Coastal Management Research Articles

UAV REMOTE SENSING APPLICATIONS IN BEACH-CLIFF SYSTEM MONITORING OF MORPHODYNAMIC PROCESSES

This study aims to evaluate the morphodynamic changes in a beach-cliff system in northeastern Brazil using high resolution data collected by UAV-SfM techniques to understand the geomorphic changes of the coastal landscape. The study used the Geomorphic Change Detection (GCD) method applied to short-term monitoring. This method uses Digital Elevation Models (DEMs) to determine the morphological changes in terms of both erosion and deposition through DEMs of Difference (DoDs). The difference gridded models are acquired by drone-based remote sensing, which can accurately and efficiently provide ultra-high resolution imagery and digital surface model data to measure volumetric changes. The geomorphic changes are observed on high resolution maps. The multi-temporal analysis revealed significant volumes of erosion and deposition throughout the beach-cliff system over the study period. In the first interval (May/2021 - November/2021), the cliff recorded -8,715 m³ of erosion and 2,816 m³ of deposition, with the beach sector showing erosion in 86% of its area. In the second period (November/2021 - March/2022), more severe erosion rates were observed on the cliff, reaching -10,853 m³ with 51% of its area eroded, while the beach showed the opposite behavior to that previously analyzed, with 73% of the beach experiencing an accumulation of sand and a positive balance of 5,960 m³. The results of this study can be fruitful in identifying the different of geomorphology hazards, coastal impacts of cliff urbanization and in the use of remotely piloted aircraft in coastal monitoring. Furthermore, the results indicate that the management of the beach-cliff system must be integrated and never dissociated, as is generally done by coastal managers. Keywords: Geomorphometry; DEMs; Drone-Based Remote Sensing; Mass Movement; Elevation and Volumetric.

Saltwater intrusion simulations in coastal karstic aquifers related to climate change scenarios

Coastal zones are crucial ecosystems supporting significant biodiversity and pertinent socio-economic activities. However, anthropogenic development contributes to socio-environmental complexities, particularly public water supply threats caused by climate change. This research presents a case study on the north-western coast of Yucatan, Mexico, which models potential saltwater intrusion in groundwater for multiple projections of sea level rise and recharge change due to climate change and its implications for the public water supply of the regional population and ecosystem. For this purpose, a previously calibrated and validated numerical model is employed, adapting its boundary conditions, keeping its calibrated hydrogeologic parameters, and considering the 2040 and 2100 climate change projections. Simulation results show that under these projections, significant saltwater intrusion may occur, reducing freshwater thickness due to increased salinity in groundwater and a loss of freshwater sources resulting from brackish-saline wedge intrusion. These scenarios are of particular concern as freshwater in this coastal region is the main source for public water supply and for freshwater input in coastal ecosystems. Moreover, this study underscores the susceptibility of karstic aquifers to salinization, especially in the face of rising sea levels, given their unique hydrogeological characteristics and substantial responsiveness to marine forcings. In spite of the uncertainties in global climate change predictions, this study enhances our understanding of the dynamics of these unique aquifers, and presents future saltwater intrusion projections that offer valuable technical insights to design and implement pertinent and resilient coastal aquifer management strategies.

Assessment of coastal flood risk scenarios on infrastructure in the Keta municipality in Ghana using a GIS approach

Coastal flooding and erosion, caused by climate change-induced sea level rise, pose significant threats to low-lying coastal areas worldwide. The African continent, including Ghana, has experienced severe impacts from these hazards, affecting the socio-economic development of coastal communities. This research focuses on the Keta municipality in Ghana. The Keta municipality is highly vulnerable to coastal flooding and erosion due to its low elevation and the construction of the Akosombo hydroelectric dam. This research aims to predict the impact of coastal flooding on infrastructure in the Keta municipality using different flood scenarios. It also fills the existing knowledge gap in understanding how future flood risk can impact on critical infrastructure and consequently on other vital socio-economic sectors in the coastal community of Keta. The study utilizes a Geographic Information System (GIS)-based approach, combining various datasets, including topographic data, administrative shapefiles, field survey points, and infrastructure data. Two flood scenarios were considered to assess areas at risk: a 2.5-m sea level flood scenario representing potential climate change events and a worst-case 5-m sea level flood scenario. The findings reveal that 3.3 km2 (9 %) of coastal land area, 3.9 km of roads, and 69 structures are at risk under a 2.5m sea level rise scenario, increasing to 7.1 km2 (19.4 %), 13.6 km of roads, and 667 structures under a 5m scenario. The study highlights the urgency of addressing these risks to protect coastal communities' socio-economic development and livelihoods. Recommendations include implementing appropriate coastal management strategies, improving infrastructure resilience, and promoting sustainable land-use practices. By understanding and addressing the future impact of coastal flooding, decision-makers can mitigate climate change's adverse effects on coastal areas and ensure the region's long-term sustainability.

A contemporary analysis of policy implementation for the coastal mangrove forest management in Bangladesh Sundarbans

Despite having more than 200 environmental laws and policies in Bangladesh, the overall ecological situation is almost beyond control. Relying on both primary and secondary sources of data, particularly the legal texts, this study delves into analysing the legal frameworks of Bangladesh pertaining to wildlife and biodiversity conservation in the Sundarbans mangrove forest (SMF). This study finds that the lack of implementation of stringent provisions is one of the key reasons for the failure to successfully conserve biological diversity in the SMF. The other reason that heavily accelerates environmental crimes in Bangladesh is the less severe punishment compared to other crimes. This study result reveals that the Animal Welfare Act 2019 imposes a mere BDT 10,000 (USD 116) for harming any animal. This study also finds that the Environment Court Act 2010 strives to expand environmental governance in every district, but the absolute authority of the Department of Environment (DoE) and its limited resources hinder such lavish expansion. Although the government has revised many outdated laws and policies and enacted new laws such as Bangladesh Environment Conservation Act 1995 (2023), Forest Act 2023, and Forest Conservation Act 2023, evidence indicates that most of the provisions were not successfully implemented due to overlaps with other laws and loopholes within the laws. In addition, complex bureaucratic systems significantly hamper the administration system in forest management. Furthermore, the Director General (DG) of the DoE’s sole authority often sparked concerns regarding the transparency and accountability of this department. Therefore, this paper examines the domestic legal system of Bangladesh for conserving biodiversity in the SMF.

Identification and assessment of the mudflat ecological vulnerability dominated by coastline evolution in Jiangsu

Coastlines have experienced profound alterations due to human disturbances and ocean dynamics against the backdrop of climate change and intensified anthropogenic activities. Significant modifications have occurred within the muddy coastal ecosystem, rendering it extremely susceptible to heightened levels of vulnerability. However, existing studies on coastal eco-environmental vulnerability have often overlooked crucial factors such as coastline erosion and siltation, particularly concerning coastline change. In this study, we assess coastline stability utilizing Landsat remote sensing imagery to investigate the vulnerability of coastal ecology alongside 24 economic and natural parameters, serving as indices for the Coastal Vulnerability Index (CVI) of the coastal eco-environment. Subsequently, we analyze the impact factors to vulnerability and predict trends in coastline change over the next 20 years to propose recommendations for sustainable development to safeguard the coastal eco-environment. Our findings reveal a trend towards coastline stabilization in Jiangsu, with significantly higher stability observed during 2010–2020 compared to 1985–2010. The overall CVI along the Jiangsu coast shows an downward trajectory over the past 15 years, primarily influenced by tidal action and coastal topography and geomorphology. Predictive modeling suggests Jiangsu coastline is bounded by the Sheyang estuary, with the coastline to the north dominated by stabilization and to the south dominated by siltation. Climate change, coupled with intensified human activities and future coastline alterations, may exacerbate vulnerability. Effective protection strategies for coastal ecosystems necessitate a comprehensive understanding of local natural conditions, resource availability, and socioeconomic dynamics. Governmental interventions should focus on reinforcing regulatory frameworks for coastal organism management, implementing coastal protection infrastructure, and enhancing supervision and management protocols for beachfront development, thereby fostering the sustainable management of muddy coastlines.

Tracing offshore marine ecosystem asset changes based on physical accounting: A case of Xiamen Sea Area

Assessing temporal and spatial changes in marine ecosystem assets is critical for the capitalized management of natural resources and their contribution to human well-being. However, quantifying these changes using different inclusion methods in the System National Account is a challenge. Ecosystem accounting has become a popular topic in recent years, particularly after the System of Environmental and Economic Accounting-Ecosystem Accounting was published in 2021. However, few practical studies have been conducted on offshore marine ecosystem accounting, including marine ecosystem assets and services. This study provides a systematic framework to prioritize the assessment of offshore marine ecosystem assets (extent and condition) in physical terms, including the determined indicators of physical accounts and the presentation of accounting results. We then used this framework to assess marine ecosystem assets in the Xiamen Sea Area selected from 2006 to 2020. The results show that: (a) The extent of the marine ecosystem in Xiamen decreased by 8.34% from 349.64 km2 to 320.49 km2, mainly caused by converting intertidal ecosystem into the land due to the demand for urban and industrial use sea. (b) The area of intertidal vegetation habitats (mangroves and salt marshes) increased from 23.22 hm2 to 132.2 hm2, with an increase of 4.7 times. The results also show that the restoration of the marine ecology in Xiamen has achieved remarkable results. (c) The marine ecosystem condition comprehensive index in Xiamen increased by 3.13% from 0.32 to 0.33. This shows that the marine ecosystem conditions in Xiamen remain well and have even slightly improved under the pressure of a rapidly developing economy and increasing population. This study provides practical technical methods for assessing offshore marine ecosystem in physical term to support integrated coastal management in coastal cities, and is important for assessing marine ecosystem services in the future.

Research on the implementation of integrated coastal management principles in Taiwan to mitigate disputes related to nuclear waste disposal

Taiwan's nuclear power plants are situated in coastal regions characterized by abundant socio-economic and ecological significance. In the context of managing high-level radioactive waste storage and disposal in the future, alongside technical considerations, there exist challenges related to public acceptance and communication. Radioactive waste management, including the siting of storage or disposal facilities, is a socially sensitive matter. The storage and disposal of radioactive waste represent a complex and multifaceted challenge that requires a comprehensive approach spanning multiple disciplines. One of the functions of Integrated Coastal Management (ICM) is to coordinate conflicts related to coastal use. The concept has been progressively embraced and implemented by nations globally. This study employs grounded theory to examine the perspectives of the interviewed stakeholders. It subsequently introduces the principles of integrated coastal management for conflict resolution post-compilation. The study utilizes the principles and mechanisms of integrated coastal management to address or alleviate the challenges related to radioactive waste management in our country. Issues concerning conflict in relation to storage and disposal.

The effects of changes in the coastline and water depth on tidal prism and water exchange of the Laizhou Bay, China

Laizhou Bay’s coastline has undergone multiple alterations due to human activities such as land reclamation and port construction. These changes in the coastline have led to modifications in the bay’s hydrodynamic conditions, which, in turn, can impact the marine environment and potentially result in a decline in biodiversity. To date, there has been no comprehensive study focusing on the coastline changes and hydrodynamic variations in Laizhou Bay. Therefore, this study utilizes coastline and water depth data from four time points—1990, 2003, 2013, and 2023—to establish a two-dimensional tidal current model of Laizhou Bay using Delft3D. Based on the good agreement between the simulated tidal current results and the observed data, this study further investigates the changes in tidal prism and water exchange in Laizhou Bay. The results indicate that tidal currents dominate the bay, with significant influences of topographic changes on the velocity and direction of tidal flows. The Eulerian residual current velocity is substantially lower than the tidal current velocity. Both tidal and residual currents play a role in controlling the distribution of materials within Laizhou Bay. Over the past three decades (1990-2023), the tidal prism in Laizhou Bay has shown a downward trend, with the tidal prism during spring, intermediate, and neap tides in 2023 reduced by 2.03%, 6.36%, and 10.19%, respectively, compared to 1990. The water exchange capacity has also weakened, with the half-exchange time being 71 days in 1990, increasing to 73 days in 2003 and 81 days in 2013, and showing a slight increase of 1 day in 2023 compared to 2013. Thus, changes in the coastline and water depth of Laizhou Bay can alter its hydrodynamic conditions, significantly impacting the tidal prism and water exchange, leading to a decrease in tidal prism and exchange rate, an increase in the water exchange period, a slower dispersion rate of pollutants, and a reduced water environmental carrying capacity. This research provides a scientific reference for protecting the marine environment and coastal management in Laizhou Bay.

Blue Accounting Literacy Perspective on the Tourism Sector in Indonesia

This research aims to analyze the challenges, role of government, and understanding of stakeholders in managing marine and coastal resources in Indonesia through the Blue Accounting approach. This research uses qualitative methodology with literature analysis of twenty-five relevant articles. The data was analyzed to identify the main challenges, government role, and stakeholder understanding in implementing Blue Accounting. Management of marine and coastal resources in Indonesia faces various challenges, including inadequate infrastructure and low public awareness. The government's role is critical in developing regulations, coordinating conservation efforts, and involving stakeholders. Stakeholder understanding of Blue Accounting and multi-stakeholder collaboration have proven effective in overcoming these challenges and improving resource welfare. This research provides insight into the importance of strong regulation, public education, and collaboration between governments, communities, and the private sector in the management of marine and coastal resources. The practical implications are the need to develop a blue accounting model that is more integrated with information and communication technology to improve the effectiveness of environmental monitoring and management. The study emphasizes the importance of data-based Blue Accounting approaches and multi-stakeholder collaboration in marine and coastal resource management, which has not been much applied in previous research.

Integrated Modeling Approach to Assess Freshwater Inflow Impact on Coastal Water Quality

The quality of freshwater input from tributaries of the Western Mississippi Sound (WMSS) impacts the quality of coastal water. Hydrological and hydrodynamic models can be coupled to assess the impact of freshwater inflow from coastal watersheds. This study aims to compare the performance of a hydrodynamic model and a hydrological–hydrodynamic coupled model in detecting the effect of freshwater inflow from the coastal watersheds of the state of Mississippi into the WMSS. A hydrological model, the Soil and Water Assessment Tool (SWAT), and a hydrodynamic model, the visual Environmental Fluid Dynamics Code (vEFDC), were coupled to evaluate the difference between the hydrodynamical modelling approach, which employs an area-weighted approach to define flow and nutrient concentrations, and the more recent coupling model approach, which uses a hydrological model to determine the flow and nutrient load of the model. Furthermore, a nutrient load sensitivity analysis of the effect of freshwater inflow on water quality in the WMSS was conducted in addition to assessing the repercussions of tropical depressions. Hydrological assessments of the major tributaries watersheds of Saint Louis Bay (SLB) at the WMSS were performed using the SWAT model. After calibration/validation of the SWAT model, the streamflow output from the SWAT was incorporated into the vEFDC model. Finally, hydrodynamic simulation of the SWAT-vEFDC model was conducted, and water quality output was compared at different SLB locations. The salinity, dissolved oxygen, total nitrogen (TN), and total phosphorus (TP) were assessed by comparing the vEFDC and SWAT-vEFDC outputs. The results indicated that hydrological input from the SWAT alters the flow and nutrient concentration results as compared to an area-weighted approach. In addition, a major impact on the concentration of TN and TP occurred at the location where the freshwater flows into SLB. This impact diminishes further away from the point of freshwater inflow. Moreover, a 25% nutrient load variation did not demonstrate a difference in water quality at the WMSS besides TN and TP in a post-tropical depression scenario. Therefore, the SWAT-vEFDC coupled approach provided insights into evaluation of the area-weighted method, and of hydrological model output to the hydrodynamical model, the effect of freshwater inflow into coastal waters, and nutrient sensitivity analysis, which are important for integrated coastal ecosystems management.

Bringing the Ocean to the Stage: Performing Coastal Values and Marine Management

Recent years have witnessed a seemingly constant call for improved understanding of human–ocean relationships, resulting in a “boom” of marine social science research, sometimes framed through the lens of ocean literacy. Defined as having an understanding of your influence on the ocean, and its influence on you, ocean literacy has gained traction in recent years as a way of better understanding the complexities of human–ocean relationships. However, despite this interest in the human dimensions of the ocean, coasts and seas, and a corresponding increase in broader marine social sciences research, qualitative and arts‐based research approaches continue to remain on the periphery of ocean research. This article explores the role of two ocean research “outliers,” intersecting arts‐based practice and marine social sciences through the lens of interconnected performances designed to explore the diverse values held by communities about their marine and coastal environment. Undertaken as part of the Diverse Marine Values project, the performances brought together ocean scientists, coastal and marine managers, and community members to create original performance pieces in Lerwick, Shetland, Scotland, and Portsmouth, England. Drawing heavily on applied theatre practice and scholarship, these distinct but interrelated performances utilised elements of forum theatre, devised theatre, and storytelling to address marine issues important to each respective community, with a view to understanding and fostering ocean literacy. In each location, the performance work illustrated ways in which theatre can serve as not only a tool for science communication, but also a research method to explore a range of ocean literacy dimensions. The performances helped the research team, comprised jointly of specialist theatre practitioners and experts in ocean literacy, coastal management, and plastics pollution to reshape data collection and stakeholder engagement. This collaborative theatre‐making process led to deeper conversations and embedded engagement within each coastal community. It also led to a fundamental reshaping of the questions and approaches that the marine managers and scientists asked of the communities in question. The article presents a discussion of the challenges of bridging these related, but often distant, disciplines, and highlights the role of arts‐based research practice in broader ocean literacy research and discourse.

Long-Term Trends in Significant Wave Heights in The Mediterranean as an Indicator of Climate Change

The Mediterranean coastal zones, particularly along the Nile Delta, are increasingly vulnerable to the impacts of climate change. This study examines the historical changes in the significant wave height along the Nile Delta coast over the past 84 years (1940-2023) at a depth of 20 meters. By synthesizing a comprehensive long-term wave data series using ERA5 reanalysis data and the MIKE21-SW model, the study establishes a robust foundation for analysis. To ensure accuracy, the observed wind data were contrasted against ERA5 data, and they were found to be similar to a great extent. Furthermore, the model's accuracy was rigorously validated against the observational data, ensuring the reliability of the results. Three methods were used to obtain the trends for the maximum wave height to ensure robust and reliable trend assessments (i.e., linear regression, Theil-Sen, and ElasticNet). The results were obtained and analyzed, revealing a statistically significant increase in the maximum wave heights during the study period. Particularly, seasonal analysis revealed a positive trend in maximum wave heights during winter and spring (0.15 to 0.67 cm/year respectively). Furthermore, the monthly analysis showed a positive trend in the wave heights for all months except July, August, and September. Specifically, there were notable increases from September to December, ranging from 0.24 to 0.92 cm/year. These findings are consistent with the global trends of increasing wave heights due to climate change. It is essential for developing adaptive coastal management strategies and designing resilient structures. Consequently, the results will assist coastal authorities in mitigating the impacts of climate change on coastal zones.

Monitoring Coastal Evolution and Geomorphological Processes Using Time-Series Remote Sensing and Geospatial Analysis: Application Between Cape Serrat and Kef Abbed, Northern Tunisia

The monitoring of coastal evolution (coastline and associated geomorphological features) caused by episodic and persistent processes associated with climatic and anthropic activities is required for coastal management decisions. The availability of open access, remotely sensed data with increasing spatial, temporal, and spectral resolutions, is promising in this context. The coastline of Northern Tunisia is currently showing geomorphic process, such as increasing erosion associated with lateral sedimentation. This study aims to investigate the potential of time-series optical data, namely Landsat (from 1985–2019) and Google Earth® satellite imagery (from 2007 to 2023), to analyze shoreline changes and morphosedimentary and geomorphological processes between Cape Serrat and Kef Abbed, Northern Tunisia. The Digital Shoreline Analysis System (DSAS) was used to quantify the multitemporal rates of shoreline using two metrics: the net shoreline movement (NSM) and the end-point rate (EPR). Erosion was observed around the tombolo and near river mouths, exacerbated by the presence of surrounding dams, where the NSM is up to −8.31 m/year. Despite a total NSM of −15 m, seasonal dynamics revealed a maximum erosion in winter (71% negative NSM) and accretion in spring (57% positive NSM). The effects of currents, winds, and dams on dune dynamics were studied using historical images of Google Earth®. In the period from 1994 to 2023, the area is marked by dune face retreat and removal in more than 40% of the site, showing the increasing erosion. At finer spatial resolution and according to the synergy of field observations and photointerpretation, four key geomorphic processes shaping the coastline were identified: wave/tide action, wind transport, pedogenesis, and deposition. Given the frequent changes in coastal areas, this method facilitates the maintenance and updating of coastline databases, which are essential for analyzing the impacts of the sea level rise in the southern Mediterranean region. Furthermore, the developed approach could be implemented with a range of forecast scenarios to simulate the impacts of a higher future sea-level enhanced climate change.

Outdoor recreation contributes to ecological changes along coastlines: Temperate United States cases highlight key impacts and ways forward

Coastal natural areas including sandy and rocky beaches comprise some of the United States’ most critical recreational and ecological resources. Through collaboration, governmental conservation agencies and non-profits forecast that over 2 billion coastline visits occur each year. Under contemporary conditions, coastal resource overuse endangers the integrity of both social and ecological systems. Existing and mounting concerns call for different coastal zone management strategies, including research into poorly understood and emerging disturbances. This work explains how recreational disturbances influence coastal environments through wildlife behavior changes, plant dynamics, and the quality of abiotic ecosystem elements. Atlantic and Pacific cases indicate that some outdoor recreation systems strongly affect habitat quality, sensitive species, and interacting communities. New insight into outdoor recreation’s contributions to ecosystem change will inform how coastal zone management agencies can implement stronger co-existence strategies for people and nature.

Strategic environmental assessment for sustainable coastal zone management in Saudi Arabia, aligning with vision 2030

AbstractThis research examines the role of Strategic Environmental Assessment (SEA) in promoting sustainable coastal zone management in Saudi Arabia, in alignment with Vision 2030. Focusing on key coastal regions, namely the Red Sea and Arabian Gulf, the study explores SEA’s capacity to guide development activities toward long-term environmental sustainability. Through a comparative analysis of SEA and traditional Environmental Impact Assessments (EIA), the study emphasizes SEA’s proactive, integrative, and participatory approach to decision-making. The findings illustrate how SEA enhances the strategic alignment of national environmental objectives by fostering resilient and sustainable strategies that balance development with conservation in Saudi Arabia’s coastal zones. Ultimately, SEA is identified as a crucial instrument in achieving Vision 2030’s sustainability goals, offering a pathway to safeguard coastal ecosystems while supporting economic growth.

Coastal communities' perceptions on coastal erosion and the protective role of seagrass meadows in Dar es Salaam, Tanzania

Seagrasses are recognized as a nature-based solution for mitigating coastal erosion. However, knowledge on coastal community perceptions regarding coastal erosion causes, impacts, potential mitigation, and the protective role of seagrass meadows is limited in Tanzania. Using stratified random sampling, 323 resident fishers from the Kinondoni and Kigamboni coastal municipalities of Dar es Salaam, Tanzania, were selected to participate in a questionnaire survey to understanding their perceptions of coastal erosion impacts and the protective role of seagrass meadows. Further insights were obtained through key informant interviews with village leaders, elders, and BMU leaders, as well as through nominal group technique involving various beach user groups, and non-participant observation. The study found that coastal communities are highly aware of the causes, impacts, and mitigation measures of coastal erosion, with a notable 85.1 % of survey respondents identifying increased wave energy as the main cause. Nominal group technique revealed various categories affected by erosion, including social activities, properties, sacred sites, livelihood stability, and future development opportunities. The key functions of seagrass meadows as perceived by respondents, including enhancing the natural beauty of coastal waters (97.8 %), supporting fisheries (94.4 %), and providing coastal protection (87.0 %), which ranked third. Destructive fishing was identified as the primary cause of seagrass degradation, notably more severe in Kinondoni. Based on the findings, this study recommends regular awareness campaigns on seagrass preservation. Policymakers should integrate seagrass preservation into broader coastal management plans, promote sustainable fishing, and engage communities to ensure the long-term protection of seagrass meadows as nature-based coastal protection solution.

Regional Mean Sea Level Variability Due to Tropical Cyclones: Insights from August Typhoons

This study investigates the interannual variations in regional mean sea levels (MSLs) of the northeast Asian marginal seas (NEAMS) during August, focusing on the role of typhoon activity from 1993 to 2019. The NEAMS are connected to the Pacific through the East China Sea (ECS) and narrow, shallow straits in the east, where inflow from the southern boundary (ECS), unless balanced by eastern outflow, leads to significant convergence or divergence, as well as subsequent changes in regional MSLs. Satellite altimetry and tide-gauge data reveal that typhoon-induced Ekman transport plays a key role in MSL variability, with increased inflow raising MSLs during active typhoon seasons. In contrast, weak typhoon activity reduces inflow, resulting in lower MSLs. This study’s findings have significant implications for coastal management, as the projected changes in tropical cyclone frequency and intensity due to climate change could exacerbate sea level rise and flooding risks. Coastal communities in the NEAMS region will need to prioritize enhanced flood defenses, early warning systems, and adaptive land use strategies to mitigate these risks. This is the first study to link typhoon frequency directly to NEAMS MSL variability, highlighting the critical role of wind-driven processes in regional sea level changes.

Exploring Deep Learning Methods for Short-Term Tide Gauge Water Level Predictions

Accurate and timely water level predictions are essential for effective shoreline and coastal ecosystem management. As sea levels rise, the frequency and severity of coastal inundation events are increasing, causing significant societal and economic impacts. Predicting these events with sufficient lead time is essential for decision-makers to mitigate economic losses and protect coastal communities. While machine learning methods have been developed to predict water levels at specific sites, there remains a need for more generalized models that perform well across diverse locations. This study presents a robust deep learning model for predicting water levels at multiple tide gauge locations along the Gulf of Mexico, including the open coast, embayments, and ship channels, all near major ports. The selected architecture, Seq2Seq, achieves significant improvements over the existing literature. It meets the National Oceanic and Atmospheric Administration’s (NOAA) operational criterion, with the percentage of predictions within 15 cm for lead times up to 108 h at the tide gauges of Port Isabel (92.2%) and Rockport (90.4%). These results represent a significant advancement over current models typically failing to meet NOAA’s standard beyond 48 h. This highlights the potential of deep learning models to improve water level predictions, offering crucial support for coastal management and flood mitigation.

Numerical evaluation of the impact of sandbars on cross-shore sediment transport and shoreline evolution

Nearshore nourishments are a common intervention used to mitigate sediment deficits in coastal areas experiencing erosion problems. This coastal intervention involves placing nourished sediments in the submerged zone of the beach profile to form an artificial submerged sandbar which are then distributed by natural forces occurring in the coastal zone. Coastal processes that control the morphological evolution of coastal zones operate on several spatial and temporal scales (seconds to years) and can be divided into cross-shore and longshore components. Usually, the numerical models that simulate the evolution of cross-shore profiles due to sediment transport within the profiles, are related with short to medium-term events (days to months), and shoreline evolution models, that allow for long-term analysis (years to decades), are typically only considering longshore sediment transport. Describing all the processes in a single numerical model is complex and computationally demanding, and therefore, the numerical models are typically focused on specific processes, categorized by their temporal and spatial scales. This article presents a numerical study focused on medium to long-term numerical modelling of coastal zone evolution, examining the combined effects of cross-shore and longshore sediment transport processes of sediment transport. The model incorporates two simplified numerical models: LTC - Long Term Configuration, for shoreline evolution and CS-Model, for cross-shore sediment exchanges. Applied to nine different sandbar scenarios, model results revealed that disturbances in sandbar volume tend to return to equilibrium through cross-shore sediment transport processes. In situations that considered a constant sandbar volume alongshore, the longshore effects are null, because the volume entering in the coastal domain is equal to the volume leaving, and the sediment balance is only dependent of the cross-shore processes. Variable sandbar volume alongshore leads to impacts on shoreline position due to longshore sediment transport gradients generated by the sandbar disturbance. The results demonstrate the potential of the proposed combined model for medium to long-term projections, allowing for the interpretation of how physical aspects of nearshore nourishments evolve. These aspects include sandbar volume, shoreline position, berm width, and shoreline displacements induced by cross-shore and longshore sediment transport processes. These parameters aid in understanding sandbar-beach sediment dynamics, which is valuable for supporting coastal management, particularly in the development and design of shoreface sand nourishments, enabling the optimization of sand resources.

Variation of suspended-sediment caused by tidal asymmetry and wave effects

Suspended sediment plays an important role in coastal topography evolution and ecological environment change. To obtain a clear picture of the underlying mechanisms, we studied the response of suspended sediment dynamics to tidal current and wave-current interactions using the wave-current-sediment model of SCHISM. The results revealed evident tidal asymmetry in the study area, and showed that the suspended sediment concentration (SSC) markedly changes within a tidal cycle. We also disassembled the wave–current interactions to determine the contribution of each physical mechanism of the wave and hydrodynamic models. Regarding the importance of various effects of wave-current interactions on SSC, the wave-induced bottom shear stress and wave-induced radiation stress should be considered. The importance of advection in horizontal space is comparable to that of wave-induced bottom shear stress and wave-induced radiation stress, and is greater than that of the other types of wave energy advection. This study successfully explained all the mechanisms that influence the variation of SSC to the southwest of Hainan Island, which is helpful for coastal management and could provide a reference for other coastal areas.