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AlMashan, N.; Al-Attar, I., and Neelamani, S., 2024. Assessment of annual sedimentation into Failaka Marina (Kuwait) and possible solutions for reduction of siltation. Journal of Coastal Research, 40(3), 527–553. Charlotte (North Carolina), ISSN 0749-0208. Sedimentation is critical for ports, harbors, and marinas, requiring accurate assessment. Failaka Marina in Kuwait is experiencing a severe noncohesive sedimentation problem. The samples collected at the seven locations along the beach showed that the beach has a uniform grain-size diameter, meaning it is poorly graded sand. The sampling at the tip of the southern breakwater showed that the shoaling is mainly sand. The suspended-sediment concentration varies from 0.025 kg m–3 to 1.2 kg m–3, whereas the mean concentration at the marina entrance is 0.85 kg m–3. The time series of the suspended solids over a year in the seawater surrounding Failaka Island shows a range of 8 to 48,069 ppm. Such a considerable variation in suspended load is due to the massive amounts of dredging and spoil disposal at Boubyan Island and Basra Port (Iraq) when a high sediment load moves around Failaka Island with a concentration of more than 40,000 mg L–1. Annual sedimentation is about 2.35 m y–1, which is responsible for blocking the main entrance for navigation. Kuwait's Ministry of Communication allocates $4 to $6 million annually for dredging and disposal activities. This study evaluates the six marina entrance modification scenarios to determine the best scenario that achieves a measurable reduction in sedimentation rate in the Marina. Six marina breakwater modifications were studied, and annual sedimentation rates were numerically computed. The study use Coupled MIKE 21/3 to simulate hydrodynamic conditions for cohesive sediment transport in a problem area. Field data from 2015 calibrated and validated the model. The primary sediment-moving force is SE wind and sea-swell waves. Littoral drift along Failaka Island's southern coastline and high suspended-sediment concentration result in littoral drift and settling. The best scenario showed a 28% sedimentation reduction and a 26% reduction in maintenance dredging costs from the six studied scenarios. [ABSTRACT FROM AUTHOR]

Woo, H.J.; Lee, J,-H.; Choi, J.U., and Kang, J., 2020. Changes in sedimentary processes in macrotidal flats in Garolim Bay, West Coast of Korea. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 722-726. Coconut Creek (Florida), ISSN 0749-0208. Garolim Bay, on the central western coast of Korea, is a semi-enclosed macro-tidal bay with extensive tidal flats that occupy approximately 77% of the bay surface area. The study investigated the sediment characteristics and sedimentation rates to elucidate the spatial and temporal variations in the sedimentary processes in the bay. Surface sediments were sampled to grain-size distributions at 158 stations in July 2002 and July 2014 in the spring tidal cycle. Grain-size distributions were analyzed using standard sieving for the sand fraction and a particle size analyzer for the mud fraction. The geomorphic changes associated with sediment deposition or erosion were investigated along six transect lines on the tidal flats from February 2014 to February 2015 in the ebb tide. The area of sand and muddy sand sediments had extended from the outer to the middle bay in summer 2014, and the percentages of mud were higher in the inner bay compared to the surface sediment distributions in summer 2002. The short-term sedimentation rates from February 2014 to February 2015 showed that erosion was dominant on the tidal flats in the inner bay during spring and on those in the outer bay during winter, with net erosion rates of –1.55 and –55.23 mm/year, respectively. In the middle bay, deposition dominated on the tidal flats, with net deposition rates from 4.85 to 18.94 mm/year. The sediment transport vectors calculated using grain-size parameters for 2002 and 2014 showed that in 2002, sandy sediments were predominantly transported along tidal channels at the bay entrance. However, in winter, sediments from the tidal flats in the outer and middle bay areas are transported to the inner bay by wind-driven waves and tidal currents, resulting in the deposition of sediment on the tidal flats in the inner bay. In summary, the results show that the sediment transport patterns in Garolim Bay changed between 2002 and 2015 due to increased suspended sediment supply and erosion of the tidal flats in the outer bay. Based on these knowledge of sedimentary processes, the major control factors for seasonal variations in sedimentation on the tidal flats in Garolim Bay are tidal currents, wind-driven waves, and sediment inputs. [ABSTRACT FROM AUTHOR]

Muin, M. and Muslim, A.B., 2023. Anak Krakatau Landslide Tsunami and sediment transport simulation using non-orthogonal boundary fitted technique in spherical coordinate model. 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. 146-150. Charlotte (North Carolina), ISSN 0749-0208. This paper presents a simulation of a tsunami induced by the Anak Krakatau Landslide in Indonesia and the sediment dispersion transported by the tsunami. The hydrodynamic model of this simulation used a non-orthogonal curvilinear technique in Spherical Coordinates and was developed in GIS on Windows System, named MuTsunami. The advantages of MuTsunami are rapid computation, accurately solving complex geometry, and integrating with the sediment transport model. This software is suitable for an early warning system. MuTsunami has also been applied in the 2010 Mentawai and 2004 Aceh Tsunami. The results show good agreement with the observation data. The simulation results indicate that the tsunami reached Serang, Ciwandan, Kota-Angung, and Panjang within 1860, 2760, 2100, and 4140 seconds after the Anak Krakatau Landslide occurred. The waves along the coast occurred up to 9 m and 8 m for Banten and Lampung coasts. The sediment transport result shows bathymetric changes along the Banten coast 30 minutes after the landslide. The required time to simulate the tsunami from the Anak Krakatau Landslide is only 15 seconds which is suitable for an early warning system. [ABSTRACT FROM AUTHOR]

Li, H.; Beck, T.M.; Moritz, H.R.; Groth, K.; Puckette, T.; Marsh, J., and Sánchez, A., 2019. Sediment tracer tracking and numerical modeling at Coos Bay inlet, Oregon. Journal of Coastal Research, 35(1), 4–25. Coconut Creek (Florida), ISSN 0749-0208. An investigation was conducted on transport of dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to the Coos Bay inlet, Oregon. A sediment tracer release/sampling and field data collection program was carried out and a numerical hydrodynamic, wave, and sediment transport model, the Coastal Modeling System, was developed to perform the analysis of sediment transport around the inlet system and the ODMDS. The data were used to calibrate and validate model calculations, and the model was set up to calculate sediment fluxes and to simulate the process of sediment tracer release and movement, and determine the pathways of sediment tracer under combined wave, current, and wind conditions within and around the immediate vicinity of the Coos Bay ODMDS. The calculations and the measurements indicate that sediment tracer movement is primarily controlled by tidal current inside Coos Bay and at the inlet entrance, and responding to wave and storm conditions in the open coastal area. A divergence in net sediment transport directions in the adjacent nearshore beach was apparent in the results of the tracer release and numerical simulations. This methodology may be used to determine sediment bypassing pathways and optimal placement of sediment within a nearshore environment adjacent to tidal inlets. [ABSTRACT FROM AUTHOR]

Appeaning Addo, K., 2018. Assessing ocean wave dynamics, potential sediment transport, and coastal erosion along Accra coast in Ghana. 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. 76–85. Coconut Creek (Florida), ISSN 0749-0208. This study assessed wave dynamics and sediment transport along the coast of Accra in Ghana and compared the results with coastal erosion trend. Wave data from NOAA global wave model and measured buoy wave data were analysed as well as the potential sediment transport using the CERC's equation. The estimated mean significant wave height was 1.40 m and the period was between 10 and 15 seconds. The potential sediment transport rate was between 4.1 ×105 m3/yr and 4.1 ×105 m3/yr, while coastal erosion rate was 1.13 m/yr. Potential sediment transport rate increases from west to east. Coastal erosion is relatively high along the eastern and western coasts of Accra, while the central coast is relatively stable. Wave heights increased gradually from 1.00 m in January to a peak of 1.73 m in August, and eventually decreased to 1.10 m in December. The shape of the nearshore profile is significantly different along the eastern coast relative to the western and central coasts. This indicates that sediment transport intensity and nearshore bathymetry interaction in part explain the rate of erosion observed along the Accra coast in Ghana. [ABSTRACT FROM AUTHOR]

ABSTRACT Fernández-Fernández, S.; Silva, P.A.; Ferreira, C.; Ribeiro, A.S.; Abreu, T.; Romão, S.; Baptista, P.; Fontán-Bouzas, A.; Dias, J.M..; Coelho, C., and Bernardes, C. 2018. Assessment of Dredging/Dumping Scenarios for Figueira da Foz Coastal Region (W Portugal). 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. 1266–1270. Coconut Creek (Florida), ISSN 0749-0208. Figueira da Foz coastal region (W Portugal), that comprises sandy beaches and the Mondego estuary-inlet, is exposed to the high energetic wave climate of the North Atlantic Ocean, which induces important local morphological changes. These changes entail shoaling problems as the formation of a submerse sandbar at the inlet which can block navigation towards local harbor. Therefore, coastal dredging is a non-structural temporal solution for this problem. Nevertheless, dredging activities have an impact on local hydrodynamic processes that should be known beforehand. The aim of this study is to clarify this issue using modeling tools dedicated to help stakeholders in decision making process. For that purpose, Delft3D-WAVE module propagates the most representative regional wave conditions under four dredging scenarios including the respective dump areas. Additionally, Delft3D-FLOW module simulates tidal flows along spring and neap tides. The hydrodynamic parameters, significant wave height, orbital velocity, wave-induced currents, tidal current velocity and total sediment transport are analyzed in comparison with numerical solutions obtained in reference scenario (no dredging and no dumping). The results highlight changes in these hydrodynamic parameters in dredging and dumping areas as well as in surrounded areas. Different scenarios draw a similar change pattern for different parameters, namely a reduction of flow velocity intensity within dredged areas and their increase in adjacent areas. Furthermore, hydrodynamic alterations intensify in response to the increase in significant wave height and wave direction considered. These findings are the basis for understanding the influence of dredging and dumping operations on the hydrodynamic of this coast. [ABSTRACT FROM AUTHOR]

Son, S.; Kim, J.; Yoon, H.-D.; Jung, T.-H.; Do, K., and Shin, S., 2017. An observational and numerical study of storm-induced morphologic changes at Sanpo Beach, Korea. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 334-338. Coconut Creek (Florida), ISSN 0749-0208. This study was conducted to investigate morphological changes at Sanpo Beach due to the storm through field observation and numerical simulation. Sanpo Beach located on the southeast coast of Korea had been significantly affected by typhoon Goni while some changes in beach profile was expected due to the strong storm-induced currents. Series of field observations on the beach topography, bottom bathymetries, shorelines, sand samples, and incident waves were carried out in order to investigate the morphological changes at Sanpo Beach during the typhoon season. In particular, Real Time Kinematic-Global Positioning System (RTK-GPS) and single-beam echo-sounder were deployed to collect beach topography and bottom bathymetry data, respectively. Observational results represented spatial and temporal changes of shoreline and sand bars during a storm event. For more close look at the process of morphologic changes derived by the sediment transport mechanism, field-scale numerical simulations were performed in parallel using Xbeach. Xbeach is one of the widely-used, open-source models which calculate sediment transports and morphologic changes by hydrodynamic processes of short (and/or long) waves, wave-induced setup and unsteady currents. Bathymetric evolutions, as well as shoreline changes predicted by the numerical results, revealed good agreements with observational data. [ABSTRACT FROM AUTHOR]

Kim, H.-J.; Suh, S.-W.; Seok, J.-S., and Park, W.-K., 2017. Sedimentation for a flood-dominant estuarine harbor induced by anthropogenic activities. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 339-343. Coconut Creek (Florida), ISSN 0749-0208. Sedimentation around the Kunjang harbor area in Korea has intensified at a rate of ~2.0 m/yr because of the construction of an estuarine dam in 1988, which resulted in the tidal energy being blocked and the development of a flood-dominant environment. The construction of several harbor facilities cumulatively altered the tidal hydrodynamics and yielded sedimentation. Moreover, the annual maintenance dredging for the main channel accelerated alteration. In order to understand the sedimentation characteristics, archived intensive depth measurements were used to assess the variations in the bottom shear stress. Our results showed that the bottom shear stress and tidal prism have lessened. The resulting sedimentation should be managed through dredging or minimization plans based on an appropriate engineering solution. In this paper, we suggest an optimized weighting factor to represent diverse physical morphological variations that affect the shear stress. It can be used to compensate for unsatisfactory results generated by a morphological model. Our findings can help in devising an efficient engineering approach to mitigate sedimentation for a flood-dominant estuarine harbor. [ABSTRACT FROM AUTHOR]

Kong, J.; Pan, M.; Shen, C.; Hua, G., and Zhao, H., 2016. Analysis of the morphological changes and related sediment transport mechanisms of the Baisha Shoal in the Qiongzhou Strait, China. The morphological changes and evolutionary mechanism of the Baisha Shoal in the Qiongzhou Strait were investigated using various methods, including bathymetric chart comparisons, geomodeling, hydrodynamic modeling, and hydrologic statistical analysis. Water depths were extracted from digitized charts to explore the evolution of the Baisha Shoal and to quantitatively estimate the changes in the shoal area within the 5-m isobath. The grain-size trend analysis (GSTA) model was introduced to explain the features of bed sediment distribution and to analyze the sources of the sediment. Tidal flow models and wave models were adopted to simulate the tidal flows and wave fields around the Baisha Shoal and to reveal the sediment transport dynamics. Further comparisons based on a Mann-Kendall trend analysis and remote-sensing image data from different years were used to discuss the reason for the recent evolution of the Baisha Shoal. The results show that the formation of the Baisha Shoal was caused by the combined effects of reciprocating flow in the eastern and western directions and waves from the NE direction. However, in recent years, the Baisha Shoal has demonstrated an unsteady geomorphological state and is transitioning from a deposition-dominated state to an erosion-dominated state. Erosion has become most significant since 2004, as reflected in the shoal area within the 5-m isobath, which is decreasing by 0.732 km2/y. The analysis demonstrated that a reduction in sediment load and increased sand mining are the two most significant factors that are progressively altering the shoal morphology. If these issues cannot be resolved, the strong dynamic surroundings will aggravate the erosion of the Baisha Shoal. This study on the Baisha Shoal highlights the necessity of combining different approaches to better understand coastal evolutionary features, dynamic mechanisms, and evolutionary causes, as well as to guide future coastal protection engineering design. [ABSTRACT FROM AUTHOR]

Wang, J.; Liang, B.C.; Li, H.J.; Pan, X.Y.; Lee, D.Y., and Xu, Y., 2016. Swash motion driven by the bore and prediction of foreshore profile change. 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. 492-497. Coconut Creek (Florida), ISSN 0749-0208. The prediction of a swash zone bed profile resulting from complex hydrodynamic processes is a challenging task. A series of laboratory experiments at a 2D wave flume were carried out to investigate the evolution of foreshore profiles and sediment transport in the swash zone. The swash motions and the changes of foreshore profiles at the different stages of foreshore evolution were measured for 12 cases of different combinations of wave height, wave period and water level for two different initial beach slopes (1/5 and 1/15). From the evolution of foreshore profiles detected by side looking video cameras mounted to the glass wall of a 2D wave flume, the sediment transport rates were estimated precisely both in time and space using the 1-D sediment conservation equation. The characteristics of the instantaneous sediment flux of swash motion and feasibility of its prediction were discussed. The characteristics of the swash-averaged net sediment flux at different stages of beach evolution were investigated by detecting the detailed net flux at 2 minute intervals from the precise beach profile changes. Simple methods of prediction of sediment transport and foreshore profile change are discussed for swash motion driven by bores. [ABSTRACT FROM AUTHOR]

Pan, S. and Fairbairn, G., 2016. Impacts of Submerged Breakwaters on Nearshore Sediment Transport. 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. 1212 - 1216. Coconut Creek (Florida), ISSN 0749-0208. Submerged breakwaters have been increasingly popular as the coastal defence structures due to the advantages of the low construction costs and less visual intrusion. However, the impacts of the structures on nearshore sediment transport and beach morphology remain unclear. This paper presents the results of beach morphological changes affected by different submergence of a group of shore-parallel breakwaters under the combined wave and tide conditions from a depth-average process-based coastal morphological model - COAST2D. In this study, different breakwater crest levels are used in the model under both storm waves and tides based on the field measurements at the Elmer breakwater scheme site to investigate the impacts of the breakwater submergence on nearshore hydrodynamics and morphological changes. The results show that the fully submerged breakwaters produce more stable and balanced sediment loss/gain in the protected area, and yield more desirable formation of salients behind the breakwaters. The results also reveal the complex nearshore processes and morphological changes under the extreme waves for further study. [ABSTRACT FROM AUTHOR]

Detailed video images and ADCP measurements were used to describe the processes of suspended sediment transport by the Mataquito River into the Pacific Ocean. It is found that, in the absence of fluvial flood discharges, suspended sediment transport to the sea only takes place during low tide periods and it is characterized by pulses of different frequencies that in turn are related to the spatial velocity distribution at the river inlet. It was observed that at low tide the highest velocities are near the mouth of the river, presenting an heterogeneous spatial distribution. In this high speed zone, we hypothesized the shear stresses are big enough to re-suspend fine sediment that is transported into the ocean by the main river current. A simple conceptual explanation based on these findings is presented, seeking to explain the observed dynamic equilibrium of the Mataquito River inlet after the significant alterations produced by the 2010 M8.8 earthquake and tsunami. [ABSTRACT FROM AUTHOR]

Our current understanding of the morphodynamics in swash and surf zones is limited due to their turbulent and irregular nature. The importance of this zone to sediment transport led us to perform a sophisticated field experiment using painted sediments. Sediments collected locally from beach ridges were sorted into the following diameters: 1-2.5 cm, 2.5-5 cm and 5-10 cm. The sediments were painted, amassed in piles and placed at 0.5-10 m depths in three sites near the Estonian coast. The locations were recorded with GPS devices and photographed. The sediment piles placed in the sea were monitored at least once after an intense storm or once before and after the storm season. Some sediments were placed on the shoreline and monitored daily for a shorter period. Hydrodynamic parameters were also measured or hindcasted during the experiment. We found that wave breaking during storms can take place even at 6 m depth, but mostly between 2-4 m depth. Sediment fractions between 1-10 cm diameters can be transported over 20 m towards the shore. Even sediment piles at 10 m depth were moved 2-4 m, but towards the open sea. Sediments accumulated on the shoreline moved up to 3 m/hour along the shore and approximately 350 m during three months. We also found that calm periods can be more influential in places where regular vessel-generated waves wash the shores. As vesselgenerated waves often approach from a different angle than natural waves, they can cause notable erosion during the periods when natural waves are weak or absent. [ABSTRACT FROM AUTHOR]

Brill, D.; Pint, A.; Jankaew, K.; Frenzel, P.; Schwarzer, K.; Vött, A., and Brückner, H., 2014. Sediment transport and hydrodynamic parameters of tsunami waves recorded in onshore geoarchives. In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial environments, and (2) the onshore flow velocities and flow depths of associated tsunami waves were estimated by means of sedimentation modelling. In the case of the Indian Ocean tsunami (IOT) of 2004, modelled flow velocities of 3.7 to 4.9 m/s, modelled onshore flow depths of up to 5.5 m, and a sediment source from offshore areas shallower than a 45-m water depth-including littoral sediments transported as bedload and suspended load from the shallow subtidal zone-are in agreement with quotations based on survivor videos and posttsunami surveys. For a 500- to 700-year-old predecessor, comparable flow velocities and flow depths of 4.1 to 5.9 m/s and 4.0 to 7.5 m, respectively, were modelled, indicating a similar magnitude as the IOT 2004. Comparable values of maximum transport distance and depth of wave erosion were also found. In the case of three older tsunami candidates, dated to 1180 to 2000 cal BP, the deposits indicate partly similar source areas with water depths of less than 45 m and partly shallower source areas restricted solely to the beach. Whereas the former tsunamis are interpreted as events similar to 2004, the latter are more likely storms or tsunamis of a lower magnitude. [ABSTRACT FROM AUTHOR]

Cohn, N., Ruggiero, P., Ortiz, J., D.J. Walstra, 2014. Investigating the role of complex sandbar morphology on nearshore hydrodynamics. 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. 053-058, ISSN 0749-0208. Coastal environments are characterized by complex feedbacks between flow, sediment transport, and morphology, often resulting in the formation of nearshore sandbars. In many locations, such as Hasaki (Japan), the Netherlands, and the Columbia River Littoral Cell (CRLC, USA), these sandbars exhibit a net offshore migration (NOM) cycle whereby these features form in the inner surf zone, migrate seaward and decay offshore on interannual cycles. Depending on the stage of the cycle, the number and configuration of the bars may differ widely. It has long been recognized that sandbars act as natural barriers during storm events by dissipating wave energy through breaking far from the beach face. Thus, dependent on the stage of the NOM cycle, one might expect significant variability in nearshore hydrodynamics. Using a non-linear wave model we demonstrate that inter-annual variability in sandbar configuration can significantly alter inner surf zone and swash zone processes. The model indicates that under different end-member NOM stages the same wave conditions can result in up to a 36% variance in the vertical extent of infragravity runup and can alter both the rate and direction of net cross shore sediment transport. [ABSTRACT FROM AUTHOR]

The efficiency of a rocky headland in delimiting littoral cells and preventing sediment bypass was investigated in a coastal area of Liguria (Italy, NW Mediterranean). This area harbours two contiguous pocket beaches separated by a headland that can be considered as a geomorphic and hydrodynamic limit of two littoral cells. Surveys using a single- beam echo sounder were carried out in order to update historical data on the morphology and hydrodynamics of the area. Sediment samples were collected from the foreshore and the nearshore in two pocket beaches, and sediment (including gravel) transport patterns around the headland were described. Distribution and state of health of the endemic seagrass Posidonia oceanica were assessed in order to explore potential links among sediment transport, hydrodynamics, and meadow development. A rip current transporting sediments with an updrift origin to the downdrift beach was evidenced, causing gravel sediment bypass between the two contiguous littoral cells. The direction followed by the rip current was largely influenced by the P. oceanica meadow, which hindered its flow towards the open sea. The shape of sediments and their grain size have been shown to play a significant role in the sediment transport patterns around the rocky headland. [ABSTRACT FROM AUTHOR]

The present work investigates the decadal morphological evolution of a microtidal, perched beach and the effect that beach rock formations can have on coastal morphology. Using historical and recent morphological observations from Ammoudara Beach on the island of Crete, Greece, and numerical modeling, the interaction of beach rock formation and retreating coastline are investigated. The principal feature of the morphological evolution of the coastal zone under investigation has been the transformation of a beach rock formation, initially attached to the shoreface (1950s), to a submerged reef that is aligned subparallel to the present-day shoreline. At present, the beach rock is attached to the shoreface at sea level at the western part of the beach, but it has evolved to a submerged reef toward the east, being approximately 40 m off the shoreline at the central part and ~70 m off the coastline at the eastern part of the beach. This kind of beach evolution is attributed to the interplay of natural hydrodynamic and sediment transport processes (that have been changing as the beach rock formation evolved to an offshore submerged reef) and to human intervention. The latter is exhibited mainly as changes in the sediment supply to the coastal zone (e.g., reduction in terrestrial freshwater/ sediment influx, deterioration of sand dune field, and arbitrary abstraction of beach material). After a period of readjustment of the nearshore hydrodynamics to the changing morphology and vice versa, it seems that, at present, Ammoudara Beach has attained a new morphodynamic equilibrium where the shore-parallel reef acts as a submerged breakwater. [ABSTRACT FROM AUTHOR]

Mafi, S., Yeganeh-Bakhtiary, A., Kazeminezhad, M.H., 2013. Prediction formula for longshore sediment transport rate with M5' algorithm One of the most vital tasks for coastal engineers is to calculate the gross longshore sediment transport rate (LSTR) to control the shoreline erosion and beach evolution. In the past decades, several empirical formulas or parametric models have been proposed for predicting the gross LSTR as a function of the breaking wave characteristics, bed materials and beach slope. The main downside with these formulas is that they give wide range of different rate of predictions; consequently their reliability under the changing hydrodynamic conditions is very uncertain. In the present study, an alternative approach based on the Regression Trees (M5') was applied to present a new formula for prediction of LSTR in terms of the longshore sediment transport coefficient ( ℇ). Several high-quality data sets were employed, which comprise of the wave parameters, sediment characteristics and the longshore transport rate. Based on the obtained results, the Shields parameter was selected as the main input variable, while the longshore sediment transport coefficient ( ℇ) was given as the output parameter. The M5' algorithm was employed for building and evaluating the regression trees, which showed that regression trees can be used successfully for the prediction of LSTR. Finally, the performance of the new M5'-based formula in the prediction of LSTR was compared with the previous formulas. The results indicated that the error statistics of the regression trees were less and it is evidently predicts the LSTR more accurate than the previous mentioned formulas. [ABSTRACT FROM AUTHOR]

Pedrozo-Acuña, A., Resendiz, D., Gutiérrez, C., 2013. Experimental study on sediment advection and beach response under plunging wave breaking. This paper presents an experimental investigation into the morphological response of beaches under the action of plunging wave breaking. Experimental results performed under the same wave conditions, allowed the association of beach evolution to its porosity. Firstly a beach profile which presented the generation of a clear berm at the top of the profile and a beach step below the SWL (higher porosity) was illustrated. Secondly, an erosive condition of beach profile was characterised (lower porosity). The morphological responses of both beaches were differentiated in terms of the porosity of the beach, which highlight its role in the resulting spatio-temporal nature of the momentum balance under plunging wave breaking. Additionally, BIV derived velocities were utilised as a tool for the investigation of hydraulic regimes responsible of generating different beach responses and sediment sorting in the laboratory. Through Euler's equation the total acceleration was deconstructed, allowing a careful assessment of the contribution of each the acceleration terms to the resulting momentum balance. Notably, the contribution of the local acceleration term is insignificant all along the beach profile, while the role of advective terms cannot be overlooked. [ABSTRACT FROM AUTHOR]

Valentim, J.M., Vaz, L., Vaz, N., Silva, H., Duarte, B., Caçador, I. and Dias, J.M., 2013. Sea level rise impact in residual circulation in Tagus estuary and Ria de Aveiro lagoon. Nowadays, there is a special concern about the possible impact of sea level rise in hydrodynamic patterns of coastal systems and its consequence in contingent ecosystems. In the present work, the effects of sea level rise in residual circulation are analyzed in two of the most important Portuguese coastal systems, Ria de Aveiro lagoon and Tagus estuary. The role of rivers inflow on residual circulation is also analyzed under different sea level scenarios. Several projections of river discharges were considered and two scenarios for sea level were adopted: actual and locally predicted sea level rise. The methodology followed comprises the exploitation of previously validated 2D hydrodynamic numerical models (MOHID) developed for both systems. Results indicate that rivers discharge effect cannot be unconsidered in the long term hydrodynamic analysis for both systems, once residual currents intensity could be at least 40% and even 100% higher in maximum inflow than in typical inflow and no discharges scenarios, respectively. In Tagus estuary, the upper bay is the most affected area in a sea level rise scenario, namely in the upper zone (with extensive intertidal areas) where differences in the residual currents intensity can be higher than 100%. In Ria de Aveiro lagoon, differences between actual and sea level rise could be higher than 80%. Narrow and shallow channels are the most affected areas, revealing the significant impact of sea level rise in the intertidal zones. Consequently, the predicted changes in these systems hydrodynamics could influence the long term transport and their actual equilibrium and, as such, affect the natural state of the contingent biological communities. [ABSTRACT FROM AUTHOR]

Schindler, R.J., Bass, S.J. and Manning, A.J. Effects of non-cohesive particles on suspended particle characteristics in a partially flocculated estuary during spring tides. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) We present unique, in-situ data describing suspended particle populations in a meso-tidal estuary over the tidal cycle where the proportion of cohesive and non-cohesive sediment varies temporally. Simultaneous measurements of sediment concentration and hydrodynamics reveal that suspended particle characteristics are highly variable over the tidal cycle primarily due to the variable presence of non-cohesive sands, rather than changes in suspended particulate matter concentration (SPMC) and turbulent shear stress (τ). The particle distributions reveal that sand fractions appear in suspension throughout the tidal cycle as part of flocs and as individual grains. Non-cohesive or dense, consolidated mud fractions are sourced primarily from bedload under high τ, particularly during flood acceleration. However, the flood-deceleration phase experiences an influx of advected marine sands that increase suspended sand content despite declining velocity and turbulent shear stress. This generates bimodality in particle distributions and mean particle characteristics are misleading. Comparison with data collected at the turbidity maximum zone, beyond the extent of non-cohesive particles, shows that population size, settling velocity and density vary significantly between locations despite being <10 km apart. The implications of this spatial variation for our understanding of estuarine sediment transport are discussed. [ABSTRACT FROM AUTHOR]

Frias, P., Horta, J., Almeida, L.P., Pacheco, A., Ferreira, Ó., 2013. Development of a WebGIS tool to determine tidal inlet evolution. In: Conley,D.C., Masselink, G., Russel, P.E.and O'Hare, T. J. (eds.) Research into the consequences of engineering works on the long-term behaviour of inlet systems has been hindered by the absence of suitable datasets, the shortcomings of existing formulae and evaluation tools. Cross-sectional channel areas adjust to hydrodynamics and sediment transport conditions. The impacts of a new inlet on the adjacent shoreline can be unpredictable and are difficult to quantify. This paper presents the development of a Web GIS tool (WebInletAnalyst) that allows any coastal or hydraulic engineer to autonomous extract the evolution of key tidal inlet parameters such as minimum cross-section area, inlet width, maximum depth and migration distance, from a set of bathymetric charts and raw data surveys. The tool is built on a web interface written and compiled using source codes. The tool was applied to a test case (Ancão Inlet, Ria Formosa, Portugal) using available datasets and compared with results from other studies, following the Coastal Engineering Manual guidelines. Overall results showed that mean differences between manual and automate techniques were small and randomly distributed. The user' definition of the location and orientation of minimum cross-section profile affects the accuracy of the tool. Further improvements on the available web interface tool are being tested to allow a magnified view of the inlet channel area and a better precision on sketching the minimum cross-section profile. The tool will be ultimately made available on Python code, allowing future further improvements and adaptations by the scientific community. [ABSTRACT FROM AUTHOR]

Ernstsen, V.B., Lefebvre, A., Kroon, A. and Niemann, S.L., 2013. Oblique second-order sand transport patterns on an intertidal sand flat in a natural tidal inlet system. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) A detailed digital elevation model (DEM) of an intertidal sand flat in the Knudedyb tidal inlet in the Danish Wadden Sea, derived from high-resolution Light Detection And Ranging (LiDAR) data, reveals a large elongated bedform field with complex bedform morphologies and drainage channel networks. This indicates distinct second-order sand transport pathways oblique to the main tidal transport pathways. A conceptual model for the development of the bedforms and channels is presented, which comprises hypotheses of the hydrodynamic forcing of the different second-order sand transport pathways. During flood tide, sand is transported along ESE-oriented pathways across the intertidal flat towards the inner tidal basin. During the late stages of ebb tide, sand is transported in drainage channels (WSWoriented) from the intertidal flat towards the inlet channel. During storm events with winds from SW, wave-generated currents transport sand along a NE-oriented transport pathway from the inlet channel towards the intertidal flat. [ABSTRACT FROM AUTHOR]

White, J.L., 2013. Measuring clast transport signatures at a barrier terminus. At a macrotidal prograding and transgressive, mixed sand and gravel barrier, continuous gravel transport logging provides insights into the relationships between the incident hydrodynamics and the morphodynamics. Two piezoelectric gravel transport sensors (GTS) were aligned in either the cross-shore or the alongshore directions over two low and two moderate energy equinox spring tide events. GTS measure gravel transport as an electronic pulse, where the frequency and amplitude measures clast transport rate and presumably number coincident with the passage of a wave, or per event. Clast transport occurs in bursts characterised by greater than average amplitude peaks, thought to coincide with wave phenomena. Further, these bursts do not appear to progress in a linear relationship with the wave parameters. For example, series of burst can be greater before, or after high tide, and are often polymodal, and low wave energy transport rates can be greater than moderate transport rates. The cross-shore configuration measured the clast transport over a gravel substrate at a high water ridge, and the adjacent landward high tide swash zone. As expected transport frequencies were greater over the high water ridge than at the adjacent swash zone. However, the clast transport per wave can be greater at the swash than at the high water ridge, suggesting the importance of the prolonged breaking wave inducing clast transport. The average number of clasts transporting per event can be greater at the high water ridge than at the swash. Also, sediment volume changes were greater on the high water ridge, marked by small depositions, where as the swash zone could be depositional, or erosional. The longshore configuration measured the simultaneous clast transport over gravel or sand substrates. The transport frequencies were greater over the gravel than the sand substrate. Greater volumes of sediment were transported to landward over the sand than the gravel substrates. The clasts transporting over the sand substrate per wave can be greater than clasts transporting over the gravel substrate, suggesting the importance of sand transport and accumulation as a process associated with prograding gravel barriers. However, the average number of clasts transporting per event over the gravel were generally greater than over the sand substrates, hence gravel substrate clasts can transport but with little net transport direction. The deployment of GTS enables indications of gravel transport characteristics continuously within an active barrier system environment. [ABSTRACT FROM AUTHOR]

Thorpe, A., Miles, J., Masselink, G., Russell, P., Scott, T., Austin, M., 2013. Sediment Transport In Rip Currents on a Macrotidal Beach Rip currents are offshore-directed flows in the surf zone that may be responsible for significant offshore transport of sediment. In this study high frequency surface elevation and current velocity data were collected alongside suspended sediment concentrations in a rip channel on a high energy, macro-tidal beach. At low tide (water depth over the rip channel ( h) = 0.9 m), when the rip current was active (maximum offshore directed flow = ~ 0.4 m/s), net suspended sediment transport was directed offshore, and 88% of the flux was due to the mean flow component. The rip current was found to pulse at very low frequencies (VLF) and this contributed significantly to offshore sediment transport, accounting for 48% of total oscillatory flux (not considering direction). Infra-gravity (IG) frequency oscillations had a marginal contribution to offshore sediment transport within the rip (10% of total oscillatory flux) and incident wave transport was onshore (42% of total oscillatory flux). The relative influence of the wave component increased as tidal elevations increased and the rip current became inactive. For comparison, at mid-tide ( h = 3.5 m) the total suspended sediment flux was in the offshore direction and four times less than during low tide. The mean flux accounted for 34% of the total transport at mid-tide. At high tide ( h = 6.1 m) the total sediment transport was in the onshore direction due to the incident waves, with a 0% contribution from the mean flux. [ABSTRACT FROM AUTHOR]

Tõnisson, H., Suursaar, Ü., Rivis, R., Kont, A. and Orviku, K., 2013. Observation and analysis of coastal changes in the West Estonian Archipelago caused by storm Ulli (Emil) in January 2012. The study analyzes the meteorological parameters, hydrodynamic conditions and coastal changes at three practically tideless locations on Saaremaa Island caused by storm Ulli (sustained wind speed 20 m/s, gusts 28 m/s) which struck the Estonian coast on 4 January 2012. It was the last and the most influential storm of a series of storms which began on November 2011. Wind and sea-level data from nearby meteorological and hydrological stations were used to provide the forcing data for hydrodynamic study. Wave hindcast was performed using a semi-empirical SMB-type wave model. Shorelines, scarp positions and beach profiles were measured in August 2011, and again during each of storm Berit (in November) and storm Ulli (in January). Local storm surge height reached 1 m, significant wave height (Hs) was up to 2.8 m, the combined sea level and Hs reached 3.65 m, and local wave run-up reached 3.2 m during Ulli. At Cape Kiipsaare, recession of the sandy scarp reached 9 m (at the rate of nearly 1m per hour). The loss of sand was approximately 4-5 m3 per 1 m of shoreline. Erosion occurred on the shores exposed to the prevailing wind direction while accumulation was recorded on the leeward side of the spit. Erosion mostly occurred at the elevations between 1-3 m. Although the winter 2011/12 included a series of influential storms, nearly two-thirds of coastal erosion during the winter 2011/2012 was caused by storm Ulli, which featured the highest sea levels. [ABSTRACT FROM AUTHOR]

Vila-Concejo, A. Harris, D.L., Shannon, A.M., Webster, J.M., and, Power, H.E., 2013. Coral reef sediment dynamics: evidence of sand-apron evolution on a daily and decadal scale This paper investigates sand apron progradation on decadal and daily scales on a platform reef (One Tree Reef, OTR) located in the southern Great Barrier Reef. The decadal scale is addressed by analysing sand apron progradation using remotely sensed images (aerial photos and satellite imagery) coupled with wind data and cyclone events. The daily scale is addressed through a field campaign that was undertaken in September-October 2011. The campaign consisted of hydrodynamic measurements in three stations over the southern sand apron in OTR. It was found that while there was a small overall progradation over the last 31 years, the progradation had not occurred continuously or consistently along the entire sand apron. Additionally, the effect of cyclones was not clear on the decadal scale. On the daily scale, it was found that currents are generally weak (<0.4 m/s) and that currents during conditions at which suspended sediment is maximized are ocean-ward directed on the central part of the sand apron and lagoon-ward directed on the easternmost end. As such, daily sediment transport does not represent a gross contribution to lagoon infilling by sand apron progradation. Our results show that sand apron progradation does not occur continuously on the decadal or the daily scale. [ABSTRACT FROM AUTHOR]

The hydrodynamic and morphodynamic parameters of a region in southern Brazil were determined by collecting sediments with stream traps (bedload and suspended load) in the surfzone and capturing images, studying topography, and researching sedimentology with the help of a movie camera, a total station, and laboratory work. Data on deep-water waves were garnered with a CPTEC/INPE model. Field work was carried out in 50 field trips during a 1-year period; 42 out of 50 trips focused exclusively on hydrodynamic and morphodynamic data, whereas eight of the trips were also used for collecting sediments. In addition, data on wind direction and velocity and on the longshore currents were also collected. All data were obtained in normal atmospheric conditions. Field work was carried out in six cross-shore profiles along Cassino Beach and Mar Grosso Beach (three profiles on each side of the estuary of Patos Lagoon). [ABSTRACT FROM AUTHOR]

The Eastern Scheldt tidal basin in the SW part of the Netherlands has seen dramatic changes due to human intervention in the past few decades. The construction of two back-barrier dams in 1965 and 1969 had a significant impact on tidal hydrodynamics and sediment transport. The effects of these interventions were still ongoing when the hydrodynamic regime was altered again by the construction of the storm surge barrier between 1983 and 1986. This research describes the hydrodynamic and morphological evolution of the Eastern Scheldt ebb-tidal delta between 1960 and 1983, before construction of the storm surge barrier started. The analysis focuses on how the back-barrier dams changed the tidal flow on the ebb-tidal delta and how these altered hydrodynamics influenced sediment transport and morphology. It starts with a description ofthe observed hydrodynamic and bathymétrie changes. These observations are used as input for a process-based numerical model (Delft3D FLOW), which is used to simulate situations before and after channel closures. In the decades before 1965, the Eastern Scheldt exported large quantities of sediment towards the sea through its inlet. The implementation of the dams caused a significant increase in tidal prism, which was observable in the response of the bathymetry; the export and the rates of channel deepening and ebb-tidal delta growth both increased. Analysis of tidal-flow measurements and model output show a persistent trend for sediment transport towards and out of the Eastern Scheldt inlet. The construction of the back-barrier dams only amplified this export by increasing the tidal prism and pushing the basin out of equilibrium even more than it apparently already was. [ABSTRACT FROM AUTHOR]

Significant land use changes, mainly due to the growth in tourism and coastal urbanization, may be accompanied by profound alterations of the balances related to coastal sediment transport phenomena. This can cause imbalances in coastal areas with the development of zones characterized by erosion. Both structural and non structural methods for coastal protection (breakwaters, seawalls, beach nourishments) are a valid response for the mitigation of coastal erosion. In the last decades an important role in coastal protection has been assigned to submerged vegetation. The objective of this paper is to evaluate the effects of coastal vegetation on the fluid structure and velocity modifications. The work was carried out experimentally in an oscillating water tunnel. Velocities were measured using a 2C Digital Particle Image Velocimetry (DPIV) system. Vegetation was modeled by rigid cylinders. A dataset of phase averaged velocity profiles have been analyzed, for coastal hydrodynamic conditions corresponding to disturbed laminar and intermittently turbulent regimes. The analysis of velocity profiles have shown that vegetation induces modifications in the velocity distribution, causing a reduction of the phase average velocity respect to the no-vegetated bottom case, confirming the expectation, namely the influence of vegetation on the boundary layer properties. [ABSTRACT FROM AUTHOR]

A model and field investigation of hydrodynamic processes and morphological change at a sand-substrate tidal inlet is presented in order to describe conditions that can lead to shoaling and channel constriction. The Coastal Modeling System (CMS) developed at the Coastal and Hydraulics Laboratory of the U.S. Army Engineer Research and Development Center (ERDC) employs a depth-integrated two-dimensional circulation and sediment transport model, CMS-Flow, coupled with a phase-averaging, steady-state wave model, CMS-Wave, to simulate hydrodynamics and morphodynamics at Moriches Inlet in Long Island, New York. Short-term model simulations were conducted with measured water surface elevation and time-varying wave forcing to examine the capability of the model to simulate storm versus typical forcing. Model calibration and verification was performed by comparing calculations to measured water surface elevation and current velocity data collected during a field study at Moriches Inlet in 2004. Shoal development and relative movement of morphological features were reproduced in the model simulations. During simulated storm conditions, a vortex with a weak velocity field off the tip of the east jetty caused sediment to accumulate on the eastern boundary of the inlet channel. The alignment of the channel prevents the shoal from being scoured clear of the jetty. These modeled results were verified by observed morphologic response of Moriches Inlet to extratropical storms consisting of shoaling and channel constriction along the flank of the entrance channel and inlet throat. A 14-month long-term simulation also reproduced observations of channel infilling on the outer channel and accretion on the ebb tidal delta. [ABSTRACT FROM AUTHOR]

Robust and reliable formulas for predicting bed load and suspended load were developed for application in the nearshore zone where waves and currents may transport sediment separately or in combination. Also, a routine was included to determine the sediment transport in the swash zone, both in the longshore and cross-shore directions. An important objective of the development was to arrive at general sediment transport formulas suitable for a wide range of hydrodynamic, sedimentologic, and morphologic conditions that prevail around coastal inlets. Thus, the formulas yield transport rates under waves and currents, including the effects of breaking waves, wave asymmetry, and phase lag between fluid and sediment velocity for varying bed conditions. Different components of the formulas were previously validated with a large data set on transport under waves and currents, and in the present paper additional comparisons are provided for the complete formulas using data on longshore and cross-shore sediment transport from the laboratory and the field, encompassing the offshore, surf, and swash zones. The predictive capability of the new formulas is the overall highest among a number of existing formulas that were investigated. The complete set of formulas presented in the paper is collectively denoted the Lund-CIRP model. [ABSTRACT FROM AUTHOR]

Gravel pits created by anchor hopper dredging may affect regional sediment transport patterns by trapping sediments. In turn, this may cause -or enhance- erosion at the adjacent coastline. Reliable assessment of such impacts requires a good understanding of the hydro-sediment dynamic processes acting at dredged pits. This paper examines the processes for sand re-suspension from pressure, current and turbidity data collected inside and outside a single dredged pit, in a non-tidal environment (Tromper Wiek, Baltic Sea). The data confirm the generally weak sediment dynamics in the area, with waves being the main hydrodynamic agent for sediment re-mobilization. Comparisons with historical data indicate a small number of sediment re-suspension events (<15%), over a 37 months-long period, without significant difference inside and outside the pit. Suspended sediment concentration profiles are predicted inside the studied pit by a simplistic model, tuned to over-estimate sediment re-suspension. The results suggest that the depth of the excavation should be very shallow (<1 m) for the bed material to be frequently extracted out by waves, and redistributed over the area. With pits up to 7 m-deep within the extraction zone, we conclude that a significant fraction of sediment is trapped over the long-term period (years). [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]

The short-term dynamics of a dredged tidal sandbank (the Kwinte Bank, southern North Sea) are examined, on the basis of field measurements and ID sediment transport modelling. The field measurements include current data from shipborne Acoustic Doppler Current Profiler (ADCP) and from moorings (ADCP and electromagnetic S4), collected across the bank during a nominal (spring) tidal cycle, and during 7 tidal cycles, respectively. The dynamics of the bank are described in terms of tidally-averaged (residual) currents and (net) bedload transport. The results indicate a predominance of ebb flow during the period of study. Convergence of (net) bedload transport is predicted, from both flanks towards the crest of the bank. The exact location of the sand transport convergence zone varies, in the short-term, according to the prevailing tidal currents. The observation of clockwise veering of the peak ebb and flood currents over the bank indicates that this sediment transport pattern relates, at least partially, to tidal rectification of the flow. In relation to dredging, the present study suggests that the presence of a (dredged) depression at the crest of the bank influences locally the short-term hydrodynamics. The currents are channelised, and the across-bank peak (near-bed) flow is enhanced towards the crest. Net erosion of the depression is predicted, over the tidal cycle considered. More data are needed to evaluate the morphological evolution of the trough over the long-term. [ABSTRACT FROM AUTHOR]

Study of suspended sediment transport in an estuary affected by tidal bore is important for coastal engineering and management because the tidal bore can cause strong sediment resuspension and scour in shallow waters. Numerical modeling of suspended sediment transport in a natural estuary affected by tidal bore is such a challenging research topic that there are few articles on the subject available in the literature. In this study, a two-dimensional, numerical model was developed to investigate suspended sediment transport induced by a tidal bore. The hydrodynamic component of the model employs the Godunov-type scheme with second-order accuracy in space, which effectively describes the rapid supercritical flow and sharp horizontal pressure gradients of the tidal bore. To preserve balance between the source terms and the internal forces, both the water level-bottom topography formulation (WLTF) method and a special technique for triangular mesh have been applied to solve the source term in the model equations to account for the irregular bottom topography. The wet/dry boundary issue was solved by using the improved exact-Riemann solver on the dry bed. The coupled sediment transport model incorporates more reliable equations from recent publications to characterize the rapid increase of sediment resuspension in the water column. The model test against an analytical solution of convection transport shows that the sharp gradient of scalar transport is satisfactorily estimated in the model simulations. The model in the application has been validated to simulate hydrodynamics and suspended sediment transport affected by a tidal bore in the Qiantang River of China. The results compare well with a time series of observations to characterize the rapid increases of surface elevation, currents, and suspended sediment concentration resulting from the tidal bore. Results of spatial distributions of water levels and currents indicate that the model adequately describes the sharp horizontal gradients of the surface elevation and the tidal currents during the passage of the tidal bore and characterizes the suspended concentrations in the estuary. [ABSTRACT FROM AUTHOR]

Numerical modeling of dredged pits is conducted to investigate the hydrodynamic and morphodynamic interaction in offshore sand extractions. Based on an analytical formulation, a semianalytical numerical model (MEMPITS) has been developed to study the morphodynamic evolution of offshore (ho . 20 m) sand borrow areas. The numerical model has been applied to study the morphodynamic evolution of two offshore sand borrow areas in the Balearic Islands (Spain). Field data allowed a detailed characterization of the evolution of the sandpits. Time series of local hydrodynamics have been obtained using generation models (hindcast) combined with local wave and flow models. A verification of the simple model has been carried out using relatively slight adjustments to the calibration factors. The simple model provides good estimates of the infill rate and migration velocities of the offshore pits on the scale of years. This semianalytical tool allows a quick systematic investigation of the physical mechanisms as well as a etailed sensibility analysis regarding the pit design parameters. These parameters include location (water depth), pit length, width, depth, and orientation with respect to the mean flow. A nondimensional analysis based on the model is also carried out to explore the role of the different variables involved in the evolution of offshore sandpits. Based on the field data and the nondimensional analysis, some basic design recommendations for offshore sandpits are proposed. [ABSTRACT FROM AUTHOR]

The behaviour of sediment fluxes is currently less well understood in the inner-surf and swash zones than farther seaward. In the present study, field measurements were obtained of cross-shore velocity and suspended-sediment concentration from 6 and 13 heights above the bed, respectively, between the breakpoint and the shore of an intermediate- to-reflective beach, over a range of hydrodynamic conditions, to examine the cross-shore structure of sediment flux and the physical mechanisms responsible for the observed patterns. Particular attention is given to the innersurf and swash zones, which are known to contain sediment-transport processes poorly predicted by models based on velocity moments. The cross-shore structure of the depth-integrated, suspended sediment flux is found to vary according to the forcing conditions considerably more in the inner-surf and swash zones than in the outer surf and shoaling zones. In high-energy conditions, fluxes are dominated by a large offshore peak in the outer swash zone, and in low-energy conditions, fluxes are dominated by weak onshore values increasing shorewards. Examination of the temporal and vertical structure of the velocity, sediment concentration, and flux within individual events where offshore transport was dominant reveals that near-bed suspended sediment responds just as readily to mid-watercolumn velocity shear as to boundary-layer shear. Examination of events in which onshore transport was dominant reveals that near-bed suspended-sediment concentration responds more readily to near-bed horizontal acceleration than to absolute values of near-bed velocity. [ABSTRACT FROM AUTHOR]

Using mooring hydrodynamic observation, cross-shore profiles, and topographic-map and satellite-image comparisons, this study shows dramatic coastal erosion on the Qinhuangdao coast (northeast Bohai Sea, China) between 1986 and 2000, with an average retreat rate of 3.7 m/y. While the retreat rate during 1996-2003 decreased to 1.5 m/y, serious coastal erosion was found around river mouths, such as the Tang, Dai, Yang, Dapu, and Renzaohe Rivers, as well as Qilihai Lagoon, with the maximum of >7.0 m/y. Sediment starvation induced by dams mainly caused this fast coastal retreat. Sediment flux of the Luan River, the dominant fluvial sediment source in the study area, declined to only 9.0% of the levels before the impoundment of two large dams in 1979. Sharply reduced sediment supply disrupted the stability of sediment transport as well as the beaches' self-recovery processes after storm surges. Coastal erosion was further intensified by coastal engineering and tourism activities. [ABSTRACT FROM AUTHOR]

The impact of commercial vessels on coastal hydrodynamics and sediment movement has been measured and simulated in shipping channels and rivers. However, little empirical data exist on the temporal variation in vessel-generated forces in addition to the ecological implications for natural waterways such as tidal creeks and bayous. Along the U.S. Gulf of Mexico coast, these ecosystems may be highly susceptible to unnatural currents created by commercial vessel traffic. We sought to characterize and quantify the impact of large vessel traffic in the Gulf Intracoastal Waterway (GIWW) on tidal creek hydrodynamics at Aransas Wildlife Refuge (ANWR). Creek water level was monitored at 1-minute intervals in three different tidal creeks at ANWR during the summer of 2004. We also conducted preliminary measurements of bedload sediment flux associated with vessel passages. Vessel-induced fluctuations in water level in at least one site were the equivalent or greater than the diurnal tidal range (about 0.1 m) and were driven by distance to the GIWW, presence of islands as barriers, and baywide water levels that affected the attenuation of drawdown currents across a shallow bay. Bedload sediment flux during barge-induced outflow (mean = 9.3 g dry weight [dw] min-1) was nearly twice the mean measured during normal ebb outflow (5 g dw min-1). Our results identify a potentially important factor that may affect the long-term sustainability of the marsh and tidal creek systems at ANWR, which serve as wintering habitat to the endangered whooping crane (Grus americana L.). [ABSTRACT FROM AUTHOR]

Measurements of longshore sand transport, wave breaker height, longshore current velocity, and water temperature and salinity were carred out on a subarctic beach under varying water temperature conditions during summer and fall. Water temperature during summer varied from 9°C to 17°C, while temperature ranged from -1.75°C to 1.25°C during the fall experiments. During periods with low water temperatures, considerably higher rates in both bedload and suspended sediment transport were observed compared with the results obtained during summer with similar wave heights and current velocities. The increase in suspended sediment transport associated with low water temperatures is likely due to lower sediment fall velocities resulting from significant increases in fluid kinematic viscosity, which ranged from 1.1 to 1.37 × 10-6 m2 s-1 in summer and from 1.74 to 1.92 × 10-6 m2 s-1 in the fall. Less but still significant increase in bedload sediment transport in cold water is interpreted to be the result of temperature-induced variations in fluid viscosity that affect turbulence and boundary layer dynamics as well as bed configuration. Frazil ice occurred on some occasions during the fall experiments, but with the small number of samples collected when frazil ice crystals were present in the water column, it was not possible to establish a relationship between sediment transport rates and the presence or absence of ice. Our results nevertheless indicate that in cold climate regions extremely low water temperatures may cause a substantial increase of coastal sediment transport. [ABSTRACT FROM AUTHOR]

In order to understand regional variations in coastal behavior on Prince Edward Island, Canada, we investigated the role of Milne Bank, a submarine bank at East Point, the eastern tip of the island. The objective was to determine how the bank might facilitate transfer sediment from the eroding north coast to the adjacent sediment-rich south coast. The study utilized grain-size and seismic data collected on Milne Bank in 1989 and multibeam sonar surveys in 1997 and 1999. The disturbing effect of East Point on the hydrodynamic regime controls sediment transport. The northern boundary of the bank is a steep sand wave located where southward tidal and wave-driven currents rounding East Point suddenly decelerate. Sand from the north coast enters Milne Bank and is carried south in a field of migrating sand waves that are shed from the northern bounding sand wave toward the prograding end of the bank. Milne Bank is a major sediment sink, rather than a link between the eroding north coast and the sediment-rich south-facing coast. Longshore transport in nearshore bars is more likely to be responsible for continued sediment accumulation on the south coast. Embayments on the south coast have filled up in a cascading fashion, each one facilitating sediment bypassing when it has reached full capacity. [ABSTRACT FROM AUTHOR]

The Atchafalaya Bay system consists of a series of five shallow bays in southern Louisiana (U.S.A.) that are dominated by the circulation of the Atchafalaya River plume. Winter cold fronts have a significant impact on the resuspension and transport of sediments in this region, and a better understanding of the circulation during these events is absolutely necessary for determining the sediment transport patterns of the Atchafalaya Bay system and the adjacent shelf area. Understanding the circulation of this region is also crucial for environmental studies as well. This work describes the implementation of the Navy Coastal Ocean Model (NCOM), a three-dimensional numerical circulation model for tide, river, and wind-forced circulation in the Atchafalaya Bay system. The model has a cell size (Δx) of ∼800 m and is nested to a northern Gulf of Mexico model (Δx ∼ 5000 m), which is itself nested to the global NCOM (Δx ∼ 1/8°). Atmospheric forcing is supplied by the Navy Operational Global Atmospheric Prediction System (NOGAPS) (Δx = 1°). These models are used to simulate the hydrodynamics of the Atchafalaya Bay system and Atchafalaya river plume between December 1997 and January 1998 during the passage of three winter cold fronts. The water levels, salinity, and currents predicted by NCOM are in reasonable agreement with available measurements and tide-gauge elevation data. Errors in ebb tides and wind-driven circulation are attributable to uncertainties in the bathymetry and the low spatial and temporal resolution of the NOGAPS wind fields. [ABSTRACT FROM AUTHOR]

Coastal dynamics and shoreface relief in ice-free seas are a function of hydrodynamic interactions between the sea and bottom sediments. In the Arctic, additional, cryogenic factors such as permafrost and the action of sea ice influence coastal processes. The goal of our paper is to assess this influence, mainly on the profile shape. Mathematical analyses of the shape of 63 shoreface profiles from the Laptev, Beaufort, and Chukchi Seas were carried out. The shapes of Arctic shoreface profiles and those of ice-free seas are compared. We found that large ice and silt content in perennially frozen sediments composing Arctic coasts favor their erosion. Sea ice plays an important role in sediment transport on the shoreface and correspondingly changes shoreface relief significantly. Some effects of ice intensify coastal erosion considerably, but others play a protective role. The overall influence of cryogenic processes on Arctic coasts composed of loose sediments is seen in that the average rate of coastal retreat is larger than in the temperate environments, even though Arctic coasts are protected by a continuous ice cover most of the year. The shape of the shoreface profile in the Arctic does not differ from that in ice-free seas, and is satisfactorily described by the Bruun/Dean equilibrium profile equation. The explanation of this fact is that all changes of the profile shape, caused by cryogenic processes, are short lived and quickly eliminated by wave action. [ABSTRACT FROM AUTHOR]

Marsh surface deposition, suspended sediment concentrations, tidal hydrodynamics, and marsh surface characteristics were measured within a tidal creek system of a west-central Florida, microtidal, open marine Juncus roemerianus marsh to examine the depositional relationship between a creek system and the surrounding marsh during nonstorm conditions. Results suggest that short-term marsh deposition is highly episodic with deposition showing an inverse relationship with marsh surface inundation. Deposition was greatest at marsh sites adjacent to secondary creek segments over all examined timescales. Variations in hydroperiod, time-velocity asymmetry, vegetation density, and sediment availability could not explain the observed differences in short-term deposition. [ABSTRACT FROM AUTHOR]

Hydrodynamic measurements and analysis of suspended sediments were conducted in the coastal area to reveal the source and dispersal processes of muds accumulating in Jinhae Bay, one of the largest bays in the Korea Strait. A number of hydrographic stations in the bay were occupied in order to obtain time series of suspended sediment concentrations, currents, water level, temperature, and salinity for one or two tidal cycles. The results, measured in May through October, suggest that a slight net influx of suspended sediments into the bay occurs consistently under low-wave, microtidal conditions. They also show a passageway of suspended sediments selectively through an entrance facing the open sea. The hydrodynamic measurements, together with tidal current pattern and landsat image of the suspended plume in the Korea Strait, indicate that the mud in Jinhae Bay has been fed largely by the adjacent Nakdong River, rather than by offshore sources. [ABSTRACT FROM AUTHOR]

A cross-shore profile evolution model, Uniform Beach Sediment Transport-Time-Averaged Cross-Shore (UNIBEST-TC), is used in the present study. The model was developed at WL/Delft hydraulic laboratory in the Netherlands and comprises a conglomerate of submodels representing identified processes of cross-shore sediment transport. Validation of UNIBEST-TC was carried out using the collected field data at the Egmond site in the Netherlands and at the Duck site in the US. The model is capable of predicting wave height and wave direction for both sites (Egmond site and Duck site). The prediction of long-shore current is reasonable for the Egmond site, but it is unsatisfactory for the Duck site. The difference between the measured and the predicted values for long-shore current and cross-shore current is partly due to the difference between the measured values, which are at a certain depth, and the predicted values that are depth-averaged velocity. Beside that, the turbulence in the breaker zone leads to errors in the measurements, which could be another factor. It is shown in the present study that on relative small scales, opposite morphological behavior is present. Therefore, morphodynamic profile modeling requires a representative characteristic bottom profile. To achieve a qualitative data for the calibration of the model, it is suggested that field measurements should include error ranges. Furthermore, the effect of small variations of the water depth on the processing of the signals should also be taken into account. [ABSTRACT FROM AUTHOR]

The possible influence on swash-zone sediment transport of hydraulic jumps is investigated using field measurements from two natural beaches in high-energy (Hs = 1.5 to 3.7 meters) dissipative conditions. Results from measurements of cross-shore velocity using electromagnetic current meters at z = 3 centimeters, water depth using pressure transducers at z = 0, and cross-shore bore displacement using video time stacks suggest that hydraulic jumps may occur in approximately one-third of infragravity backwashes. Results from sediment load measurements using traps suggest that backwashes containing jumps can advect approximately 2.5 times as much sediment offshore than a backwash not confining a hydraulic jump. The overall effect of hydraulic jumps appears to be to enhance offshore transport, especially in high-energy conditions, when infragravity backwashes are more common. [ABSTRACT FROM AUTHOR]

A port complex was implanted in the coast region of Suape, PE-Brasil, in 1979–80, which altered the geomorphological and hydrodynamic conditions of the area, mainly in the estuary of the Ipojuca River. Water samples were collected from the surface and the deep layer to determine the salinity, pH, dissolved oxygen, transparency, and temperature from three fixed stations in the estuary of the Ipojuca River during the summer and winter before (1978) and after (1986–87) the port's construction, in order to evaluate the effects of the port-induced changes. The data were subjected to a principal component analysis and to individual t tests. The first principal component, the axis of maximum information, alone explained 50% of the total variance, being associated with the generalized increase of the chemical parameters after the port's construction, mainly the salinity. Despite the fact that the results of the t tests presented significant differences only for the dissolved oxygen, pH, and temperature, the increased salinity produced the greatest ecological effects in the estuary. The water flow of the Ipojuca River was diverted toward the ocean, decreasing the river-flow velocity at the mouth. This decrease in flow caused a sedimentation in the area, a decrease in the circulation and depth, and a transformation of the mouth of the river into a coastal lagoon with an increase in evaporation and salinity. A delay of more than 2 hours was observed in the dynamic tide in relation to the normal 6-hour cycles. Despite an increase in the concentration of dissolved oxygen and transparency values, effects that theoretically improve environmental conditions, a morphological transformation occurred that caused drastic changes in the estuary's circulation and in the tidal currents. [ABSTRACT FROM AUTHOR]

The impact of beach nourishment on the development of coastal dunes was studied along the Dutch coast. A database of annual cross-shore profiles was analysed to derive volumetric changes associated with aeolian and hydrodynamic processes. The database covered a period of 15 years. Beach nourishment projects that were carried out arbitrarily within this time-span were selected, and the volumetric changes occurring on the selected sites were statistically related to the number of years following nourishment. An overall negative sand budget was found for the supratidal zone of the nourished sites. A substantial part of the sand was blown to the foredunes. One year after nourishment, this amount increased significantly. At the same time, the supratidal beach was eroded more. In the second and third year after nourishment, the erosion of the higher parts of the nourishment decreased. In the foredune, dune toe erosion due to storm surges was usually negligible until the fourth year following beach nourishment. Thus, beach nourishment temporarily protected the adjacent foredunes from being eroded by periodic wave attack, and also temporarily enlarged the aeolian sand transport rate to the dunes. [ABSTRACT FROM AUTHOR]