slope, storm surge height, sea level rise rate, rainfall, wind speed, mean tide level, cyclone track intensity, soil salinity, and soil permeability, to calculate the physical vulnerability index. Additionally, four social variables such as population density, literacy rate, household structure, and land use land cover are considered to assess the social vulnerability index. The final step involved combining these results to formulate an integrated coastal vulnerability index using the square root of the product mean equation. The study revealed that a large portion of Patuakhali (52.7%) followed by Bhola (28.7%), Barguna (27.7%), Shariatpur (13.6%), Pirojpur (9.3%), and Jhalakati (3%) districts are very highly vulnerable while western regions like Satkhira, Khulna, Bagerhat, Jashore as well as Narail has been identified as very low to low vulnerable. We suggest that this approach can efficiently assess coastal vulnerability and contribute to the development of a comprehensive strategy for coastal conservation, management, and policymaking. [ABSTRACT FROM AUTHOR]

Climate change and land use are major drivers of environmental and socioeconomic transformations in landscapes and in coastal areas. The objective of this study was to present an interdisciplinary and participatory research methodology for analysing the evolutionary process of a coastal case study, the Trabocchi Coast in the Abruzzo Region (Italy), from multiple perspectives, including climate change, technological history, conservation protocols, and social function. The goal was to assess the resilience of these coastal structures, i.e., their ability to cope and adapt to changes while maintaining their identity and recognition. The adopted approach combined qualitative and quantitative data from the meteorological analyses, literature review, and field investigations involving a participatory workshop, from which a significant portion of the analysed results presented here emerged. The results indicate that the Trabocchi Coast has undergone significant changes in recent decades, posing a serious threat to cultural heritage due to climate change (sea-level rise, coastal erosion, storms, flooding and salinisation), changes in use and mass tourism. However, these changes have also presented challenges and opportunities for coastal development, stimulating diverse resilient responses from local communities, ranging from resistance to innovation. The paper discusses the factors that may make the Trabocchi Coast a model of resilience considering these changes. This is supported by the role of local institutions as guarantors of the cultural heritage value of the trabocchi in that specific landscape context, as evidenced by the approval of the "Costa dei Trabocchi Special Territorial Project" by the Abruzzo Region in 2023. [ABSTRACT FROM AUTHOR]

Coastal lagoons are valuable ecosystems, providing socioeconomic benefits and supporting human populations and biodiversity. However, these systems face several challenges, making them vulnerable to both natural and human factors. In this study, we apply the Driver-Pressure-State-Impact-Response (DPSIR) Approach to conduct a comprehensive socioeconomic and environmental assessment of the Khenifiss Lagoon to promote sustainable development and support decision-makers. Located on the southern Atlantic coast of Morocco, the lagoon was designated a natural reserve in 1962, a biological reserve in 1983, and a protected wetland under the Ramsar Convention since 1980. This study represents the initial endeavor to conduct a comprehensive global and multidisciplinary environmental assessment of the lagoon by using a wide range of data sources, including relevant publications and reports, satellite images and remote sensing data, field observations, and interviews, all analyzed under the DPSIR framework. Our findings show that both natural and human factors have an impact on the ecosystem. Natural Factors associated with the geomorphological features of the region likely contribute to the silting of the lagoon, possibly intensified by a large shipwreck stuck at its inlet. Meanwhile, human factors encompass population growth (at a rate of 2% per year), tourism, shellfish farming, fishing, shellfish harvesting, and salt extraction. Our results reveal significant changes in the lagoon's condition in recent years, including a reduction in water body extent, a probable decrease in depth, and an increase in the accumulation of solid waste, plastics, and wastewater in three sectors spanning a total surface area of 464 ha (equivalent to 7% of the lagoon), a substantial expansion of the salt mining area encompassing 368 ha, and a remarkable loss of biodiversity, manifested in declining fish stocks and seabird populations. This study showed that the lagoon is positioned as a potential site for economic growth and serves to alert stakeholders and the local population to the ecosystem's environmental issues. Based on the findings of this study, we highly recommend regulating human activities within the lagoon, the removal of the wreck at the entrance, proper waste management, community awareness programs, and strict monitoring and enforcement of regulations to protect the environment. [ABSTRACT FROM AUTHOR]

Oñate, V.; Orejarena-Rondón, A.F., and Restrepo, J.C., 2024. A simple approach to the risk assessment of strategic infrastructure on the Colombian Caribbean coast. Journal of Coastal Research, 40(4), 749–767. Charlotte (North Carolina), ISSN 0749-0208. Strategic infrastructure at risk was identified on the Colombian Caribbean coast. The risk approach consisted of an estimation of the main coastal hazards (coastal erosion, mean sea-level rise, and changes in wave energy flux) and the exposure level, as one of the most significant components of vulnerability, through multicriteria analysis and GISs. It identified 88 strategic coastal infrastructures that are at risk, located less than 250 m from the coastline, and belong to the energy, health, education, and transportation sectors. Of these, 34.1% are at a medium-high risk level, and 20.5% are classified as high-risk critical infrastructure. The analysis also revealed that anthropogenic interventions, such as sand mining, poorly designed hard coastal protection structures (groins, seawalls, and breakwaters), or damage to marine ecosystems, might have a relevant weight on the risk degree of critical infrastructure, highlighting the relevance of appropriate coastal protection measures for strategic infrastructure. This simplified approach aimed to contribute to the risk management of such essential elements and guarantee compliance with the predisaster stage of disaster risk management. [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]

Wetlands across North America are invaded by an introduced lineage of the common reed Phragmites australis, and sea level rise has exacerbated the spread of this species. P. australis at tidal marsh-forest ecotones has rapidly been expanding into deteriorating forest, colonizing understory environments ahead of native marsh species. Early detection of P. australis at the ecotone will be critical to the management of this invasive species in coming decades. In this study, we develop and validate a new method for early detection of P. australis, using open access airborne LiDAR data that can uniquely penetrate the tree canopy and detect P. australis within the forest understory. The method was designed for areas of sparse to moderate tree cover, such as the forest edge where trees are dying and P. australis is expanding, where understory species mapping was previously impossible with most spectral data. To differentiate P. australis from shrubs and other understory herbaceous plants, we tested the effectiveness of several LiDAR-derived spatial metrics, including Mean distance, Point density, Scatter, Omnivariance, and Eigentropy, as inputs to a Support Vector Machine (SVM) classifier, followed by a smoothing algorithm to avoid occasional obstacles or disturbances. We compare among metrics and single- vs. multiple- metric-based classifications. The resulting best early detection method of P. australis achieved a classification accuracy of 91.48% at the development site, and between 56.16% and 80.65% accuracy at other test sites. This algorithm provides a cost-effective and high accuracy method of detecting understory P. australis using public airborne LiDAR data. Larger-scale application of this method will provide coastal resource managers and policy-makers with distribution maps of P. australis through time in open environments and the forest understory. More generally, this approach provides a framework for mapping understory species and plant functional groups using LiDAR-derived metrics.

Beachmeter is a Python script to automate the measurements of beaches based on a new delimitation method using digital elevation models (DEMs) of a coastal zone. It is developed to analyze multi-kilometre shorelines, especially in coastal monitoring. It can be opened as an ArcGIS toolbox. Filling out the Beachmeter form, the user inputs the raster DEMs from two measurement campaigns and information on the locally specific features of the study site. The Beachmeter delimits the beach boundaries and saves them as shapefiles. It creates beach elevation models, compares them to provide a differential map, and measures the basic morphological parameters.

Since the 1970s oil boom, nations surrounding the Arabian Gulf have witnessed rapid coastal urbanization, which accelerated in the early 2000s with the emergence of large-scale coastal ‘mega-projects’ designed to accommodate growing populations, attract international investments, and promote tourism. This development surge has had profound environmental impacts, including significant habitat modification, land use and land cover (LULC) change, and increased environmental pressure. Remote sensing (RS) technologies have become indispensable tools for monitoring these changes, offering cost-effective and non-intrusive methods to map and assess coastal zones. However, RS applications across the Arabian Gulf have been spatially limited, often focusing narrowly on specific cities or habitats while neglecting the broader geographical and coastal dimensions of urbanization. This study addresses this gap by conducting a systematic review of peer-reviewed RS literature from 1971 to 2022, covering the coastal regions of the eight nations bordering the Arabian Gulf. A total of 186 publications were categorized into three focal areas: 1) coastal urbanization and LULC, 2) coastal and marine habitats, and 3) environmental pressures and state changes. The results reveal a significant increase in RS studies in recent years, with around two-thirds of the publications (64.3%) appearing between 2016 and 2022. Studies predominantly focused on environmental pressures and state changes (35%), followed by habitat modification (27%), and coastal urbanization (20%). Geographically, RS research primarily concentrated on the coasts of the southern Gulf (UAE and Qatar) and western Gulf (Bahrain and Saudi Arabia), where major urban centers are located, while the northern Gulf (Kuwait and Iraq) and Iranian coast have been less studied. The systematic review highlights the need for integrated RS and GIS-based monitoring systems that combine different sources of RS data and in situ measurements to evaluate the Gulf as a unified system. Expanding spatial coverage, enhancing temporal analysis, and fostering regional collaboration are necessary to improve the understanding and management of coastal urbanization and environmental changes in the Arabian Gulf. This approach will more effectively inform decision-makers, and support more sustainable coastal management and long-term environmental resilience in the region.

Bluff landforms, sought-after for housing and development, present a hazard management challenge due to erosional processes despite the perceived safety of elevated land. This study focuses on the Neuse River Estuary in North Carolina, exploring coastal risk perception and erosion. A survey protocol was developed, and questionnaires targeted 246 residents with property within 100 m of the shoreline and 54 land use professionals in Craven County. To explore the connection of individual experiences with erosion, we use openly accessible LiDAR to quantify bluff retreat and erosion between 2014 and 2020, a period that encompasses Hurricane Florence in 2018. Our findings show: 1) survey results reveal a consensus among residents, with 90% observing alterations attributed to storm impacts, 2) preferences for addressing erosion lean towards structural measures, aligning with existing protection strategies (e.g., bulkheads, rip-rap) as opposed to nature-based solutions, 3) bluff tops are eroding at a higher median rate of -0.59 m per year, compared to -0.19 m per year for high sediment banks, and 4) an overall net volume decrease of approximately -1.89 cubic meters per year for Craven County, slightly more than the overall net loss for the Neuse River Estuary, which was -1.74 cubic meters per year. The findings underscore the need for a cohesive bluff erosion management plan, emphasizing the complexity of challenges and the importance of a holistic approach that combines technical studies with effective risk communication. [ABSTRACT FROM AUTHOR]

Efforts to control the spread of invasive alien species (IAS) in coastal dunes are essential to protect biodiversity and maintain the integrity of the ecosystem. However, the timing and extent of these control measures often do not consider their potential impact on dune morphodynamics. This study investigated how IAS control measures can affect sand dune mobility. Research involved monitoring short-term morphological and vegetation changes using close-range remote sensing along with historical wind data. Findings revealed that changes in vegetation cover significantly impacted dune system evolution, notably increasing sand mobility when IAS vegetation was removed. Considering the seasonal wind regime, dominated by offshore winds in the summer, removing vegetation during this period can promote seaward sediment transport, potentially resulting in sediment loss to the beach. These findings highlight the importance of understanding sediment mobility patterns when planning vegetation control actions within dune restoration strategies. [ABSTRACT FROM AUTHOR]

Throughout the Caribbean region, coastal areas are of vital importance for national incomes from the tourism industry. However, accelerated coastal development has impacted the coastal ecosystems, including the beaches, and deterioration of the shore results from cumulative impacts on both marine and coastal ecosystems. It is essential to identify the areas that need special attention for targeted management plans and actions, especially in areas with high anthropogenic pressure. This research proposes an integrated assessment of the conservation state of shore and coastal ecosystems in the Puerto Morelos National Reef Park (PNAPM) in the Mexican Caribbean, through the spatial monitoring of key parameters. A Geographic Information System (GIS) was employed to analyze the land use on the shore, foredune condition, morphological characteristics of the beaches, shoreline evolution, and the condition of coral reefs and seagrass meadows. The analysis identified the most critical areas in relation to shore deterioration and priority areas for the preservation of ecosystems. The spatial data obtained for the PNAPM can serve as a basis for ongoing shore monitoring, and targeted management actions through the designation of areas that require either preservation or ecosystem restoration practices. This methodology can be applied to other reef systems in the Caribbean. [ABSTRACT FROM AUTHOR]

This study aims to investigate the application of the principles of Good Environmental Governance (GEG) in handling beach abrasion in Bengkalis Regency. The research method used is a qualitative phenomenological approach. This research involves collecting in-depth and descriptive data through interviews with relevant stakeholders, such as local governments, environmental institutions, local communities and related experts. A phenomenological approach allows researchers to understand individual views and experiences regarding handling coastal erosion, as well as look for thematic patterns that emerge from the various narratives provided. The collected data was then analyzed using an analysis tool, namely Nvivo 12 Plus. The study results show that implementing Good Environmental Governance (GEG) in handling beach abrasion in Bengkalis Regency has great significance and urgency. GEG principles, such as a strong rule of law, active participation of all stakeholders, access to information, transparency, accountability, decentralization, and justice, provide a comprehensive framework for maintaining coastal environmental sustainability. The principles (GEG) are implemented through cross-sector collaboration, effective coordination between related parties, and increasing stakeholder awareness of environmental interests. Apart from that, the application of risk management is also an integral part of enabling rational and effective decision-making in managing coastal erosion. Barriers such as ineffective coordination, limited resources, low awareness, and conflicts of interest are highlighted, providing insight into the challenges in implementing GEG. The contribution of this research lies in providing an adapted framework for sustainable and equitable coastal management in Bengkalis Regency. Although valuable, this study has limitations, including the regional data focus and interview subjectivity. Future research should broaden the scope and explore socio-economic impacts and the role of technology in mitigating coastal abrasion. [ABSTRACT FROM AUTHOR]

Salt marshes play a critical role in supporting water quality, erosion control, flood protection, and carbon sequestration. Threats from climate change and human activities have prompted global restoration initiatives. We analyzed restoration efforts worldwide from 1978 to 2022, using the Web of Science database and SciMAT mapping tool. After a PRISMA screening to identify methodologies, success rates, and key indicators, a total of 62 publications underwent detailed analysis, to increase knowledge on the best practices to employ in future restoration interventions and evaluation of their effectiveness. The research reveals a growing interest in ecosystem dynamics, biodiversity, anthropogenic impacts, and ecosystem services. Assisted interventions emerged as the predominant restoration method, employing 15 indicators across vegetation, sediment, fauna, and water, each one using different metrics for the intervention evaluation based on how good the outcome of the interventions described in the reviewed studies met the desired result. Our analysis suggests that combining natural interventions such as managed realignment with reconnection to tidal waters, along with long-term monitoring of vegetation, fauna, and water indicators such as sedimentation and erosion rates, plant cover and biomass, as well as fauna diversity and density, leads to the most successful outcomes. We provide valuable insights into best practices for future restoration interventions, offering guidance to future practitioners and policymakers based on a comprehensive review of the scientific literature, contributing to the resilience of these vital ecosystems, and ensuring effective restoration actions in the coming years. [ABSTRACT FROM AUTHOR]

The coastal environment is not managed in a way that considers the impact of cumulative threats, despite being subject to threats from all realms (marine, land, and atmosphere). Relationships between threats and species are often nonlinear; thus, current (linear) approaches to estimating the impact of threats may be misleading. We developed a data‐driven approach to assessing cumulative impacts on ecosystems and applied it to explore nonlinear relationships between threats and a temperate reef fish community. We used data on water quality, commercial fishing, climate change, and indicators of recreational fishing and urbanization to build a cumulative threat map of the northern region in New South Wales, Australia. We used statistical models of fish abundance to quantify associations among threats and biophysical covariates and predicted where cumulative impacts are likely to have the greatest impact on fish. We also assessed the performance of no‐take zones (NTZs), to protect fish from cumulative threats across 2 marine protected area networks (marine parks). Fishing had a greater impact on fish than water quality threats (i.e., percent increase above the mean for invertivores was 337% when fishing was removed and was 11% above the mean when water quality was removed inside NTZs), and fishing outside NTZs affected fish abundances inside NTZs. Quantifying the spatial influence of multiple threats enables managers to understand the multitude of management actions required to address threats. [ABSTRACT FROM AUTHOR]

Coastal areas have become an important part of Indonesia's evolving economy, with a variety of commercial activities taking place. The island of Java has both northern and southern coastal areas, each with its own distinctive characteristics and products. The studies about coastal development through its product value chain are still limited. This study aimed to determine the value chain of fishery products in Java to provide recommendations for enhancing coastal management. For the northern coast, milkfish and ariid catfish from Juwana Coast (Pati Regency, Central Java) were selected, while Whiteleg Shrimp from Mendit Coast and Trisik Coast of Kulon Progo Regency, Yogyakarta were chosen to represent the southern coast. The study involved 48 respondents, including small and medium-sized enterprises (SMEs), farmers, fishermen, wholesalers, middlemen, retailers, restaurants, and consumers. The analysis techniques used in this study included Porter's value chain, Hayami's added value, Return/Cost (R/C) Ratio, and marketing margin analysis. The results of the study revealed that the products followed various channels in the value chain, with longer chains leading to higher prices for the end consumers. The findings also indicated that processed and creatively packaged products tend to command higher prices and generate greater profits. Coastal management should not only focus on upstream activities but also consider downstream processes to increase the value of coastal products. Efforts to enhance coastal management should consider key actors and government interventions through developing the coastal local products. [ABSTRACT FROM AUTHOR]

With the increasing global reliance on maritime oil transportation, oil spills pose significant environmental hazards to coastal ecosystems. This study presents a comprehensive quantitative framework for assessing oil spill risks along the Jiaozhou Bay coastline in China. The research begins with an analysis of historical spill data to construct representative oil spill simulation scenarios. The advanced MEDSLIK-II oil spill prediction model is then employed to simulate oil spill trajectories under these scenarios, focusing on key parameters such as oil thickness and mass to evaluate the hazard levels associated with each scenario. Subsequently, the Environmental Sensitivity Index (ESI) is utilized to assess the vulnerability of coastal zones, while Geographic Information System (GIS) techniques are employed for a spatial analysis and visualization of the results. The case study, covering a 26.87 km stretch of the Jiaozhou Bay coastline, reveals 10 high-risk zones with a total length of 8561.2 m. These areas are predominantly characterized by saltwater marshes, brackish water marshes, and inundated low-lying areas, with ESI rankings of 9 and 10, accounting for 24% of the 339 analyzed segments. The modeling results indicate that in the simulated scenarios, oil spills originating from the Huangdao Oil Port and Qianwan Port pose the greatest risks, with potential impacts extending up to 12 km and 15 km along the coastline, respectively. The study highlights the importance of considering multiple factors, including oil spill trajectories, coastal geomorphology, and ecological sensitivity, in comprehensive risk assessments. The proposed framework demonstrates potential for adaptation and application to other coastal regions facing similar oil spill risks, contributing to the advancement of coastal management practices worldwide. [ABSTRACT FROM AUTHOR]

Many barrier islands and spits (collectively, "barriers") throughout the world are highly developed. As low‐lying, sandy coastal landforms, barrier systems are naturally reshaped by processes associated with storms and sea‐level rise (SLR). The resulting landscape changes threaten development, and in response, humans employ defensive measures that physically modify barrier geometry to reduce relatively short‐term risk. These measures include the construction of large dunes, emplacement of beach nourishment, and removal of washover. Simulations conducted using a new coupled modeling framework show that, over decades to centuries, measures to protect roadways and communities alter the physical characteristics of barrier systems in ways that ultimately limit their habitability. We find that the pathway toward uninhabitability (via roadway drowning or community narrowing) and future system states (drowning or rebound) depends largely on dune management—because building dunes blocks overwash delivery to the barrier interior—and on initial conditions (barrier elevation and width). In the model, barriers can become lower and narrower with SLR to the point of drowning. The timing and occurrence of barrier drowning depends on randomness in the timing and intensity of storms and dune recovery processes. We find that under a constant rate of SLR, negative feedbacks involving storms can allow barriers that do not drown to rebound toward steady‐state geometries within decades after management practices cease. Plain Language Summary: Barrier islands and spits (collectively referred to as "barriers") can naturally keep up with sea‐level rise primarily through a process called overwash. During overwash, sand from the beach is washed landward past the dunes by storm waves, leading to increases in barrier height (elevation) and width. Tall dunes, built to protect roadways and oceanfront properties, prevent overwash from elevating the existing barrier landscape. Here we use a new model to show that over many decades to centuries, an unintended consequence of rebuilding tall dunes in the aftermath of storms, which then block future overwash, is the narrowing and lowering of barriers relative to sea level. In some cases, this leads to complete drowning of the barrier interior. In other cases, once humans stop rebuilding dunes, the landscape recovers in as little as a few decades. Key Points: Counterintuitively, with higher dune design heights and lower/wider initial barrier geometries, barriers become uninhabitable soonerRandomness in dune‐storm interactions dictates whether or not a barrier drowns after management ceasesSimulations suggest barrier systems can recover in height, width, and cross‐shore position quickly (within decades) after management ceases [ABSTRACT FROM AUTHOR]

Developed barrier systems (barrier islands and spits) are lowering and narrowing with sea‐level rise (SLR) such that habitation will eventually become infeasible or prohibitively expensive for most communities in its current form. Before reaching this state, choices will be made to modify the natural and built environment to reduce relatively short‐term risk. These choices will likely vary substantially even along the same developed barrier system as these landscapes are rarely uniformly managed alongshore. Building on the results from a companion paper, here we use a new modeling framework to investigate the complexities in barrier system dynamics that emerge as a function of alongshore variability in management strategies, accelerations in SLR, and changes in storm intensity and frequency. Model results suggest that when connected through alongshore sediment transport, barriers with alongshore variable management strategies—here, the construction of dunes and wide beaches to protect either roadways or communities—evolve differently than they would in the absence of alongshore connections. Shoreline stabilization by communities in one location influences neighboring areas managed solely for roadways, inducing long‐term system‐wide lags in shoreline retreat. Conversely, when barrier segments managed for roadways are allowed to overwash, this induces shoreline curvature system‐wide, thus enhancing erosion on nearby stabilized segments. Feedbacks between dunes, storms, overwash flux, and alongshore sediment transport also affect outcomes of climate adaptation measures. In the case of partial, early abandonment of roadway management, we find that system‐wide transitions to less vulnerable landscape states are possible, even under accelerated SLR and increased storminess. Plain Language Summary: Because humans inhabit barrier islands and spits (collectively referred to as "barriers") these landscapes, that would otherwise naturally change shape in response to storms and sea‐level rise (SLR), are influenced by efforts to protect development with wide beaches and tall dunes. These features interfere with a process called overwash, which transports sand landward during storms, building barrier elevation relative to sea level. Here, we use a new model to better understand how these interactions influence the habitability of barriers over time. Our simulations show that different management decisions made for adjacent coastal segments affect each other in positive and negative ways. When communities nourish beaches, adjacent to segments managed for roadways, some nourished sand reaches the adjacent segments, reducing shoreline erosion there. Conversely, portions of barriers that are managed only for roadways allow some overwash to reach the barrier interior; this negatively affects neighboring communities by enhancing their shoreline erosion rates. We find that early abandonment of dune management along portions of barriers may prevent highly vulnerable future states, such as barrier drowning. As communities explore choices for climate adaptation, our findings reveal the importance of coordination among decision makers in adjacent communities to avoid undesirable outcomes. Key Points: When management strategies vary alongshore, their effects are coupled via alongshore sediment redistribution, influencing barrier evolutionBeach nourishment (along portions of barriers) induces system‐wide lags in shoreline retreat, even decades after nourishment practices ceaseMore overwash (due to lower dunes or increased storminess) can prolong habitability, but drives increased nourishment frequency elsewhere [ABSTRACT FROM AUTHOR]