Search Results (135)

Beach nourishment is a widely adopted nature-based solution for coastal erosion; however, its design efficacy and morphodynamic resilience under extreme wave conditions remain inadequately quantified, posing challenges for coastal hazard assessment. This study integrates physical-model experiments and XBeach numerical simulations to investigate the hydrodynamic and morphodynamic behavior of nourished beaches subjected to typhoon-driven extreme wave conditions at a headland-bay beach on Meizhou Island, China. Physical-model experiments were conducted to examine shoreline response and sediment redistribution under extreme waves for three nourishment tests. XBeach simulations resolved wave-induced currents, water-level variations, and sediment transport processes, enabling continuous tracking of nearshore hydrodynamics and beach profile evolution for three nourishment tests during Typhoon Doksuri. Results indicate that nourishment geometry and groin configuration play a dominant role in wave breaking patterns, sediment transport pathways and erosion–deposition distributions. Groin positions strongly influence alongshore sediment transport. Relocating the groin to an accretional zone reduces lee-side erosion and promotes a more stable shoreline. Steeper nourishment foreshore slopes promote offshore wave shoaling and breaking, enhancing fast wave-energy dissipation, shifting erosion seaward and limiting landward erosion extent. Consistent responses from both experimental and numerical results demonstrate that nourishment stability under extreme wave conditions is better characterized by the combined effects of erosion extent, erosion length, erosion depth, erosion volume, and alongshore and cross-shore sediment redistribution. The integrated physical–numerical approach provides a practical framework for assessing beach nourishment stability during coastal hazard events and offers guidance for the design and evaluation of resilient beach nourishment in wave-dominated, typhoon-prone coastal regions. Full article

Beach nourishment has become a globally adopted “soft” engineering measure to mitigate coastal erosion and sustain beach functions. This study conducts a systematic comparative analysis of beach nourishment practices between China and the United States, focusing on extensive project data and historical records. The research examines differences in historical development trajectories, spatial distribution patterns, restoration philosophies, funding mechanisms, and key technologies. The results reveal that the U.S., with over a century of experience, exhibits large-scale, high-frequency nourishment projects supported by diversified funding and long-term maintenance strategies. In contrast, China, despite a later start (circa 1992), has achieved rapid progress in both project scale and technical innovation, though its approach remains more government-led and structurally oriented. This study also identifies converging trends in resource concentration between the two countries, as measured by a proposed “beach nourishment primacy” index. Based on these findings, the work offers strategic recommendations for the coastal management of China, including the establishment of a national nourishment database, adoption of Regional Sediment Management, and greater integration of ecological engineering principles. This comparative analysis provides valuable insights for coastal nations seeking to optimize beach nourishment strategies in the face of growing climatic and anthropogenic pressures; to further advance these efforts, future research could explore the integration of interdisciplinary approaches and intelligent technologies, aiming to deepen our understanding of coastal system complexity and support the development of dynamic adaptive management. Full article

Beach nourishment is a widely used strategy to mitigate coastal erosion, yet its long-term geological impacts remain poorly understood. This study provides a multi-decadal synthesis of shoreline change and sedimentological evolution on the nourished beaches of Cape May and Wildwood, New Jersey, USA. Using shoreline positions from 1991 to 2024, we identify contrasting trajectories: Wildwood exhibits ‘persistent transition’ with severe northern erosion (EPR: −10.0 m/yr) feeding southwards accretion, while Cape May demonstrates a ‘managed equilibrium’ with widespread accretion (mean EPR: +1.15 m/yr). Wave energy correlations account for less than 15% of shoreline variability, indicating natural drivers have been superseded by human sediment inputs. Direct sediment comparison shows substantial textural transformation, with median grain sizes increasing from 153 to 435 μm to 467–982 μm and sorting degrading from very well to moderately well sorted, reflecting sustained disequilibrium. These findings are synthesized into a conceptual model where nourishment initiates feedback cycles that create human-dependent morphodynamic trajectories. This study concludes that the long-term resilience of developed coasts will depend on a strategic evolution from managing ‘sand as volume’ toward stewarding ‘sediment as a system,’ where textural compatibility is a primary determinant of success. Full article

Coastal erosion and increasingly severe storms present a growing challenge to the sustainable management of sandy shorelines. This study examines the geomorphological, sedimentological and geochemical responses of the Palanga coastal area in the Lithuanian Baltic Sea to beach nourishment projects implemented between 2006 and 2012. A multi-parameter approach was used, combining cross-shore profile monitoring with grain-size, magnetic susceptibility, mineralogical and geochemical analyses, in order to assess sediment redistribution and post-nourishment adjustments. The results demonstrate that nourishment projects substantially increased beach width, height and sand volume; however, the shoreline response was uneven in space and time. Subsequent years were characterised by gradual sediment redistribution along and across the coast, resulting in partial morphological stabilisation. Elevated concentrations of heavy minerals and trace elements immediately after nourishment indicated short-term enrichment from mineralogically distinct material, which was later diluted by natural reworking. The findings demonstrate that properly designed and monitored nourishment enhances coastal resilience, representing a human-induced adjustment within the prevailing coastal morphodynamic regime. While the socio-ecological effects were not directly evaluated, the identified geoindicators offer insights into the physical sustainability of coastal systems, emphasising the importance of evidence-based, adaptive management in line with the United Nations Sustainable Development Goals (SDGs 11, 13 and 14). Full article

Collecting accurate and reliable beach morphology data is essential for informed coastal management. The beach adjacent to the seawall on North Padre Island, Texas, USA has experienced increased erosion and disrupted natural processes. City ordinance mandates the placement of bollards to restrict vehicular traffic when the beach width from the seawall toe to mean high water (MHW) is less than 45.7 m. To aid the City of Corpus Christi’s understanding of seasonal beach changes, mobile lidar scanning (MLS) surveys with a mapping-grade system were conducted in February, June, September, and November 2023, and post-nourishment in March 2024. Concurrent uncrewed aircraft system (UAS) photogrammetry surveys were performed in February and November 2023, and March 2024 to aid beach monitoring analysis and for comparative assessment to the MLS data. MLS-derived digital elevation models (DEMs) were used to evaluate seasonal geomorphology, including beach slope, width, shoreline position, and volume change. Because MHW was submerged during all surveys, highest astronomical tide (HAT) was used for shoreline analyses. HAT-based results indicated that bollards should be placed from approximately 390 to 560 m from the northern end of the seawall, varying seasonally. The March 2024 post-nourishment survey showed 102,462 m³ of sand was placed on the beach, extending the shoreline by more than 40 m in some locations. UAS photogrammetry-derived DEMs were compared to the MLS-derived DEMs, revealing mean HAT position differences of 0.02 m in February 2023 and 0.98 m in November 2023. Elevation and volume assessments showed variability between the MLS and UAS-SfM DEMs, with neither indicating consistently higher or lower values. Full article

This study addresses the longevity of beach nourishment in a high-energy coastal environment. It focuses on a site along the Northern Portuguese Atlantic coast, characterized by intense littoral drift, in the order of 1 million m³ and N–S oriented. The region undergoes an erosion process, and some localities are protected by groynes and frontal defense structures. The longevity of beach nourishment is evaluated through a coastline evolution model (previously calibrated and validated), compared for three scenarios: the absence of nourishment, i.e., the “do nothing” scenario; a (one-shot) 4 million m³ of sand nourishment intervention; and a detached breakwater combined with nourishment. The recent morphological evolution of the study site is evaluated through the results of a four-year (2018–2021) topobathymetric monitoring program implemented by the Portuguese Environment Agency. The lifespan of the nourishment ranges from 4.5 to 7.5 years. While the detached breakwater significantly increases the beach width to the north, it also exacerbates sediment loss to the south, regardless of its position. However, after 10 years, the cumulative sediment balance for the combined scenario closely mirrors that of the nourishment-only approach. The discussion of these results includes reflections on the longer-term impacts of using coarser sediments (relative to native material) on coastline evolution and on the influence of the breakwater’s layout on nourishment longevity. Full article

This study investigates the causes and consequences of shoreline erosion at Kkotji Beach, a prominent tourist destination on the west coast of South Korea, where the degradation of the coastal environment has increasingly threatened the local tourism industry and economy, by employing a mixed-methods approach that combines field observations with MIKE 21 hydrodynamic simulations and by integrating perspectives from coastal engineering and the social sciences to develop practical, site-specific strategies for mitigating erosion, enhancing public awareness, and promoting sustainable coastal planning and development that support long-term environmental resilience and economic stability. The results show that dominant ebb currents drive southward sand transport, causing persistent northern erosion despite nourishment and highlighting the need for integrated management across engineering, policy, and community engagement. Full article

This work, conducted within the framework of the international network CRESTE (Coastal Resilience Using Satellites), examines the role of resilience in monitoring coastal evolution across diverse environments in Europe (France, The Netherlands), America (Mexico), Asia (China), and Oceania (Australia). High-resolution morphological datasets, derived from in situ measurements and video monitoring systems, were analyzed for wave- and tide-dominated beaches influenced by both climatic drivers and anthropogenic pressures. Findings indicate that beach resilience is strongly linked to system resistance, which depends on the intensity of climate drivers, including storm frequency, and site-specific conditions related to the type of sediment and its availability, and the presence of anthropogenic activities including coastal structures (e.g., Normandy, Yucatán) and shoreface nourishments (Netherlands). In Batemans Bay (Australia) and Hangzhou Bay (China), assessing the resilience is particularly challenging due to the combined influence of multiple drivers, fluvial inputs, and urban development. Accurate monitoring of coastal resilience across timescales requires accounting for long-term morphological, ecological, and socio-economic processes. This can be enhanced through satellite observations, which, when integrated with in situ measurements, numerical modeling, and artificial intelligence, support a more comprehensive assessment of resilience and refine projections under future climate change and sea-level rise; representing a key focus for further works. Full article

Coastal profile models are frequently used for the computation of storm-induced erosion at (nourished) beaches. Attention is focused on new developments and new validation exercises for the detailed process-based CROSMOR-model for the computation of storm-induced morphological changes in sand and gravel coasts. The following new model improvements are studied: (1) improved runup equations based on the available field data; (2) the inclusion of the uniformity coefficient (C_u = d₆₀/d₁₀) of the bed material affecting the settling velocity of the suspended sediment and thus the suspended sediment transport; (3) the inclusion of hard bottom layers, so that the effect of a submerged breakwater on the beach–dune morphology can be assessed; and (4) the determination of adequate model settings for the accretive and erosive conditions of coarse gravel–shingle types of coasts (sediment range of 2 to 40 mm). The improved model has been extensively validated for sand and gravel coasts using the available field data sets. Furthermore, a series of sensitivity computations have been made to study the numerical parameters (time step, grid size and bed-smoothing) and key physical parameters (sediment size, wave height, wave incidence angle, wave asymmetry and wave-induced undertow), conditions affecting the beach morphodynamic processes. Finally, the model has been used to study various alternative methods of reducing beach erosion. Full article

Coastal erosion is a growing concern in the Mediterranean region, where the combined effects of anthropogenic pressure, reduced fluvial sediment supply, and climate change-driven sea level rise and extreme storm events threaten the stability of sandy shorelines. This study examines the geomorphological impacts of the exceptional storm surge of 3 November 2023, associated with Storm Ciaran, which affected a vulnerable coastal segment north of the Morto Nuovo River in northern Tuscany (Italy). Using UAV-based photogrammetric surveys and high-resolution morphological analysis, we quantified shoreline retreat, dune toe regression, beach slope changes, and sediment volume loss. The storm induced an average shoreline retreat of over 5 m, with local peaks reaching 30 m, and a dune toe setback of up to 7 m. A net sediment budget deficit of approximately 1800 m³ was recorded, over 50% of the total volume added during soft nourishment interventions performed in the previous decade. Our findings highlight how a single high-energy event can match or exceed the annual average erosion rate, emphasizing the limitations of traditional shoreline-based monitoring and hard defense structures. This study highlights the importance of frequent, high-resolution monitoring focused on individual storm events, which is crucial to better understand their specific geomorphological impacts. Such detailed analyses help clarify whether long-term erosion trends are primarily driven by the cumulative effect of high-energy events. This knowledge is essential for identifying the most effective coastal protection strategies and for improving the design of defense structures. This approach is particularly relevant in the context of climate change, which is expected to increase the frequency and intensity of extreme events, making it imperative to base future planning on accurate, event-driven data. Full article

Posidonia oceanica seagrass, endemic to the Mediterranean Sea, provides ecological goods and ecosystem services of paramount importance. In shallow and sheltered bays, P. oceanica meadows can reach the sea surface, with leaf tips slightly emerging, forming fringing and barrier reefs. During the 20th century, P. oceanica declined conspicuously in the vicinity of large ports and urbanized areas, particularly in the north-western Mediterranean. The main causes of decline are land reclamation, anchoring, bottom trawling, turbidity and pollution. Artificial sand nourishment of beaches has also been called into question, with sand flowing into the sea, burying and destroying neighbouring meadows. A fringing reef of P. oceanica, located at Saint-Mandrier-sur-Mer, near the port of Toulon (Provence, France), is severely degraded. Analysis of aerial photos shows that, since the beginning of the 2000s, it has remained stable in some parts or continued to decline in others. This contrasts with the trend towards recovery, observed in France, thanks to e.g., the legally protected status of P. oceanica, and the reduction of pollution and coastal developments. The sand nourishment of the study beach, renewed every year, with the sand being washed or blown very quickly (within a few months) from the beach into the sea, burying the P. oceanica meadow, seems the most likely explanation. Other factors, such as pollution, trampling by beachgoers and overgrazing, may also play a role in the decline. Full article

Hydrotechnical structures reshape sandy coasts by altering hydrodynamics and sediment transport, yet their long-term effects on sediment texture remain underexplored, particularly in the Baltic Sea. This study investigates the spatial and temporal variations in sediment grain size near two ports (Šventoji and Klaipėda) on the sandy Baltic Sea coast, considering the influence of jetties, nourishment, and geological framework. A total of 246 surface sand samples were collected from beach and foredune zones between 1993 and 2018. These samples were analyzed in relation to shoreline changes, hydrodynamic data, and geological context. The results show that sediment texture is most affected within 1–2 km downdrift and up to 4–5 km updrift of port structures. Downdrift areas tend to contain coarser, poorly sorted sediments because of erosion and the exposure of deeper strata, while updrift zones accumulate finer, well-sorted sands via longshore transport. In the long term, the geological framework controls sediment characteristics. In the medium term, introduced material that differs in grain size from natural beach sediments may alter the texture of the sediment, either coarsening or refining it. The latter slowly returns to its natural texture. Short-term changes are driven by storm events. These findings highlight the importance of integrating structural interventions, nourishment practices, and geological understanding for sustainable coastal management. Full article

Coastal areas are increasingly vulnerable to erosion, a process that can lead to severe consequences such as flooding and land loss. This study investigates strategies for preventing and mitigating coastal erosion, with a particular focus on nature-based solutions, notably artificial sand nourishment. Artificial nourishment has proven to be an effective method for erosion control. However, its success depends on factors such as the placement location, sediment volume, and frequency of operations. To optimize these interventions, simulations were conducted using both a numerical model (CS-Model) and a physical flume model, based on the same cross-section beach/dune profile, to compare cross-shore nourishment performance across different scenarios. The numerical modeling approach is presented first, including a description of the reference prototype-scale scenario. This is followed by an overview of the physical modeling, detailing the experimental 2D cross-section flume setup and tested scenarios. These scenarios simulate nourishment interventions with variations in beach profile, aiming to assess the influence of water level, berm width, bar volume, and bar geometry. The results from both numerical and physical simulations are presented, focusing on the cross-shore morphological response of the beach profile under wave action, particularly the effects on profile shape, water level, bar volume, and the position and depth of the bar crest. The main conclusion highlights that a wider initial berm leads to greater wave energy dissipation, thereby contributing to the mitigation of dune erosion. Full article

Reliable coastal and offshore sediment transport data is a requirement for many engineering and environmental projects including port and harbour design, dredging and beach nourishment, sea shoreline protection, inland navigation, marine pollution monitoring, benthic habitat mapping, and offshore renewable energy (ORE). Novel sediment transport numerical modelling approaches allow engineers and scientists to investigate the physical interactions involved in these projects both in the near and far field. However, a lack of confidence in simulated sediment transport results is evident in many coastal and offshore studies, mainly due to limited access to validation datasets. This study addresses the need for cost-effective sediment validation datasets by investigating the applicability of four new suspended load validation techniques to a 2D model of the south-western Irish Sea. This involves integrating an estimated spatial time series of suspended solids concentration (${SSC}_{solids}$) derived from acoustic Doppler current profiler (ADCP) acoustic backscatter with several in situ water sample-based ${SSC}_{solids}$ datasets. Ultimately, a robust spatial time series of ADCP-based ${SSC}_{solids}$ was successfully calculated in this offshore, tidally dominated setting, where the correlation coefficient between estimated ${SSC}_{solids}$ and directly measured ${SSC}_{solids}$ is 0.87. Three out of the four assessed validation techniques are deemed advantageous in developing an accurate 2D suspended sediment transport model given the assumptions of the depth-integrated approach. These recommended techniques include (i) the validation of 2D modelled suspended sediment concentration (${SSC}_{sediment}$) using water sample-based ${SSC}_{solids}$, (ii) the validation of the flood–ebb characteristics of 2D modelled suspended load transport and ${SSC}_{sediment}$ using ADCP-based datasets, and (iii) the validation of the 2D modelled peak ${SSC}_{sediment}$ over a spring–neap cycle using the ADCP-based ${SSC}_{solids}$. Overall, the multi-disciplinary method of collecting in situ metocean and sediment dynamic data via acoustic instruments (ADCPs) is a cost-effective in situ data collection method for future ORE developments and other engineering and scientific projects. Full article

China has the world’s largest area of coastal aquaculture ponds, accounting for 39% of the total coastal aquaculture pond area worldwide. The rapid development of coastal aquaculture can significantly reduce global food shortages and support the development of marine economies on the Chinese mainland. However, coastal aquaculture ponds have been recognized as a beach hazard because they require pipes to be laid on the surface of the beach to discharge wastewater, polluting the beach and artificially dividing it into multiple segments. Based on a well-conceived remote sensing analysis, the erosion of beaches backed by densely distributed coastal aquaculture ponds was determined to be 10 m/y. A high-efficiency shoreline evolution model was verified using a satellite-derived shoreline dataset. For the present case, the Brier Skill Score (BSS) was calculated to be 0.55, indicating a moderate match between the modeled and satellite-derived shoreline datasets. The verified ShorelineS model was then used to predict the future evolution of a shoreline backed by densely distributed coastal aquacultural ponds. The retreat distance of the erosion hotspot was predicted to increase from 150 m in 2025 to 240 m in 2040. It is expected that the beach will lose the entirety of its dry part in the future. Potential strategies for beach protection include reasonable management and the ecological restoration and nourishment of the beach. Full article