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Guru Prasath, J.; Sannasiraj, S.A., and Chandramohan, P., 2024. Nearshore morphological changes due to severe cyclonic storm activity along the east coast of India. Journal of Coastal Research, 40(4), 696–713. Charlotte (North Carolina), ISSN 0749-0208. Nearshore waves, wind, and tidal current mobilize seabed sediments; sort, transport, and redistribute the sediments; and modify the nearshore seabed morphology. Waves play a dominant role in morphological changes among winds, waves, and tidal currents. The nearshore wave breaking induces the initiation of sediment movement, and the associated alongshore current transports a large volume of sediments that tend to either accrete toward or erode from the beach face and seabed. Sediment transport rate in the nearshore waters during cyclones is higher than that under normal conditions. The measured changes due to Cyclone Nivar in November 2020 in the nearshore morphology along the Mahabalipuram coast are examined to understand the response of nearshore morphology to cyclonic wave-induced forcing. The beach-profile measurements across 10 transects at 100 m spacing covering about 1000 m along the coast were measured before and after the passage of Cyclone Nivar as a part of the present field study. The evolving beach profiles during Cyclone Nivar were simulated using the storm-induced beach change (SBEACH) model, which is a cross-shore profile evolution model. The changes due to berm erosion and deposition of nearshore sand bars have been compared from field measurements data and model prediction. The calibrated model was then used to simulate the beach profile response at two other locations along the cyclone-affected coastline to examine the shoreline impact. The calibrated model can be used along the coast to understand the poststorm profiles of the beach with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Whitley, A.E.; Figlus, J.; Valsamidis, A., and Reeve, D.E., 2021. One-line modeling of mega-nourishment evolution. Journal of Coastal Research, 37(6), 1224–1234. Coconut Creek (Florida), ISSN 0749-0208. As many coastal areas of the world suffer from chronic erosion, innovative solutions beyond traditional local nourishment must be explored. One such solution is the implementation of mega-nourishments (MNs), where a large sediment volume is deposited in a single location and redistributed via natural processes, thereby feeding adjacent beaches. Robust numerical modeling methods are needed to evaluate potential MN sites at coastal locations around the world. Two one-line numerical modeling approaches of MN evolution are presented using the Coastline Evolution Model (CEM) and GENESIS + Cascade (GenCade). Both models are parameterized for the Sand Motor (SM) that has been constructed on the Dutch coast to explore the feasibility of the MN approach. Here, a variety of K coefficients in the Coastal Engineering Research Center (CERC) sediment transport equation are tested since traditionally calibrated and used values may not apply for MN features. Both models are found capable of reproducing the shoreline morphological patterns observed at the SM over the first 3.5 years. GenCade shows a low difference between measured and modeled coastline position overall, showing accurate predictions of absolute shoreline position. CEM is able to capture feature tip migration due to its wave shadowing algorithm. The best results from both models can be obtained for higher K values than those commonly suggested in the literature. Given the size of a mega-nourishment relative to traditional nourishments, it is likely that a higher-than-usual K value may be a better fit when simulating mega-nourishments in a one-line model. [ABSTRACT FROM AUTHOR]

Tak, W.J.; Jun, K.W., Kin, S.D., and Lee, H.J., 2020. Using drone and LiDAR to assess coastal erosion and shoreline change due to the construction of coastal structures. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 674-678. Coconut Creek (Florida), ISSN 0749-0208. Recently, The construction of structures on the coastal zone near estuaries, which are the supply sources of sediments, causes a variation in the waterway; this induces a change in the surrounding coasts, and the resulting coastal erosion can adversely affect the lives of the local residents. In the case of a balanced sediment flow, the quantity of the sediment deposited on the coast is equal to the quantity of the released sediment. However, an increase in either of the quantities causes an imbalance in the sediment transport; consequently, the sand is either deposited or eroded in the coastal or proximate shore regions. In this study, the changes in the shoreline and Wolcheon Beach region located on the east coast of Korea was monitored between 2010 to 2019 investigate the phenomena of coastal erosion and beach deformation. The shorelines, beach width, and beach profile were primarily monitored by employing a drone and a terrestrial LiDAR. The results showed that the sediments were transported northward in summer and southward in winter until 2010 in Wolcheon Beach; however, this seasonal sediment transport was blocked during 2011–2012 by the construction of coastal structures such as breakwaters, leading to partial coastal erosion and sedimentation. Wolcheon Beach originally had the coastal characteristics of the Korean East Coast region (2010), but the sediment transport changed due to the variations in the waterway by the construction of coastal structures, leading to a significant change in the coast (2011). In addition, the northern beach volume increased with respect to estuary, while the southern beach volume decreased. When the offshore breakwater was constructed, the northward sediment occurred dominantly in the shield area. In particular, the planar layout of the harbor facilities concentrated the waves, which increased the quantity of the northward sediment. [ABSTRACT FROM AUTHOR]

Hwang, B.-H.; Do, K.-D., and Chang, S.-Y., 2023. Morphological response of Storm Hinnamnor at Songjeong Beach using UAV-derived data. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 126-130. Charlotte (North Carolina), ISSN 0749-0208. This study investigated the morphological response of a wave-dominated beach to large storms via field data collection. The field data were collected on Songjeong beach facing SE in the south-eastern corner of Korea. This study measured pre- and post-storm beach volumes by Storm Hinnamnor using Unmanned Aerial Vehicle (UAV). In this storm event, the peak of the significant wave was 10 m, and the wave period mainly varied between 10.9s under stormy conditions. The incident waves were mostly easterly at 90-115.5°. During this event, due to the strong storm intensity, the upper part of the sediment showed significant erosion along the entire beach, and net accumulation took place in the revetment area by overwash. The highest substantial loss occurred in the SW section of the study area, associated with the wave direction. Compared to the SW section, the mid and NE section of the study area eroded sediment. It was transported to the upper beach near the revetment area, suggesting that the onshore sediment transported was dominated in this area. After the storm, the local government undertook beach nourishment to restore the deposition sand on the revetment to the beach. This study carried out the UAV survey after beach nourishment and estimated the sediment volume by overwash. As a result, it was estimated that the amount of sand transported to the offshore area was 9533 m3, and the overwash deposition volume was 1441.3 m3. This study shows that UAV surveys can effectively estimate the morphological response of storm on the beach. [ABSTRACT FROM AUTHOR]

Thomas, J.; Velamala, S.N., and Prasad, K.V.S.R., 2019. Numerical simulation of tidal constituents in Thane Creek and the Ulhas estuary, west coast of India. Journal of Coastal Research, 35(2), 376–388. Coconut Creek (Florida), ISSN 0749-0208. Complex tidal progression in creeks and estuaries attract a large number of researchers around the globe. The main motive of the present work is to study the complex tidal variation of Thane Creek and the Ulhas estuary on the west coast of India. A Delft3D model was applied to simulate its depth-averaged hydrodynamics and tidal propagation along the system, and the calibration and validation of this model revealed its accuracy. The system was classified as hyposynchronous; a gradual decrease in the amplitude was noticed from mouth to upstream in all seasons. The interpretation of the major tidal constituents amplitude and phase, shallow water constituents, form number, and tidal asymmetry showed the dynamic nature of the system. The form number results revealed that the tide in Thane Creek and the Ulhas estuary is mixed semidiurnal. The tidal asymmetry parameter indicated a seasonal variation of ebb and flood current in Thane Creek and the Ulhas estuary, which favors sedimentation processes in the system with consequent erosion and deposition. For the future, these results will help in understanding sediment transport and the corresponding shoreline changes and the biogeochemical processes of this dynamic system and help to establish its sustainability. [ABSTRACT FROM AUTHOR]

Duy, D.V.; Tanaka, H.; Mitobe, Y.; Anh, N.Q.D., and Viet, N.T., 2018. Sand spit elongation and sediment balance at Cua Lo Inlet in Central Vietnam. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 32–39. Coconut Creek (Florida), ISSN 0749-0208. Erosion is significant on the downdrift beach of Cua Lo Inlet, which is located in Central Vietnam. The elongation of Cua Lo Inlet's updrift sand spit together with severe erosion of the downdrift bank is raising numerous social problems such as flood safety and land loss. In this study, a series of Landsat and Google Earth images were used to analyze and investigate the inlet recent morphological changes and evolution. Since 1970 the inlet has constantly migrated towards the sediment transport pathway, and its traveling distance has reached 1700 m. In order to quantitatively investigate such characteristics, the tip coordinates and the area of the sand spit updrift of the inlet were calculated. In particular, the area of the sand spit has increased remarkably, and the increasing rate is almost constant. Using this value, the rate of sand volume transported along the updrift sand spit by the waves was estimated and it is in good agreement with the longshore sediment transport rate of the surrounding beach. [ABSTRACT FROM AUTHOR]

ABSTRACT Zuckerman, S. and Anderson, S., 2018. Bathymetry and water-level estimation using X-band radar at a tidal inlet. Knowledge of bathymetry in coastal areas is a key factor for maintaining shipping channels, identifying hazards to navigation, and measuring sediment transport processes. Remote-sensing techniques are crucial for this purpose, because in situ methods are often costly, time-consuming, and less frequent in occurrence. This paper presents a derived bathymetry and water-level retrieval algorithm that operates on time-series X-band marine radar data. The algorithm is designed to operate on a long-term continuous data stream, generating updated water-level measurements and bathymetry maps as new data are collected. In step 1, individual data sets are first processed to retrieve dominant wave numbers over a pyramid of overlapping tiles. In step 2, depths are estimated at each pixel location in the domain using the shallow-water wave dispersion relation. Last, results from step 2 are used to estimate the current water level. Updated water levels are used to tide correct a series of individual depth estimates, which are averaged together to produce an updated bathymetry map. In this way, no a priori or external data sources from the survey area are required. A 2-month-long experiment was conducted at Beaufort, North Carolina, to test the algorithm and quantify the frequency at which adequate signal levels were present for valid retrievals. Derived bathymetry and water-level results are presented and compared against ground truth. Derived measurements agree well with ground truth, although bathymetry accuracy degrades in areas of the domain with large bottom gradients or strong tidal currents. [ABSTRACT FROM AUTHOR]

ABSTRACT Kim, M.; Lim, H.S.; Do, J.-D.; Kim, S.-S.; Lee, H.J., and Shim, J.-S., 2018. Variations of nearshore currents induced by seasonal waves in Haeundae. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1551–1555. Coconut Creek (Florida), ISSN 0749-0208. Haeundae, located on the southeastern coast of the Korean Peninsula, is a famous sand beach with a 1.6 km long, 70 m wide coastline. It suffers from wave-induced beach erosion in both summer and winter. For beach restoration, the Korean government has conducted beach nourishment (620,000 m3), and installed submerged breakwaters at both ends of the beach. Despite these efforts, the beach is still vulnerable to erosion caused by high waves. To understand beach erosion processes and sediment transport mechanisms, the government initiated an R&D project for the development of coastal erosion control technology since 2013. As part of the project, we have measured over three years of AWAC measurements at a water depth of 22 m and 1.8 km from the beach. Intensive measurements of wave, current, sediment transport near the surf-zone in summer and winter have been made using AWAC, VECTOR, and ADV with OBS. Analyses of nearshore currents induced by seasonal waves in the surf-zone have shown that cross-shore currents in summer are mainly induced by strong waves from the SSW or S that propagate to the beach due to wave breaking and shoaling effects on the reef near the beach. However, longshore currents in winter are induced by high waves from the E or ESE that propagate to the shoreline by diffraction at the east coastline. Eroded sand in summer returns along the beach by cross-shore and weak longshore currents induced by waves from the SSW or S. However, suspended sand in winter is moved to the west by strong longshore currents induced by waves from the E or ESE. Due to its pocket beach shape, beach erosion and sediment transport are caused by variations of nearshore currents induced by seasonal waves. [ABSTRACT FROM AUTHOR]

Marcomini, S.; López, R.; Picca, P.; Madanes, N., and Bertolín, L., 2017. Natural coastal dune-field landforms, plant communities, and human intervention along Buenos Aires northern aeolian barrier. The dune field that stretches NE of Buenos Aires coast has been altered by urbanization since the early 20th century, with a maximum urban growth reached in 1970 that generated important changes in natural dune landforms and vegetation cover. The introduction of some exotic shrub and tree species has increased dune-field stabilization and changed wind transport rates on it and toward the beach. This lack of aeolian sediment supply to the beach caused subsaturation in marine littoral drift currents, increasing beach erosion along several resorts located along the northern Buenos Aires coast. Additionally, some native herbaceous species, at some time dominant in the past in dune communities, have been replaced by these foreign woody plants, altering consequently the structure and composition of the original plant communities and, indirectly, dune growth, activity, and mobility. The purpose of this paper is to study the original geomorphology and some basic attributes of the natural plant communities that characterize the coastal dune field to establish the relationship between the original aeolian dynamics and man-induced changes in the evolution of the coastal system. This study documents dune morphology and salient aspects of the associated vegetation (floristic composition, abundance of each species) over an original dune field and discusses the impacts of afforestations accompanying dune-field real-state developments. In the future, coastal management should regulate the expansion of forested areas in the dune barriers and preserve natural dune fields as potential reserves of sand for beach equilibrium. [ABSTRACT FROM AUTHOR]

Restrepo, J.C.; Schrottke, K.; Traini, C.; Ortiz, J.C.; Orejarena, A.; Otero, L.; Higgins, A., and Marriaga, L., 2016. Sediment transport and geomorphological change in a high-discharge tropical delta (Magdalena River, Colombia): Insights from a period of intense change and human intervention (1990-2010). There is strong indication that environmental changes and human interventions have affected freshwater discharge and sediment flux in the Magdalena River (northwestern South America) within the period from 1990 to 2010. Thus, stream flow, suspended sediment load (SSL), and riverbed dynamics were analysed in this study for estimating changes in the suspended sediment transport regime as well as of erosional/depositional patterns in different zones of the delta. It can be shown that stream flow increased at a higher rate than suspended sediment transport, promoting changes in the sediment transport regime. Erosion appeared at the mouth/frontal bar and the outlet zones and modified the sedimentary balance within the prodelta in the early 2000s. There is indication that cycles of erosion and accretion were controlled by the magnitude of fluvial discharge and riverbed scouring in the river outlet, whereas effluent diffusion and sediment dispersion were dominant in the delta front. High freshwater discharge, as buoyancy inputs, promoted the transfer of sediments from the river channel to the outer prodelta through the upper layers of the water column. Total sediment accumulation in the delta corresponded to <5% of the annual mean SSL of the Magdalena River. Overall, delta morphology remained relatively stable, experiencing a slow progradational state with highest sedimentation rates (≤1430 mm y−1) in the deepest zones. [ABSTRACT FROM AUTHOR]

Al-Nasrawi, A.K.M.; Jones, B.G., and Hamylton, S. M., 2016. GIS-based modelling of vulnerability of coastal wetland ecosystems to environmental changes: Comerong Island, southeastern Australia. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 33-37. Coconut Creek (Florida), ISSN 0749-0208. Sustainable management of coastal zones has become a complicated issue. The majority of the human population lives along the coast, where their activities, together with a range of environmental changes, have altered the natural ecosystem processes and caused changes in coastal wetlands. To ensure sustainable use of coastal resources, a comprehensive set of modelling tools can help managers to make decisions. This study uses Comerong Island (southeastern NSW, Australia) as a case study to demonstrate the importance of modelling modifications to environmental change. Several data-based modelling approaches are employed to explore how human activities have altered this estuarine island setting over the last sixty years (1949 - 2014). Multi-temporal changes in land cover, shorelines and sediment delivery are estimated from remote sensing data, GIS analysis, and laboratory tests on water and sediment samples (grain size, X-ray diffraction and loss on ignition and water analysis). Results show there are significant changes to the areal extents and elevation of mangroves, saltmarshes and shorelines in the wetlands on Comerong Island over the time period of analysis, including northern accretion (0.4 km2), eastern, middle and southern erosion (0.7 km2) of the island. The implementation of modelling using GIS tools, water and sediment samples to monitor ecosystem processes, such as sediment transport and erosion/deposition, will allow resource managers to make more informed decisions by evaluating the potential consequences of the existing situation. [ABSTRACT FROM AUTHOR]

Cáceres, R.A.; Zyserman, J.A., and Perillo, G.M.E. 2016. Analysis of sedimentation problems at the entrance to Mar del Plata Harbor. Mar del Plata Harbor is an important center for the fishery industry in Argentina, and it has become an attractive site for international tourism because of the recent construction of a cruiser ship terminal. However, further development of this port halted several years ago because of the recurrent sedimentation problems in the access channel and basins. This site is characterized by advancement of the shoreline south of the harbor and a sandbank that develops across the access channel, while downdrift erosion and the associated shoreline retreat are due to partial blockage of the sediment transport caused by the harbor breakwaters. The mechanisms responsible for these sedimentation and erosion processes are examined using a coastal area morphological modeling system, MIKE 21/3 Coupled Model Flexible Mesh, developed by DHI. The morphological model was calibrated and validated against measured bathymetric changes. The model was then applied to a medium-term simulation with particular interest in the assessment of the effectiveness of re-establishing the design depth of the access channel through dredging. This morphological modeling allowed enhanced understanding of the main hydrodynamic and sedimentological processes occurring around the harbor entrance, as well as obtainment of information potentially useful for maintenance dredging. It was determined for the present hydrosedimentological conditions that the sandbank moves toward the access channel with high sedimentation rate. This means the navigation channel requires regular maintenance dredging or the construction of additional sediment retention interventions such as sediment traps, extension of the breakwater(s), etc. The efficiency of any intervention from the point of view of reducing sediment deposition at the harbor access should be verified before its implementation. In all cases, the northward transport would still be blocked, so artificial sediment bypass should be considered to protect the beaches north of the harbor. El puerto de Mar del Plata es un importante centro para la industria pesquera en Argentina y se ha convertido en un lugar atractivo para el turismo internacional debido a la reciente construcción de una terminal de cruceros. Sin embargo, el desarrollo de este puerto se encuentra detenido hace varios años debido a persistentes problemas de sedimentación en su canal de acceso y dársenas. Debido a la obstrucción parcial del transporte de sedimentos que provoca la escollera Sur del puerto, el área costera se caracteriza por el avance de la línea de costa aguas arriba, el desarrollo de un banco de arena a través del canal de acceso y significativos procesos de erosión en las playas ubicadas al Norte del puerto. Los mecanismos responsables de estos procesos fueron evaluados mediante el Sistema de Modelación Morfológica MIKE 21/3 de malla flexible desarrollado por la empresa DHI. El modelo morfológico fue calibrado y validado mediante relevamientos batimétricos realizados en el entorno del acceso portuario. El modelo fue aplicado con una simulación a mediano plazo (tres años), con especial interés en la evaluación de la eficacia que tendría una obra de dragado para restablecer la profundidad de diseño del canal. Esta modelación morfológica permitió una mayor comprensión de los principales procesos hidrodinámicos y sedimentológicos que ocurren alrededor de la entrada del puerto, así como la obtención de información potencialmente útil para el diseño de estructuras y la planificación del dragado de mantenimiento. Se determinó que para las presentes condiciones hidrosedimentológicas el banco de arena se mueve hacia el canal de acceso con altas tasas de sedimentación, por lo cual requiere un mantenimiento regular, o la construcción de obras complementarias tales como trampas de sedimentos, espigones, la extensión de la Escollera Sur, etc. Desde el punto de vista de la reducción de la sedimentación, la eficacia de cualquier intervención debe ser verificada antes de su aplicación. En todos los casos, el transporte de sedimentos siempre será bloqueado, con lo cual debe considerarse el bypass artificial de arena con el fin de proteger las playas ubicadas al norte del puerto. [ABSTRACT FROM AUTHOR]

Manson, G.K.; Davidson-Arnott, R.G.D., and Ollerhead, J., 2016. Attenuation of wave energy by nearshore sea ice: Prince Edward Island, Canada. Sea ice is widely held to be decreasing in coastal waters where it is known to be effective in attenuating wave energy. This process is critical for understanding nearshore sediment transport and coastal change in ice-infested waters. We explore the attenuation of waves shoaling in nearshore ice using a simple attenuation model, hydrodynamic modelling, field studies, and daily charts of sea ice. The attenuation model is drawn from studies in deep water and modified for shallow water using field measurements. In a simple but common configuration where ice lies in a band onshore and waves enter from open water, the theory that wave energy decays exponentially as waves enter ice appears to hold true in shallow and deep water. The wave energy density in ice relates to the incoming wave energy density, attenuation distance, and an attenuation coefficient related to ice concentration and floe diameter. Much of the variability in measurements is explained by the theory, but substantial uncertainty remains. Prediction potential might be improved with higher resolution wave measurements and modelling, consideration of the rebuilding of attenuated waves in partial ice cover, and separate treatment of new ice. The adapted semiempirical theory is likely generally applicable to ice-infested coastal waters, but field studies in particular environments will be required to calibrate attenuation. [ABSTRACT FROM AUTHOR]

Dai, H.; Ye, M., and Niedoroda, A.W., 2015. A model for simulating barrier island geomorphologic responses to future storm and sea-level rise impacts. This paper presents the Barrier Island Profile (BIP) model, a new computer code developed to simulate barrier island morphological evolution over periods ranging between years and decades under the impacts of accelerated sea-level rise and long-term changes in the storm climate. The BIP model is a multiline model that represents the time-averaged dynamics of major barrier island features from front beach to backshore. Unique contributions of BIP to coastal modeling include a dynamic linking of interacting barrier island features and consideration of both future sea-level rise and storm climate impacts. The BIP model has the built-in capability of conducting Monte Carlo (MC) simulations to quantify predictive uncertainty caused by uncertainty in sea-level rise scenarios and storm parameters. For a series of barrier island cross-sections derived from the characteristics of Santa Rosa Island, Florida, BIP was used to evaluate their responses to random storm events and five potential accelerated rates of sea-level rise projected over a century. The MC simulations using BIP provide multiple realizations of possible barrier island morphologic responses and their statistics, such as mean and variance. The modeling results demonstrate that BIP is capable of simulating realistic patterns of barrier island profile evolution over the span of a century using relatively simple representations of time- and space-averaged processes with consideration of uncertainty of future climate impacts. [ABSTRACT FROM AUTHOR]

Burningham, H., French, J.R., 2014. Travelling forelands: complexities in drift and migration patterns. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 102-108, ISSN 0749-0208. Cuspate forelands have been described from a range of shorelines around the world, but in the majority of cases, the foreland maintains a constant position relative to the neighbouring shoreline. Here, we describe the contemporary geomorphology and historical evolution of a small cuspate foreland on the Suffolk coast, UK, which has been migrating northward for several centuries. Benacre Ness, a mixed sand and gravel sedimentary accumulation, is currently located at Kessingland, 5 km to the north of Benacre, from which it gained its name when adjacent to it in the 19th century. The foreland was previously called Covehithe Ness, having been adjacent to Covehithe (3 km south of Benacre) early in the 19th century. Previous sediment transport experiments and modelling studies have demonstrated a net southerly transport direction on this coastline, yet the foreland has continued to migrate northward over several centuries. Local reversals in sediment transport direction and rates are likely responsible for the northward migration of the foreland, but substantial changes in behaviour over the last 400 years suggest a close relationship between foreland dynamics and coastal configuration. [ABSTRACT FROM AUTHOR]

Combinations of storm surge and extreme waves may cause overtopping of coastal protection of structures, resulting in structural damage and flooding behind these structures. The high turbulence of the overtopping flow is an important factor for soil erosion and may be responsible for the destruction of levees during combined overtopping. The goal of this study was to investigate the turbulence and erosion characteristics of one levee strengthening technique, high-performance turf reinforcement mat, under combined wave overtopping and storm surge overflow. A three-dimensional hydrodynamic and sediment transport model known as ECOMSED has been calibrated and verified with overflow discharge and full-scale overtopping experimental results. The study simulated 41 storm surge overflow and combined overtopping cases with different freeboards and significant wave heights. Overtopping hydrodynamic flow, turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope under combined overtopping conditions were calculated. New equations for estimating turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope were developed. The equivalency of erosion rate under storm surge overflow and combined wave and surge overtopping are provided. The range of the application of these equations is discussed. [ABSTRACT FROM AUTHOR]

This study focuses on the role of clay on subsidence of Holocene sedimentary sequences in the northern Nile Delta. Proportions of clay in 1262 samples from 87 cores are much higher here than elsewhere in the delta and along the Nile in Egypt. The northern third of the delta lies at a low, near-horizontal elevation (~1 m above mean sea level), but clay content and total thickness of Holocene deposits in subsurface vary considerably in time and space. Greatest clay content (to >60%) and mud-rich thickness (to 47 m) are concentrated near Manzala lagoon. The volume of Nile water and sediment discharged annually on the delta diminished during the past two millennia as a result of climate change and intensified human activity. During the past two centuries, barrages and dams placed across the Nile and increased water diversion activities further reduced Nile flow and sediment delivery to the northern delta. Lowering at the coastal margin has also resulted from interplay of sediment compaction, regional sea-level rise, and intermittent readjustment of strata at depth. These events are ongoing, as indicated by increased erosion of extensive stretches of delta coast, salinization that affects large areas of agricultural land and groundwater, and major changes in recent sediment textural patterns as mapped in the present survey. Formerly dominant fluvial S-to-N transport during much of the Holocene has become distinctly shore parallel, recording landward shoreline advance and W-to-E sediment displacement along the delta margin. Implementing extensive coastal protective measures should take into account zones most prone to effects of subsidence, where (1) clay-rich subsurface sequences are thickest, (2) these strata are subject to high compaction rates, (3) sediment replenishment is insufficient, and (4) readjustment at depth of pre-Holocene sequences is continuing. These factors will cause the delta's NE and north-central sectors to experience continued significant surface lowering. [ABSTRACT FROM AUTHOR]

Large-scale construction of tourist infrastructure on beaches around the world is consistently linked to unwanted morphological changes that lead to coastal erosion. Dune destruction, alteration of sediment sources, and the rigidisation of the coastal system are known to be the main causes of erosive behaviour on many tourist beaches. To plan sound shoreline management strategies, detailed understanding of the sediment transport processes is necessary. The present contribution focuses on the main sediment transport processes that take place at Cancun, Mexico, a large (12 km) and highly developed tourist beach. High-resolution quarterly beach profile monitoring from September 2007 to June 2009 is used to calculate volumetric changes that are reasonably well explained by the spatial patterns of modelled sediment transport potential. This parameter was calculated using the wave propagation model WAPO of Universidad Nacional Autonoma de Mexico, which explicitly solves diffraction and reflection processes that are particularly important in systems with pronounced rocky headlands, such as the northern and southern ends of Cancun beach. Results show a dominance of northward longshore transport in most of the system, and an important transport divergence with consistent southward transport at the southern end. Cross-shore transport seems to dominate the middle-north section of the beach. This behaviour is consistent with recent advances in the understanding of wave circulation in embayed beaches. The method used here is considered a good approximation of sediment transport patterns when local (surf zone) morpho- and hydrodynamic data are absent or difficult to acquire. [ABSTRACT FROM AUTHOR]

Altomare, C., Gentile, G.M., 2013. An innovative methodology for the re-naturalization process of a shingle beach The gravel beach of Torre del Porto (Italy) was affected by a huge erosive phenomenon during the last 30 years. The causes which led to the erosion and the design lines through which to obtain the re-naturalization have been identified. Following a new methodological approach, the project consisted of entrusting assorted rubble stones with a proper weight to the area. Consequently the natural formation process can unfold again its effectiveness and the beach is recreated. The monitoring of the sediment transport was essential to provide the information about the correct results of prediction and analysis of the nourishment. The methodology, results and monitoring phases are described in this paper. [ABSTRACT FROM AUTHOR]

Petruzzelli, V., Gracia Garcia, V., Gironella i Cobos, F.X. and Petrillo, A.F., 2013. On the use of lightweight materials in small-scale mobile bed physical models. In this paper an evaluation of the morphodynamic response of different relatively common lightweight materials in small-scale physical models is presented. Results must serve to provide an overview of the various aspects likely to sensibly influence on sediments morphological response in small-scale tests and to determine the possible suitability of the low-density particles investigated for coastal modelling. Different granular materials, covering densities between 1150 kg/m3 and 2650 kg/m3 and median diameters from 0.07 mm to 1.5 mm have been selected to reproduce the experiments carried out in 1987 in the Groβen Wellen Kanal (Hannover, Germany). Tests have been performed at the Technical University of Bari (Bari, Italy) at scale 1:100 and at the Technical University of Catalonia (Barcelona, Spain) at scales ranging from 1:15 to 1:50, using irregular wave conditions and geometries based on Froude scaling. An analysis of the erosion and deposition volumes, the shoreline evolution and the beach profile slope has been done. Results show different mobility rates and beach profile morphodynamics depending on particles intrinsic characteristics, demonstrating that for lightweight materials not only settling velocity is paramount to determine particles suitability and morphodynamic response. Finally, a comparison between the morphological evolutions of the models and the prototype moving along the beach profile cross-section is presented. [ABSTRACT FROM AUTHOR]

Umeda, S., 2013. Scour process around monopiles during various phases of sea storms An understanding of scour processes during the passage of sea storms is particularly important for the design of structures and the development of effective scour protection works. This study investigates the scour process at a slender monopile during various phases of a storm to give a better understanding of scour and backfilling mechanisms. Laboratory experiments were carried out to simulate the scouring effect at a pile by a storm consisting of a succession of seven phases of irregular waves. Detailed examinations were conducted to explore variations in the scour depth and bed topography. It turns out that scour patterns resulting from irregular waves can be characterized using the Keulegan-Carpenter number and the Shields parameter ( KC1/3, θ1/3), which require significant near-bottom velocities. The scour process during a heavy storm consists of four main phases: (1) no bed deformation, (2) accretion, (3) erosion, and (4) backfilling. The amount of scouring increases as the order of the phase increased during a storm. The scour during phase (2), accretion, is in the transient condition between clear-water scour and live-bed scour. The scour in phase (3), erosion, is distinguished by live-bed scour, horseshoe vortices, vortex shedding and cone-shaped scour holes with vortex ripples. The influence of backfilling, phase (4), as a storm decreases in intensity, has a significant effect on the scour depth around the perimeter of the pile. The scour depth at the end of the event is much lower than the maximum scour depth during the event. However, backfilling of the scour hole makes only a weak recovery in total sediment volume around the pile, because the backfilling is confined almost exclusively to the neighborhood of the pile. [ABSTRACT FROM AUTHOR]

Garcin, M., Baills. A., Le Cozannet, G., Bulteau, T., Auboin, A-L., Sauter, J., 2013. Pluri-decadal impact of mining activities on coastline mobility of estuaries of New Caledonia (South Pacific) This work aims at analysing the relative impact of sedimentary supply by rivers versus the effect of sea level rise and other processes over the last 5 decades of some representative coastal stretches of New Caledonia (South Pacific Ocean). The study of twelve coastal estuarine stretches has shown erosion rates ranging from −1.8m/y to accretion rates up to 5.5m/y over the last 50 years. During this time, the climate component of sea level rise has been evaluated around 0.5mm/y in Nouméa and can be considered identical on the studied island. Vertical movements affecting New Caledonia are suspected to be different between western and eastern parts of the island. Nevertheless, in areas with homogeneous vertical movement, the coastal stretches studied show various evolution rates. The analysis of accreting estuarine coastal areas shows that this evolution is linked to sedimentary supply from rivers. On New Caledonia Island, the creation of bare soils by nickel mining during the last 50 years has increased erosion processes on the watersheds and the solid discharge of the rivers. The study shows a strong correlation between the percentage of bare soil surfaces (up to 3.7 % of the watershed surface) generated by nickel mining and the coastline evolution rate (from −2m/y to +4m/y) around the estuaries of each watershed. Therefore, mining activity on watersheds is suspected to have been the major forcing factor of recent coastal changes during the last fifty years. [ABSTRACT FROM AUTHOR]

Devastating tsunami waves can mobilize a substantial amount of coastal sediments and change the coastal morphology considerably. In this study, laboratory experiments were performed in a wave flume to investigate the changes of beach profile and mean grain size caused by tsunami-like waves that have a front similar to that of a solitary wave and an undulating tail following the wave front. A composite slope was constructed using a mixture of two sizes of sand. In addition to recording the wave rush-up and rush-down processes using video cameras, measurements were also made on water surface elevation, bed profile and the final size distribution of the sand mixture for three water depths. The results showed that sand suspension and erosion were caused mainly by sheet flows when water retreats from the beach, whereas the offshore sandbars, composed mainly of coarser sand, formed mainly from the run-down jumps caused by the collapsing of retreating water with waves in the undulating tail. The findings of this study have the potential to assist researchers in understanding nearshore tsunami flows from tsunami deposits. [ABSTRACT FROM AUTHOR]

Macrotidal beaches are scattered in the west coast of Korea mostly in small embayments of the ria-type coastline and islands. In contrast to well-known tidal flats, these beaches have been little studied from the hydromorphologic viewpoint. Byunsan Beach was chosen to investigate beach processes affected by winter monsoon, which creates strong waves and wind-generated currents. The multiyear (2005-2008) profiling of the beach, together with the intensive sampling of surface sediments, provided the details of morphologic characteristics of the beach. Deep water winter wave characteristics were based on the measurements of an offshore buoy. A benthic tripod was deployed on the beach to observe waves, currents, and suspended sediments during a winter storm. The estimated morphodynamic parameters suggest that Byunsan Beach be classified as an ultradissipative state during winter. The tendency of grain size toward systematically fining seaward could be explained by the lateral displacements across the beach of swash and surf zones owing to a high tidal range. In addition, the tripod observations show that a storm readily generated offshore return flows capable of considerable beach erosion. The storm waves also significantly contributed to the erosion. This may reflect that the macrotidal, open beaches in the west coast of Korea are seasonally susceptible to pronounced erosion by winter monsoon. The results of this study may be useful for evaluating man-made environmental impacts caused largely by seawalls and dykes on the natural beach state intrinsic to the west coast of Korea. [ABSTRACT FROM AUTHOR]

The Netherlands is a low-lying country, where approximately 27 percent of the territory is located below mean sea level and 55 percent is prone to flooding. Protection against flooding is traditionally the primary objective of coastal policy in the Netherlands. However, since 1990 coastal policy has been subject to a number of modifications, and new objectives have been added to cope with the structural erosion problems of the Dutch coast. To fulfil these new objectives, the yearly volumes of sand for nourishment have been constantly increasing. Even higher volumes will be necessary in the future due to more severe sea level rise scenarios predicted. In this paper, sand volumes in the coastal area were analysed in combination with numerical modelling results of the sediment transport along the entire coast, to assess the effectiveness of the current nourishment policy, in the short and long term. One reference scenario of the current situation and one long-term prediction, including nourishment and sea level rise, were simulated. The results of this analysis show that nourishment has been successful in coping with the past erosion problems. Furthermore, sand volumes in the upper shoreface are now increasing, creating an additional buffer of sand, which might be needed in the future, as shown by the future scenario. [ABSTRACT FROM AUTHOR]

St. Augustine Inlet is located on the NE coast of Florida, connecting the Atlantic Ocean to the Tolomato and Matanzas rivers. The inlet is unique because it was relocated in the 1940s, resulting in considerable perturbations to the adjacent coastal system, especially the downdrift (southern) shoreline. The relatively low, permeable, and short north jet has allowed sediment to move around, through, and over the jetty, resulting in deposits on the interior lagoon/bay and on the ebb shoal system. Since 2001, dredging has occurred on the ebb shoal and bypassed to the downdrift side of the inlet on St. Augustine Beach. At present, dredging and bypassing have occurred on an irregular schedule, although questions remain about what a reasonable schedule would be to prevent excessive problems on both the updrift and downdrift beaches. This article presents an evaluation of a potential approach for use in addressing the dredging and bypassing schedules to assess how various intervals of dredging/bypassing can affect an idealized downdrift beach having the same net sand transport as that near the St. Augustine Inlet. [ABSTRACT FROM AUTHOR]

The present contribution aims to provide an insight into the sediment dynamics of the Bay of Marseille (BoM), France, an area characterised by a mostly rocky, steep-sloped, and protected shoreline. In terms of sediment composition, the northern part of the study area is dominated by fines, whereas sands of mean grain size 0.2 , d50 , 1 mm occur at most other locations. Posidonia oceanica meadows occupy many nearshore areas. Critical bed-shear stress was determined through tests in a unidirectional flume using 15 natural cores. Measured values ranged from 0.04 N/m2 to 0.46 N/m2 and were expressed as a function of the logarithm of d50. Mud content had no observable effect on sediment cohesion, whereas a weak positive trend between critical shear stress and clay content was discerned. Autonomous benthic stations (Acoustic Doppler Current Profiler/Conductivity, Temperature, Depth/Turbidity/ALTUS Data Collection System) were deployed for periods of 2-3 months, and several suspension and erosion events were identified for significant wave heights exceeding 1.5 m. Grain-size trends showed that the protected BoM appeared to favour accumulation of sediments advected from the surrounding areas. The southern sector of the BoM was found to be the area with the highest sediment agitation and erosion rates but with weak transport trends. The northern sector, exposed to dominant SW waves, was shown to be the second most active area in terms of sediment dynamics, whereas the several Posidonia oceanica meadows and sheltered locations along the study area appeared to be possible sediment sinks. The latter included locations close to port installations and the western part of the Cortiou area, known to have water quality issues, which, according to the present findings, are linked to low sediment mobility and/or dispersion of pollutants. [ABSTRACT FROM AUTHOR]

This paper describes a methodology for modeling long-term evolution of multiple inlet systems in southwest and central Florida. The paper discusses the application of this methodology to two inlets within Sarasota Bay system in southwest Florida. The case studies of Longboat Pass and Venice Inlet demonstrate the importance of considering large temporal and spatial scales in multiple inlet systems. The results describe the evolution of Longboat Pass and Venice Inlet from 1880 to present. The analysis begins with natural conditions that existed before dredging or inlet modifications and investigates how inlet evolution can be influenced by navigation improvements or mining of ebb shoals for beach nourishment. [ABSTRACT FROM AUTHOR]

This paper examines the short-term evolution of a cuspate foreland with diminished sediment supply in the western Gulf of St. Lawrence. Topographic light detection and ranging and airborne light detection and ranging bathymetry are used to provide an overall analysis of the foreland system at Paspébiac, Quebec, including high-resolution digital morphology of combined subaerial and subaqueous components, between 2003 and 2006. Results indicate large differences in coastal stability around the foreland. The western barrier exhibits a stable shoreline (net change = +0.3 m·y-1), a moderate beach slope (0.12-0.18), and no subtidal bar system. The morphodynamic response in this sector is influenced by jetties and alongshore variability and is related to beach planform readjustments to varying wave conditions. The eastern barrier has higher wave exposure, high erosion rates (<6.7 m·y-1), wave washover, and an intermediate barred-beach profile, with higher beach slopes (β 5 0.16-0.24). The alongshore variability is controlled, at length scales of about 500 to 700 m, by differences in relaxation time between distal and proximal sections of the foreland. At shorter length scales (∼100-500 m), alongshore variation is related to inner bar morphology, higher erosion rates being observed near rip channels or in the absence of an inner bar. Sand transport patterns reflect wave energy and approach and include a reversal in transport direction along the eastern barrier under storm waves from the SW. We show that, under declining sediment supply, sediment is being lost to a shoal and deep water off the tip of the foreland and erosion on the eastern barrier is not compensated by the slow accretion on the western side of the point. [ABSTRACT FROM AUTHOR]

Sediment transport between the emerged land masses and deep marine basins is a fundamental process that affects the exploitation of resources and protection of the environment and its ecosystems. Sediment transport models on the continental shelf are often very complex and subject to semiempirical or empirical equilibrium transport equations that relate sediment fluxes and turbulence to physical properties such as velocity, depth, and characteristic bed-load sediment particle sizes. In engineering applications, errors in these physical properties affect the accuracy of the sediment fluxes. The present analysis details the importance of physical properties to the bed-load fluxes and suggests which parameters have more influence on the final result by providing insight into the relative strengths, weaknesses, and limitations of all the selected 52 bed-load equations for noncohesive particles (sand and gravel are treated separately). Various parameters were first investigated individually to pinpoint the key physical properties that control the errors. Because the existence of strong nonlinearity in most bed-load transport equations precludes analytical approaches, the multilinear regression (MLR) method was used to validate this analysis. Several graphs are presented to emphasize the influencing effect of those parameters that were either used directly or embedded in these equations. The most significant parameters that directly influence the sand particles are θ, ds, and vav, and the embedded parameters are sfτo, θds, and Sfθ. On the other hand, for gravel particles, the most significant parameters are θ, ds, and θcr and qs*, Sfθ, and sfτo, respectively. [ABSTRACT FROM AUTHOR]

In recent years, the exploitation of marine aggregates is increasing. As an example, on the Belgian continental shelf-one particular sandbank (the Kwinte Bank) is exploited extensively; this has led to the creation of a 5 m deep depression along its central part. In the present contribution, the influence of these bathymetric changes, on erosion and sedimentation patterns are studied, using numerical modelling, in order to obtain an initial impression of the effect of such intense sand extraction on the stability of the sandbank. Different numerical models are utilised, two-dimensional and three-dimensional hydrodynamic models have been used to derive currents, whilst third generation wave models have been used to simulate the waves. Two different models are presented, which calculate the total load sediment transport as a function of the local currents and waves. These models have been used to investigate the erosional and depositional patterns. The use of two different sediment transport models has some advantages, since the results of sediment transport models are still subject to some important uncertainties. The hydrodynamic model results are validated using ADCP current data, confirming the good performance of the models. Likewise the wave models provide good results, comparing their results with data from a buoy. The sediment transport model results were compared to the residual transport patterns, derived from the asymmetry of dunes. The results obtained seem to he in general agreement with these observations. The numerical models are used to simulate the response of the sediment transport to extensive sand extraction from the sandbank. One `worst-case' scenario and two more realistic scenarios were simulated, whilst the effect of these bathymetric changes on sediment transport was studied. The results show that the intense sand extraction does not seem to influence extensively the stability of the sandbank, but that, as a consequence, there is less erosion and deposition. The model results show, for all of the scenarios, a small amount of deposition on the top of the sandbank; this could be an indication of a regeneration mechanism. A trench, created perpendicular to the crest of the sandbank, could be slowly refilled again. The time-scale of this regeneration and the influence of storms remain uncertain. Although the main emphasis of the paper relates to tidal forcing, a brief discussion is included on the influence of wave action, on sediment transport. [ABSTRACT FROM AUTHOR]

Earthen levees are designed for little wave overtopping during a design storm, but excessive overtopping and overflow can occur due to the combined effects of an extreme storm, sea level rise, and land subsidence. The transition from little wave overtopping to excessive wave overtopping and overflow on an impermeable smooth levee is examined in waveflume experiments consisting of 107 tests. Existing empirical formulas are shown to be applicable to the cases of excessive wave overtopping and overflow in these tests. A numerical model based on time-averaged continuity, momentum, and wave action equations is connected to a new probabilistic model for the wet-and-dry zone, in order to predict the cross-shore variations of the mean and standard deviation of the free surface elevation and depth-averaged fluid velocity from outside the surf zone to the inner slope of the levee. The new model is calibrated to predict the measured overtopping and overflow rates within a factor of about two. The agreement is also shown to be similar for the water depths and velocities measured in the wet-and-dry zone on six different structures in 100 Dutch tests. The developed hydrodynamic model is coupled with new formulas for suspended-sand and bedload transport rates to predict dune erosion and overwash. The coupled model is compared with two small-scale tests on dune erosion with minor overwash, three large-scale tests on dune erosion, and field data on dune erosion and overwash due to severe storms lasting several days. The overwashed-dune profiles are predicted reasonably well, but the coupled model will need to be evaluated using measurements of wave overtopping and overwash rates. [ABSTRACT FROM AUTHOR]

The dataset from the SUPERTANK laboratory experiment was analyzed to examine wave runup and the corresponding upper limit of beach-profile change. Thirty SUPERTANK runs were investigated that included both erosional and accretionary wave conditions with random and monochromatic waves. The upper limit of beach change UL was found to approximately equal the vertical excursion of total wave runup, Rtw. An exception was runs where beach or dune scarps were produced, which substantially limit the uprush of swash motion to produce a much reduced total runup. Based on the SUPERTANK dataset, the vertical extent of wave runup above mean water level on a beach without scarp formation was found to approximately equal the significant breaking wave height, Hbs. Therefore, a new and simple relation Rtw = Hbs is proposed. The linear relationship between total runup and breaking wave height is supported by a conceptual derivation. In addition, the relation is extended to UL = Rtw = Hbs to approximate the upper limit of beach change. This formula accurately reproduced the measured upper limit of beach change from the three-dimensional experiments in the Corps' large-scale sediment transport facility. For the studied laboratory cases, predictions of wave runup were not improved by including a slope-dependent surf-similarity parameter. The limit of wave runup was substantially less for monochromatic waves than for random waves, attributed to absence of lowfrequency motion. [ABSTRACT FROM AUTHOR]

The evolution of the coast of Hawke's Bay, New Zealand, and its erosion problems have been governed by multiple factors, including its tectonic setting with an earthquake in 1931 that altered land elevations along its shore, ranging from a 2-m uplift at its north end to 1-m subsidence at its south. Human environmental impacts have also been important, including the deforestation of the watersheds of rivers and the mining of gravel and sand from their channels, having decreased the sediment supplies to the beaches. Significant erosion has occurred at the south end of the Hawke's Bay shore, attributed in part to its subsidence in 1931, together with the net northward longshore transport of the beach sediment that is greater than the volumes being supplied by the rivers, the beach-sediment budget being significantly ''in the red.'' Midway along the Bay's shore, the construction of the Port of Napier's breakwater in 1887-90, extending seaward from the Buff Hill headland within that city, is interpreted by some investigators to have been the cause of the erosion experienced at Westshore, a development located immediately north of the breakwater. The assumption has been that this erosion was the result of the breakwater having blocked the northward longshore transport of sediment that formerly had bypassed Bluff Hill, this being an example of down-drift beach erosion. However, a reexamination of the history of the Port's development, the resulting shoreline changes, differences in beach gravels on the shores north and south of Bluff Hill, as well as other evidence, support the conclusion that the breakwater was not the cause of the erosion; instead, the impacts to Westshore at the time of the breakwater construction can be attributed primarily to a series of major storms, which produced erosion at a number of sites along the Hawke's Bay shore. There has been minimal erosion at Westshore since the completion of the breakwater a century ago, its northward extending arm acting to shelter the development from the waves of major storms. Investigations by coastal scientists and engineers of the Hawke's Bay coast, together with a comprehensive beachsurvey monitoring program, support its sound management based on an understanding of the multiple factors that are important to its responses during storms, and to its long-term changes. [ABSTRACT FROM AUTHOR]

The coastline of Hai Hau District, located on the northeast coast of Vietnam with about 30 km of shoreline, is chronically eroding. Previous studies have tried to highlight the main causes of the erosion along this coastline, and several hypotheses exist. To examine the hypothesis that gradients in the longshore sediment transport rate and cross-shore fine sediment lost offshore are the main causes generating the serius erosion at Hai Hau Beach, a newly developed numerical model of shoreline change based on the one-line theory was applied and compared with data. Sea dike segments, reinforced by stones and mortar, were modeled using a seawall boundary condition, and the sediment continuity equation was modified to take into account the offshore transport of fine-grained sediment. The simulated shorelines agreed well with the measured shorelines, both for the calibration and validation periods. The calculated sediment budget shows that the net sediment transport is in the southward direction and that a large amount of finegrained sediment is lost into deep water. These two sinks of sediment are believed to be the main causes of the serious erosion at Hai Hau Beach. [ABSTRACT FROM AUTHOR]

The climates of wave-related nearshore processes important to coastal erosion have been investigated based on analyses of wave data measured at six sites along the Mediterranean coast of Egypt, spanning 0.92 to 5.25 years. Wave climates along this 900-km coastline are nearly identical in their significant wave heights, periods, and directions. The evaluated nearshore processes that depend on combinations of deep-water wave heights and periods are found to respond to seasonal changes in wave conditions. These processes include the climates of breaker heights on beaches, beach face slopes, the morphodynamic classification of beaches, swash runup elevations induced by storm waves, the depth of closure of beach profiles, and calculated sediment transport rates. The seasonal changes observed in the wave-related nearshore processes are ultimately responsible for the episodic morphologic changes identified in the beach and seabed environments of the Nile Delta. The largest storm waves measured during the study period had deep-water significant wave heights of 7.7 and 6.8 m at the Dabba and Abu Qir coastlines, respectively. [ABSTRACT FROM AUTHOR]

Ensemble-averaged suspended sediment concentrations (SSC) and transport from the swash zone of a high-energy beach are investigated with respect to the time-averaged setup level obtained from calibrated video records. Ensemble-averaged data indicate variability in SSC between both uprush and backwash during rising and falling tides. Mean ebb-tide SSC exceeds mean flood-tide SSC during both the uprush (by 28-34%) and backwash (by up to 25%). Suspended sediment concentration also varies between swash phases over a tidal cycle with mean uprush SSC exceeding mean backwash SSC by 46% to 108% depending on tidal level, with a general percentage decrease during the falling tide. The net ensemble-averaged transport (velocity-SSC product) magnitude displays a decreasing trend from roughly 30 to 20 kg m-1 during the rising tide and from roughly 45 to 15 kg m-1 during the falling tide that cannot be explained based on the percentage of foreshore immersion (water depth) alone. Thus, relative tidal level (cross-shore instrument position within the swash zone) and the phase of tide (rising or falling) within the swash zone play an important role in determining the magnitude of sediment suspension and transport. [ABSTRACT FROM AUTHOR]

Previous studies carried out in the study area near Port Said, Egypt, concentrated mainly on analyzing the measured and calculated longshore sediment transport data and making predictions by modeling works. Few studies have conducted statistical and uncertainty analyses. In the first stage of this research, wave-time series from altimeter measurements were used for a domain of 50 km in length offshore and 25 km in width alongshore. Wave nearshore transformation analysis was carried out using the SWAN model. The transformed wave data were used for preliminary evaluations of littoral drift. Three formulae were used and were compared with the available target values. As a result, two equations provided suitable correction factors. Applying these corrections, the average values of the evaluations were determined and fit well with the target values. In this stage of the research, statistical and uncertainty analysis for occurrence probabilities were carefully carried out for these evaluations. The main statistical parameters and the representative occurrence-probability density functions were determined. This investigation showed the importance of concentration on both NNW and NW wave propagation as dominant in the evaluations carried out. The quantity of longshore transport associated with minimum uncertainty in occurrence probability was also determined. The random bootstrap trends for both mean and standard deviation measurements were determined for both summer and winter seasons. Bias trends for longshore transport during the four annual seasons were also determined. The results of these analyses will be beneficial for understanding seasonal changes in littoral drift in this region. [ABSTRACT FROM AUTHOR]

Barrier-island chains worldwide are undergoing substantial changes, and their futures remain uncertain. An historical analysis of a barrier-island chain in the north-central Gulf of Mexico shows that the Mississippi barriers are undergoing rapid systematic land loss and translocation associated with: (1) unequal lateral transfer of sand related to greater updrift erosion compared to downdrift deposition; (2) barrier narrowing resulting from simultaneous erosion of shores along the Gulf and Mississippi Sound; and (3) barrier segmentation related to storm breaching. Dauphin Island, Alabama, is also losing land for some of the same reasons as it gradually migrates landward. The principal causes of land loss are frequent intense storms, a relative rise in sea level, and a sediment-budget deficit. Considering the predicted trends for storms and sea level related to global warming, it is certain that the Mississippi-Alabama (MS-AL) barrier islands will continue to lose land area at a rapid rate unless the trend of at least one causal factor reverses. Historical land-loss trends and engineering records show that progressive increases in land-loss rate correlate with nearly simultaneous deepening of channels dredged across the outer bars of the three tidal inlets maintained for deep-draft shipping. This correlation indicates that channel-maintenance activities along the MS-AL barriers have impacted the sediment budget by disrupting the alongshore sediment transport system and progressively reducing sand supply. Direct management of this causal factor can be accomplished by strategically placing dredged sediment where adjacent barrier-island shores will receive it for island nourishment and rebuilding. [ABSTRACT FROM AUTHOR]

Muin, M., 2021. Sediment dispersion modeling of a non-orthogonal boundary fitted technique: Mangrove reclamation to protect cliff erosion in Bintuni Bay, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 544–548. Coconut Creek (Florida), ISSN 0749-0208. Bintuni Bay is a semi-closed bay located in West Papua Province, Indonesia. The facility of Tangguh LNG Project was faced serious problems due to erosion along the cliff. It was decided that reclamation is the best solution. Mangrove trees are planted in the reclamation area to reduce the wave. The reclamation was designed until one meter below highest water spring to allow seawater to flow in and out through the inlet/outlet. This paper presents and discusses simulations for several options of reclamation layout, inlet/outlet, during and after reclamation. MuSed3D, the 3D ocean hydrodynamics and sediment transport model using non-orthogonal boundary fitted technique, was employed to conduct the simulation. [ABSTRACT FROM AUTHOR]

A multilevel breadth-averaged numerical model has been developed and applied it to the Gulf of Khambhat to study the tidal circulation, salinity, and suspended sediment transport. The model is fully nonlinear and uses a semiexplicit finite difference scheme to solve mass, momentum, and advection diffusion equations in a vertical plane. A turbulent kinetic-energy scheme is used to parameterize the vertical transfer of momentum, salinity, and suspended sediments. The model is forced by prescribing the tidal elevations along the open boundary of the analysis region. The tide in the gulf is mainly represented in the model by the semidiurnal M2 constituent. A freshwater discharge from the landward end is also considered for this study. The erosion and deposition are computed by empirically developed source and sink terms in the suspended sediment equation. Numerical experiments were carried out to simulate the tidal circulation, salinity intrusion, and suspended sediment transport in the gulf region. The computed M2 tide and salinity at two different sets of coastal stations were validated with the available observations. [ABSTRACT FROM AUTHOR]

The method of labeled natural sand particles was used to study sediment transport along the central Mediterranean coast of Israel. Six portions of 300 kg each were tagged with various fluorescent colors, and distributed at six different locations in the vicinity of the Herzliya Marina. The tagged sand was scattered at the end of autumn, and sampled three times during the winter. Sampling was interrupted in mid-January because of unexpected dredging at the marina canal entrance. The samples were analyzed at the Yigal Allon Kinneret Limnological Laboratory. The wave climate during that time was analyzed using wave data from Ashdod (40 km south). Wave directions measured in Ashdod were corrected to make them applicable to the Herzliya coast, in accordance with suggested directional shift values. Seven wave storms with significant wave heights of over 2.5 m were observed. Two of them clearly indicate a dominant direction from the southwest and two others from the northwest. However, the time durations and the relative angles between the wave directions and the orthogonal to the coast of the storms propagating from the southwest are essentially larger than those arriving from the northwest. The following results were noted: (i) The drift of tagged sand particles correlated to longshore sediment transport at all depths was in a northern direction throughout the field experiment. The longest distance of transport was 5 km over a period of 36 days. (ii) ''Onshore'' sediment transport was present; sand from 15 m depth was found at 8 m depth. (iii) The cross-shore sediment transport carried sand to a depth of 8 m, but no colored sand from shallow water (2-4 m) was found deeper than 8 m. (iv) Although sedimentation at the marina entrance during the experiment was high, only small amounts of tagged sand were found at the entrance. (v) Findings of tagged sand showed the main area of sedimentation to be along the marina's main breakwater. [ABSTRACT FROM AUTHOR]

The construction of a deepwater harbour jetty near Nouakchott, the capital city of Mauritania, significantly modified the southward longshore sand transport, causing severe shoreline recession. The UNIBEST numerical model was used to study the actual impact of this infrastructure and assess the future shoreline evolution. The results, validated by field measurements, indicate that the shoreline evolution rate has undergone a 10-fold increase after harbour construction, with significant accretion to the north and severe erosion to the south of the harbour. Such findings are well documented by past and present observations. Model predictions also suggest that erosion south of the harbour may lead in the near future to inundation of parts of Nouakchott lying below sea level. Finally, this type of numerical hindcast-forecast approach, used for a simple sediment transport case, is useful for the prediction of future shoreline morphodynamic evolution, and may be a valuable surrogate for more expensive physical hydraulic modeling. [ABSTRACT FROM AUTHOR]

Field measurements of tidal current velocities are used to infer sediment transport characteristics in the lower section of a large, tidally dominated estuarine system at Whangarei Harbour, New Zealand. Recent (2002) developments at the harbour entrance included a 32.6 ha intertidal reclamation and a 31.8 ha dredged turning basin. Residual distance vectors indicate that the postdevelopment, large-scale pattern of sediment transport dynamics remains consistent. Minor, localised modification of transport potentials has been observed immediately adjacent to the developments, however. These modifications include a slight realignment of current flows near the reclamation wall and some leakage from a previously identified transport loop near the dredged basin. The potential for scour is identified along the eastern margin of the dredged basin, which could act to remove material moving downslope into the basin from its western edge. These data are consistent with numerical model results that predicted minimal consequences resulting from the developments. Lower harbour sediment dynamics are consistent with established patterns for tide-dominated inlets, with separation of the channel into areas of ebb and flood dominance, and typical transport patterns over the flood tidal delta. Broad-scale inlet geomorphology has been maintained, which is consistent with other dredged tide-dominated inlets. [ABSTRACT FROM AUTHOR]

The São Francisco River mouth is undergoing a severe erosional process that has caused the destruction of a village and the partial immersion of a lighthouse constructed in 1856. The present work comprises an historic time evaluation of this phenomenon based on the analysis of the sediment dispersion patterns caused by waves along three distinct shoreline traces. For this, we define a wave climate model based on the construction of refraction diagrams, which are assumed to be valid for the three shorelines. The resulting sediment transport patterns obtained by numerical modeling from the refraction diagrams--taking into account the angle of approach and the wave height along the coast--allow us to establish a first-order correlation between coastal dynamics and erosion phenomenon. The results also suggest that a permanent reduction in the solid river discharge, in response to the construction of large dams, probably will have two direct consequences in the river mouth region: (i) a chronic shoreline erosion downdrift of the mouth and (ii) a progressive deflection of the mouth in the downdrift direction. [ABSTRACT FROM AUTHOR]

The regeneration of 1100 ha of derelict industrial land to the south of Cardiff included the construction of the 1.1km-long Cardiff Bay Barrage (completed November 1999), which impounded two major South Wales rivers. A 160 m groyned beach, composed of four groynes and three bays, adjacent to and seaward of the barrage breakwater was monitored between September 1997 and September 2002 to assess pre- and postconstruction beach evolution. Overall, mean beach levels increased throughout the five-year period, resulting in a net gain of beach covering equivalent to 818.8 m² (1800 tonnes). After barrage completion, both longshore and cross-shore gradients became less volatile and increased beach levels in the bay nearest the breakwater, prevented tidal action and erosion at the cliff toe. This was a significant change from initial conditions that was verified by parametric and nonparametric tests at the 99% confidence level. Regression analysis determined that there were significant temporal relationships. Spatial analysis identified two highly significant longshore trends with respect to distance from the breakwater and showed that this influence decreased with distance. More than 72 m from the breakwater, the regression equation (R² = 96% ) modelled a trend of falling beach levels caused by net sediment transport. Conversely, from 72 m to the breakwater, beach levels increased at a rate greater than twice the Fall in the previous section (R² = 92% ). These trends were further supported by significantly greater level differences across the second groyne. Impacts of temporal and spatial trends, especially subsequent to barrage completion, were evidenced by the change in beach morphology and similar contour orientation in all three bays. Models were developed and proposed as management tools to identify potential changes in coastal processes, as well as the rate of change of the barrage's upstream influence with respect to net sediment flow. Groyne removal was suggested to provide recreational beach space. [ABSTRACT FROM AUTHOR]

In 1997, the effects of severe erosion along the Penarth, Wales, UK, foreshore became apparent when the beach surface fell to critical levels. A 240 m length of beach, bounded by a slipway, sea wall, and pier, was surveyed each September and April between 1997 and 2002 to assess summer and winter changes Results in September 1997 showed that sediment transport was southerly in direction, whilst by September 2062, there had been a consistent return to the traditionally accepted south-to-north longshore drift, verified by significant differences in longshore gradients (t=2. 664; degrees of freedom [DF] =6; p < 0. 05). Analysis of changes in beach morphology has shown that erosion induced a southerly movement of beach contours, and a northerly movement was produced by accretion. Foreshore analysis has resulted in important regression models representing the variation of the shoreline indicator mean high water (MHW) with both shoreline position (mean beach level) and gain/loss of beach material The crossshore position of the depth of closure (DoC) was 50 m seaward of the survey line, at a water depth of 5. 5 m. Results from analyses of cross-shore profiles verified temporal variations in back beach level with little variation beyond the DoC. Furthermore, there was significant correlation between the two shoreline indicators, MHW and DoC (84%). This correlation, combined with a derived equation for a management response parameter (MRP = 17. 035 + tan-1 (x14- x6)/240[°]), produced simple tools to rapidly assess beach health. Results were compared with past data for interpretation of significance, and management strategies based on tabulated MRP values are suggested. A general {brm of this equation has been developed for testing at other beach locations, which should have significance from worldwide beach management. [ABSTRACT FROM AUTHOR]

Since the beginning of the 1980s, several methods for the study of sediment transport dynamics have emerged that are based on the distribution of granulometric parameters. These studies are limited to current sediments of three basic environments: fluvial, coastal, and estuary, for which the objective is to determine the direction of global transport and delineate specific areas of deposition, erosion, or equilibrium. These studies show a growing demand for planning mechanisms that find sailing areas that take advantage of wave energy in estuaries. This work is related, specifically, to sedimentary transport for aqueous flow in estuaries and near-coast areas. In this paper, we present an alternative analysis of sediment transport dynamics that is based on a 2D interpolation procedure that takes into account the vectorial kriging methodology, which considers the spatial characterisation of a directional stochastic process in the interpolation of the vector azimuth. For example, to study sediment transport dynamics, we used the directional kriging approach to two groups of granulometric data sets: one belonging to the Schelde River, situated between Holland and Belgium, and the other belonging to the Itanhém River estuary in the south of Bahia, Brazil. An advantage of this method is the possible control of the prediction errors of the transport direction. The results obtained throughout this robust method are quite satisfactory compared with the energetic conditions observed in situ. [ABSTRACT FROM AUTHOR]

High-frequency measurements of airflow from ultrasonic anemometers and time-averaged cup anemometer profiles were taken during an oblique alongshore sand-transporting event (6.7 m/s) over a vegetated foredune in May 2002 as part of a larger study on the sedimentary dynamics of a beach-dune complex in Greenwich Dunes, Prince Edward Island National Park, Canada. Local flow and sand transport pathways deviated significantly from the regional wind because of topographic steering of oblique alongshore airflow on the beach back toward the foredune in the backshore. Flow decelerated on the lower seaward slope of the foredune because of flow stagnation and vegetation-induced roughness effects. On the upper seaward slope, flow veered crest-parallel because of secondary flow effects, including potential flow reversal, acceleration, and interaction with faster regional flow. An inflection point in velocity profiles indicates a momentum sink at plant canopy height, and above this height exists a distinct shear layer. Flow acceleration occurs only on the upper slope above the plant canopy as the shear layer intensifies. Flow steadiness, as indicated by the coefficient of variation in horizontal (U) and vertical (W) velocity, also declines up the seaward slope, in contrast to measurements of flow over unvegetated dunes, perhaps because of increasing vegetation-induced drag and turbulence. Gusting and vertical bursting was evident as honami motion in the beachgrass and was responsible for maintaining intermittent saltation into the foredune. Temporal correlations exist between U, W, and flow angle. As flow shifted onshore, both U and W increased because of enhanced topographic forcing and increased vertical lift on the lower seaward slope, whereas when flow shifted alongshore, U and W declined because of reduced forcing and acceleration effects because the dune is effectively less steep to flow. Although these dunes align well with the vector of the regional resultant sediment drift potential, sand transport pathways followed local flow vectors of varying magnitude and direction. Offshore to oblique alongshore winds are typical of the summer wind regime, and, although frequently incompetent, they contribute to dune maintenance by cycling sand to the backshore for incipient foredune growth, scarp infilling, or both. To date, the role of secondary flows under alongshore winds in foredune morphodynamics has not been well documented. [ABSTRACT FROM AUTHOR]

Contemporary three-dimensional numerical sediment transport models are often computationally expensive because of their complexity and thus a compromise must be struck between accurately modeling sediment transport and the number of effective sediment grain (particle) size classes to represent in such a model. The Environmental Fluid Dynamics Code (EFDC) was used to simulate the experimental results of previous researchers who investigated sediment erosion and gradation around a 180° bend subject to transient flow. The EFDC model was first calibrated using the eight distinct particle size classes reported in the physical experiment to find the best erosion formulations to use. Once the best erosion formulations and parameters were ascertained, numerical simulations were carried out for each experimental run using a single effective particle size. Four techniques for evaluating the effective particle size were investigated. Each procedure yields comparable effective particle sizes within a factor of 1.5 of the others. Model results indicate that particle size as determined by the weighted critical shear velocity most faithfully reproduced the experimental results for erosion and deposition depths. Subsequently, model runs were conducted with different numbers of effective particle size classes to determine the optimal number that yields an accurate estimate for noncohesive sediment transport. Optimal, herein, means that numerical model results are reasonably representative of the experimental data with the fewest effective particle size classes used, thereby maximizing computational efficiency. Although modeling with more size classes can be equally accurate, results from this study indicate that using three effective particle size classes to estimate the distribution of sediment sizes is optimum. [ABSTRACT FROM AUTHOR]