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Liu, Z.; Zang, J., and Liu, J., 2023. Preliminary analysis of reclamation changes in Macao using multisource and multitemporal remote-sensing data. Journal of Coastal Research, 39(1), 90–102. Charlotte (North Carolina), ISSN 0749-0208. Macao is a typical reclamation city. A systematic analysis of reclamation changes can be used to relate reclamation to socioeconomic development. In this study, multisource and multitemporal satellite remote-sensing data were used to analyze the temporal and spatial characteristics, driving forces for reclamation, and nearshore water quality of Macao. The results showed that the Macao coastline is moving towards the sea. The total area of Macao increased from 29.19 km2 in 1999 to 35.83 km2 in 2019. The largest proportion of reclamation land-use type was public facilities land, whereas the smallest proportion was green land and square land. The land distribution gradually became more compact up to 2007 and dispersed thereafter. The factors of population, gross domestic product, number of visitors to Macao, and total export trade had different influences on reclamation in Macao during different time periods, where the population factor had the largest overall impact. The concentrations of chlorophyll and suspended sediment in Macao coastal waters were high nearshore and low offshore. [ABSTRACT FROM AUTHOR]

Windom, H.L. and Palmer, J.D., 2022. Changing river discharge and suspended sediment transport to the Georgia Bight: Implications to saltmarsh sustainability. Journal of Coastal Research, 38(3), 512–522. Coconut Creek (Florida), ISSN 0749-0208. Suspended sediment delivered in river discharge to the Georgia Bight (the coastal-shelf area of the SE U.S. Atlantic coasts of Georgia and South Carolina) provides a continuous supply of fine grain sediments to support coastal saltmarshes. Archived data on discharge and suspended sediment loads for Piedmont and Coastal Plain rivers collected over eight to nine decades were used to estimate the present rate of sediment discharge to the Bight to be about 1 × 106 metric tons annually. The data used in this assessment are for the period after major reservoir/dam construction and other streamflow diversions occurring during the 1950s–1970s, which had a major effect on sediment yields of SE Atlantic watersheds. The estimated annual sediment delivery is about two-thirds of that needed to maintain vertical saltmarsh stability as sea level rises at the present regional rate of 3.3 mm/y. The observed 2% per decade decreasing trend in river discharge to the Bight, related to rapid population and temperature rise since ca. 1960, and the continual depletion of sediment stored in river floodplains below dams, suggests that the fine sediment supply to the coast will continue to decline. [ABSTRACT FROM AUTHOR]

Briggs, T.R.; Figlus, J.; Torres-Freyermuth, A.; Puleo, J.A.; Warren, W., and Alrushaid, T., 2020. Variability in onshore sediment transport on a natural beach during a Central American cold surge event. Journal of Coastal Research, 36(3), 487–497. Coconut Creek (Florida), ISSN 0749-0208. Beaches facing the Gulf of Mexico along the northern part of the Yucatan Peninsula experience frequent Central American cold surge events, or northerly storms locally called "Nortes," which interrupt the usual daily patterns of sea- and land-breeze–dominated nearshore dynamics. These perturbations of prevailing hydrodynamic forcing conditions also affect sediment distribution and transport parameters in the surf and swash zone, which are critical elements in understanding and modeling complex morphodynamic processes during storm events. However, detailed measurements of sediment characteristics throughout the water column during a storm event are scarce. This study presents field measurements of bottom and suspended sediment transported in the onshore direction during a 24-hour storm event impacting the Yucatan Peninsula. Sediment load data within the water column collected in 3 hour intervals via vertical arrays of streamer traps, deployed at two cross-shore locations in the inner surf zone, are compared with sediment data from collocated bottom grab samples. Time series of grain size distributions, sediment statistics, and respective vertical variations throughout the water column are related to measured bed-level changes to verify applicability of simple erosion and accretion predictors. Results indicate that bottom sediment and sediment distributions throughout the water column deviate substantially due to storms, highlighting the complexity and difficulty of assessing sediment transport and morphodynamic processes with a single-parameter sediment characteristic. Calculated total onshore transport rates during the Norte were on average one order of magnitude higher than during nonstorm conditions. [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]

Li, C.; Fu, X.; Xiao, Q.; Pan, X., and Cao, H., 2018. Vertical distribution of sediment concentration in offshore waters. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 167–171. Coconut Creek (Florida), ISSN 0749-0208. The existing formulae of vertical distribution of sand concentration are difficult to integrate. Based on the formula of vertical distribution of the flow velocity obtained in the previous study and the suspended sediment diffusion equation in equilibrium, a formula of the distribution of suspended sediment is deduced. It can effectively avoid the phenomena that the Rouse formula equals zero at the water surface. The field measurement data of Jiangsu Sea is used to verify and analyze the deuced formula. And results show that it has a high accuracy and it solve the difficulties caused by lack of data in engineering, such as only the sediment concentration on the surface is given. [ABSTRACT FROM AUTHOR]

ABSTRACT Tao, J.; Xu, F.; Yao, P.; Zhou, Z., and Zhang, C., 2018. The variations of sediment transport patterns in the radial sand ridges along the Jiangsu coast, China over the last 30 years. 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. 216–220. Coconut Creek (Florida), ISSN 0749-0208. The research objective is to clarify the primary factors lead to the variations of the suspended sediment transport in the radial sand ridges (RSRs) along the Jiangsu Coast over the last 30 years. The suspended sediment concentration (SSC) fields measured in several field surveys from 1980 to 2010 were analyzed. The field data indicate that the SSCs in 1980 are higher than those 2010. A two-dimensional numerical model was developed to simulate the inter-annual variations of the suspended sediment transport. Generally, the magnitude of the SSC is highly relevant with the current speed, which peaks around the Old Yellow River Delta (OYRD) and in the central RSRs. However, the northern part of the RSRs indicates higher SSC than the southern part, which is attributed to their different bed sediment composition. The net suspended sediment flux was calculated. In the north of the RSRs, the sediments are transported in the south direction, which implies a sediment input from the OYRD to the RSRs. In the south of the RSRs, a net sediment loss was observed, which is consistent with the decreasing of the sediment flux from the Yangtze River. The simulated suspended sediment transport in 1980 and 2010 mutually show similar spatial patterns, while SSCs in 1980 are overall larger than those in 2010. It is concluded that the decrease of the SSCs from 1980 to 2010 is attributed to the reduction of the OYRD and the large-scale reclamation along the Jiangsu coast, while the sediment fluxes from the Yangtze River is less important. [ABSTRACT FROM AUTHOR]

Park, D.; Kim, H.; Lee, S.; Lee, J., and Yoo, J., 2018. Simulation of storm-induced cross-shore sediment transport at Anmok Beach with wave-resolving CST3D-WR. 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. 1001–1005. Coconut Creek (Florida), ISSN 0749-0208. An intensive field survey was carried out before and after a typhoon Goni at Anmok Beach, east coast of Korea, where a submerged breakwater exists. Survey items include offshore wave height, direction, and period; nearshore wave height, direction, and period, current and water level, bed load and suspended sediment load; bathymetry; and shoreline position. Interesting bathymetric change was observed after the typhoon: offshore sediment transport and consequent bathymetric change happened along the most coastline. The data exhibit the impact of the typhoon clearly, A wave-resolving numerical modelling system CST3D-WR was applied to the site for the typhoon situation, and qualitatively well reproduced the field bathymetric change. [ABSTRACT FROM AUTHOR]

Kim, D.-H,; Kim, B., and Choi, B., 2018. Adaptability of suspended sediment transportmodel for sandbar migration simulation. 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. 661–665. Coconut Creek (Florida), ISSN 0749-0208. Adaptability of a nonequilibrium suspended sediment transport model to flow and morphological conditions was studied. Under dispersive and unsteady flow conditions, four sets of numerical simulations were conducted using a morphodynamic model. The flow fields were modeled using the Boussinesq equation and the bottom evolutions were modeled using the transport equation for the suspended load and the bed load formulae. Numerical simulations using a constant suspended parameter and variable bed load parameters within a multiple of reference values yielded very similar predictions. These similarities resulted from the adaptability of the suspended sediment transport model which considered the flow and morphological conditions; although the use of different values of bed load parameters resulted in different individual contributions to the bed load fluxes by the parameters, the suspended sediment model adjusted the suspended load flux and made total fluxes converged. The same results were observed in the bottom evolution rates. On the other hand, successful results could not be obtained in the opposite cases: with fixed bed load parameter and variable suspended load parameter. [ABSTRACT FROM AUTHOR]

Ha, H.K.; Seo, J.Y.; Jung, Y.H.; Ha. H.J.; Kim, S.B.; Kang, J.W.; Kim, Y.H., and Ryu, J., 2018. Dynamics of sediment resuspension in the inner harbor under different forcing conditions: A case study of Ulsan, Korea. 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. 451–455. Coconut Creek (Florida), ISSN 0749-0208. Bottom mooring data of currents and backscatter strength derived from a 1200-kHz acoustic Doppler current profiler were collected in the inner Onsan Harbor, Ulsan during the summer season (July 5 to August 5, 2016). The mean volume backscattering strength (MVBS), which is a proxy of suspended sediment concentration (SSC), continued to exhibit distinct signatures of sediment erosion (or resuspension) under different forcing conditions such as tides, winds, and precipitation. Results exhibit the different patterns of sediment resuspension between spring and neap tides. During spring tide, the extensive tidal forcing provided a favorable condition to resuspend sediments trapped near the bed. The MVBS with high SSC was consistently recorded. During neap tide, on the other hand, the MVBS with high SSC was intermittently recorded, which was related to the strong wind events. While the flow was being intensified by winds, the short-lasting (2–4 hours) sharp spikes of MVBS were observed. The stratification developed by increased precipitation might cause to block the upward transport of sediments near the bed, even though the strong winds (>13.6 m s−1) lasted over 4 days. These outcomes could give insight into the complexity of hydrodynamics and sediment transport occurring in the harbor where various natural and artificial forcings are combined. [ABSTRACT FROM AUTHOR]

Xu, B.B.; Gong, Z.; Zhang, Q.; Zhang, C.K., and Zhao, K., 2018. Non-equilibrium suspended sediment transport on the intertidal tidal flats of Jiangsu coast, China. 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. 251–255. Coconut Creek (Florida), ISSN 0749-0208. Accurate modelling of instantaneous sediment transport processes in coastal environments has been a great challenge for many decades. One of the difficulties comes from the existence of time lag between flow and sediment transport, termed as "the non-equilibrium transport effect". To better understand and simulate the sediment transport processes, field observations were conducted on the middle intertidal flats of Jiangsu coast. Water depths, current velocity profiles, wave parameters, stratified suspended sediment concentrations (SSC), as well as grain sizes of both suspended sediment and bed sediment were measured. Results show that suspended sediment has an average grain size of 11.2 μm, the percentage of cohesive suspended sediment can be up to 97%. The bed load has an average grain size of 40 μm, the percentage of cohesive sediment is only 76%. The measured maximum SSC occurs at the beginning and the end of each tidal cycle. It is well-mixed during flood and ebb peak, but stratified during slack period. The vertical equilibrium SSC profiles were calculated based on the advection-diffusion theory. Calculated equilibrium SSC is well-mixed during whole tidal cycle and is controlled by the local hydrodynamics. The difference between calculated equilibrium SSC and real ones indicates that the contribution of advection is dominant. Thus the non-equilibrium suspended sediment transport processes should be taken into account for intertidal flat evolution. [ABSTRACT FROM AUTHOR]

Tao, J.; Xu, F.; Yao, P.; Zhou, Z., and Zhang, C., 2018. The variations of sediment transport patterns in the radial sand ridges along the Jiangsu coast, China over the last 30 years. 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. 216–220. Coconut Creek (Florida), ISSN 0749-0208. The research objective is to clarify the primary factors lead to the variations of the suspended sediment transport in the radial sand ridges (RSRs) along the Jiangsu Coast over the last 30 years. The suspended sediment concentration (SSC) fields measured in several field surveys from 1980 to 2010 were analyzed. The field data indicate that the SSCs in 1980 are higher than those 2010. A two-dimensional numerical model was developed to simulate the inter-annual variations of the suspended sediment transport. Generally, the magnitude of the SSC is highly relevant with the current speed, which peaks around the Old Yellow River Delta (OYRD) and in the central RSRs. However, the northern part of the RSRs indicates higher SSC than the southern part, which is attributed to their different bed sediment composition. The net suspended sediment flux was calculated. In the north of the RSRs, the sediments are transported in the south direction, which implies a sediment input from the OYRD to the RSRs. In the south of the RSRs, a net sediment loss was observed, which is consistent with the decreasing of the sediment flux from the Yangtze River. The simulated suspended sediment transport in 1980 and 2010 mutually show similar spatial patterns, while SSCs in 1980 are overall larger than those in 2010. It is concluded that the decrease of the SSCs from 1980 to 2010 is attributed to the reduction of the OYRD and the large-scale reclamation along the Jiangsu coast, while the sediment fluxes from the Yangtze River is less important. [ABSTRACT FROM AUTHOR]

Lu, C.Z.; Li, H.; Dai, W.Q.; Tao, J.F.; Xu, F.; Cybele, S.; Zhang, X.Y., and Guo, H.T., 2018. 3-D Simulation of the Suspended Sediment Transport in the Jiaojiang Estuary: Based on Validating by Remote Sensing Retrieval. 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. 116–120. Coconut Creek (Florida), ISSN 0749-0208. Suspended sediment concentration (SSC) in Jiaojiang Estuary is characterized by high concentration and significant diurnal dynamics. The large-scale reclamation will influence the sediment transport in Jiaojiang Estuary. At present, ship-borne data, remote sensing observations, and numerical modeling technique are the main technological methods to acquire the distributions of SSC. However, every method has its own limitations in application. Conventional ship-borne survey requires a lot of manpower and resources to obtain sediment distribution of an estuary although its accuracy is high. The cloudy and rainy environment has been the bottle-neck for monitoring the land and ocean surface. With the influence of land-use by human activities (such as tidal flats reclamation) being strengthened gradually, previous numerical models are not suitable for the new environment. This paper aims to combine numerical modeling technique with remote sensing observations to acquire a higher-resolution surface suspended sediment field in time and space. MIKE3 3D model was used to simulate the suspended sediments and it is composed of hydrodynamic module and mud transport module. The surface-layer sediment distribution was calculated using suspended sediment dynamic mathematical model in MIKE 3. Based on Geostationary Ocean Color Imager (GOCI) and the simultaneous surface layer sediment concentration data, a remote sensing model was developed to retrieve the distribution of SSC in the Jiaojiang Estuary. The degree of matching between the remotely sensed SSC and the numerically simulated SSC is up to 72%, both of which reveal temporal-spatial variation of the SSC. The research provides a reference for real-time monitoring and forecasting the dynamic variation of the SSC. [ABSTRACT FROM AUTHOR]

Simionato, C.G. and Moreira, D., 2018. Modeling the processes that control fine sediments transport in the Río de la Plata Estuary. 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. 31–35. Coconut Creek (Florida), ISSN 0749-0208. Numerical models are excellent tools for conducting process studies and testing hypotheses based on observations. They constitute a "virtual laboratory" in which the forcings can be set "on" or "off", or even the environmental conditions can be modified. The Rio de la Plata (RdP) is one of the most turbid estuaries in the world and the one most important in terms of continental discharge and drainage area. Observations of suspended fine sediments, particularly those remote and in situ collected on recent studies, have driven to the statement of several hypotheses about the processes that would determine the concentration of suspended sediments in the different parts of the estuary. Nevertheless, the relative scarcity of data do not allow to demonstrate the validity of those hypothesis and the role of several physical processes and of the morphology remain unknown. The objective of this work is, therefore, to analyze the role of the different forcing and the environmental conditions in the determination of the distribution of suspended fine sediments in the RdP applying processes oriented numerical simulations. [ABSTRACT FROM AUTHOR]

Kawanisi, K.; Zhu, X.-H.; Fan, X., and Nistor, I., 2017. Monitoring tidal bores using acoustic tomography system. Continuous measurements of flow velocities and suspended sediments were carried out in the Qiantang River (China) with extreme tidal bore conditions. Fluvial and coastal acoustic tomography systems (FATS/CATS) were used in the field studies simultaneously with acoustic Doppler current profilers (ADCPs) and optical backscatter (OBS) equipment. A couple of broadband transducers were installed diagonally across the river around 90 km upstream of the mouth. The length of the sound transmission line was 3050 m. Cross-sectional averaged velocities ( V) collected by FATS/CATS enabled the authors to estimate important characteristics of the tidal bores (bore height and celerity). The changes in V recorded during the upstream movement of the bore ranged from 1.35 to 1.76 ms−1. The height and celerity of the bore varied from 1.0 to 1.32 m and 7.59 to 8.29 ms−1, respectively. Since a point/vertical measurement cannot represent a river's cross section, the ADCP data for velocity and water level (pressure) near the riverbank underestimated the bore height by 22% and 16%, respectively. The maximum suspended sediment concentration (SSC) was observed to have occurred approximately 1 h after the bore's arrival; the time lag between the maximum SSC and the bore front is considerably larger than the time lags in previous works. In the case of larger bores, the section mean SSCs, which were deduced from the sound attenuation of FATS/CATS due to suspended sediment, appeared to be appropriate. The time history of the velocity, measured by ADCPs, during the passage of the bore deviated from the normal velocity profile, i.e. the velocity magnitude decreased with an increasing height above the bed for the relaxation time of a few minutes following the arrival of the bore. [ABSTRACT FROM AUTHOR]

Tan, C.; Huang, B.; Liu, F.; Yang, Q.; Jiang, C., and Zhang, S., 2016. Transformation of the three largest Chinese river deltas in response to the reduction of sediment discharges. The Yellow, Yangtze, and Pearl rivers deliver more than 1.2 × 1012 m3/a of freshwater and 13.6 × 108 t/a of sediment into the western Pacific Ocean, playing important roles in the morphological evolution of the ocean in this region. From the 1950s to the 2000s, the total sediment loads of the three rivers decreased by 81.2%; this change has been primarily caused by human activities, such as dam construction and water-soil conservation projects. The sediment loads in the Yellow, Yangtze, and Pearl rivers decreased by 89.9%, 62.1% and 57.1%, respectively, from the 1950s to the 2000s. In response to the sediment supply decrease, the sediment regimes of the river channels in the lower reaches of the three rivers generally transitioned from deposition to erosion since the 1990s. The erosion of the channel has modulated the characteristics of the suspended sediment delivered to the estuary; for example, the erosion of the lower river channel increased the sediment flux and caused relatively coarser suspended sediments to be delivered to the estuary. As a consequence of the changes in the river basins, the evolutions of the three river deltas have transformed in the 2000s. The subaqueous deltas of the Yellow and Yangtze rivers changed from deposition to erosion. However, the Pearl River delta generally prograded seaward, and a portion of its subaqueous delta ( e.g., the Modaomen River mouth) underwent erosion. In the coming decades, the sediment discharges into the seas from these three rivers are likely to decrease further because of intensifying human activities. Therefore, enhanced erosion in the three river deltas will continue when the river deltas remain unprotected. Our study demonstrates that human activities in the three river basins can influence the morphological changes of the estuaries, indicating that a river basin and its coastal zone are an integrated system. [ABSTRACT FROM AUTHOR]

Bezhenar R.; Jung K.T.; Maderich V., and Kim K.O., 2016. 3D numerical model of ecohydrodynamics for shallow waters. 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. 820-824. Coconut Creek (Florida), ISSN 0749-0208. A new modeling system for the calculation of ecohydrodynamics in shallow water bodies is developed. It consists of three interacting components: hydrodynamics, sediment transport and ecodynamics. The system takes into account changes in the light absorption in the water due to presence of phytoplankton and suspended sediments as well as in the bottom friction due to presence of bottom vegetation. The bottom friction in turn affects the currents and turbulence that govern the transport and dispersion of nutrients which are necessary for the growth of phytoplankton and bottom vegetation. The turbulent mixing influences the resuspension of sediments that changes absorption of light in the water, affecting the bottom vegetation growth. The influence of model feedbacks on the biochemical characteristics of shallow Lake Markermeer (the Netherlands) was studied. Results of modeling show good quantitative agreement with measurements of temperature, nutrients, and dissolved oxygen. Good qualitative agreement of bottom concentration of periphyton with measured field of bottom plants was also obtained. [ABSTRACT FROM AUTHOR]

Wang, A. M.; Wang, H. J.; Bi, N. S., and Wu, X., 2016. Sediment transport and dispersal pattern from the Bohai Sea to the Yellow Sea. Suspended sediment flux, dispersal patterns and its possible mechanisms in the Bohai Sea were investigated based on the observational data in May and November, 2012, data retrieved from MODIS imageries and the ocean current data from HYCOM. The sediment dispersal pattern and the annual net sediment flux presented evident seasonal variability. During wintertime, the prevailing strong northerly winds and the related high wave heights resuspended the sediment along the coast of the Huanghe Delta that was transported into the Laizhou Bay along its western coast and exported to the Bohai Strait through the eastern Laizhou Bay as enhanced by the coastal current. The wintertime contributed approximately 4.84 Mt of suspended sediment flux to the Yellow Sea, as higher than the flux in summertime by one order. In summertime, the less energetic environment together with the stratified water column was unfavorable to the sediment export to the Yellow Sea. As a result, the sediment delivered by the Huanghe to the sea in summertime mostly accumulated within the subaqueous delta, which acted as a primary source of sediment export to the Yellow Sea in wintertime. [ABSTRACT FROM AUTHOR]

Azhikodan, G. and Yokoyama, K., 2015. Temporal and spatial variation of mixing and movement of suspended sediment in the macrotidal Chikugo River estuary. The effect of mixing on the movement of the estuarine turbidity maximum (ETM) was examined in the highly turbid Chikugo River estuary, Japan, in consideration of four significant issues: semidiurnal and semilunar tidal variations, spatial distribution, and synchronism of data acquisition. Vertical profiles of salinity and turbidity were measured for 2 weeks at 1 km intervals from the river mouth (0 km) to 17 km upstream, with a short duration for every cruise. Spring-neap transition and the spatial variation of mixing, and suspended sediment concentration (SSC) was found during the semilunar tidal cycle. The estuary gradually changed from a vertically well-mixed condition during spring tide to a stratified condition during the neap tide via a partially mixed condition during the intermediate half tides. The relationship between the flow ratio and the SSC showed that ETM growth was dominated by both tidal forcing and freshwater flow. SSC was high when the salinity was 0.5 practical salinity units (psu) in the upper estuary and 10 psu in the lower estuary. For the same mixing strength (MS), SSC in the lower estuary was greater than that in the upper estuary. Based on flow ratio, salinity, and MS, the occurrence of the ETM and its development at the macrotidal estuary was a consequence of three processes: bed-sediment erosion by seawater in the lower estuary, sediment transport in the estuarine channel by the tidal current and freshwater flow, and sediment accumulation at the salinity front in the upper estuary. [ABSTRACT FROM AUTHOR]

Li, L.; Wu, H.; Liu, J. T., and Zhu, J., 2015. Sediment transport induced by the advection of a moving salt wedge in the Changjiang Estuary. This study focused on the intratidal variations of suspended sediment concentration (SSC) and residual sediment transport near a moving salt wedge in the Changjiang Estuary. The stratification was controlled by the advection of the salt wedge and was strengthened during the flood tide and weakened during the ebb tide. This phenomenon is the opposite of systems that are dominated by tidal straining of salinity, which diminishes the stratification during the flood tide and enhances it during the ebb tide. The enhanced stratification during the flood tide restricts turbulent mixing; hence, the resuspended sediment is concentrated below the pycnocline. Because of the stronger turbulent mixing during the ebb tide, the suspended sediment can be elevated to the surface, decreasing the near-bottom SSC. Such tidal asymmetries of mixing and near-bottom SSC cause the net sediment flux to be directed landward in the lower layers after a tidal cycle. [ABSTRACT FROM AUTHOR]

Barboza, C.D.N.; Paes, E.T.; Jandre, K.A., and Marques, Jr., A.N., 2014. Concentrations and fluxes of nutrients and suspended organic matter in a tropical estuarine system: The Tinharé-Boipeba Islands Archipelago (Baixo Sul Baiano, Brazil). Variations in the concentrations and fluxes of nutrients and suspended organic matter were examined during tidal cycles in four sectors (Barra dos Carvalhos, Barra de Boipeba, Cairu, and Galeão) of the estuarine system of the Tinharé-Boipeba Islands Archipelago (ESTBIA) on the northeastern Brazilian coast. In this study, we obtained new data by sampling and also used data from the literature (for Galeão) to estimate the exchange of nutrients between the estuary and the adjacent sea and to evaluate the factors that control these fluxes. It was observed that the factors that most influenced the nutrient fluxes in the estuarine system were the variations in the tidal prism and in the fluviometric regime. Moreover, the highest concentrations of dissolved inorganic nutrients occurred during the neap tide cycle, whereas the highest concentrations of particulates were found in the spring cycle. Organic carbon was transported in greater amounts in the dissolved form than in the particulate form, whereas nitrogen occurred predominantly in the organic form. The C : N and C : P ratios of the particulate organic material were typically high, showing a certain degree of seasonality related to the level of flooding of the mangroves. The nutrient fluxes transported in each sector showed the following tendency: Galeão ≥ Cairu >> Barra dos Carvalhos >> Barra de Boipeba. The net budgets for water and nutrients obtained for Galeão always reflected export from the estuary. In the other regions, particulate organic carbon, NO , NO , and NH were also exported from the estuary, whereas the remaining nutrients were exported during the neap tide cycle and imported during the spring cycle. [ABSTRACT FROM AUTHOR]

Bifurcations in tidal networks strongly control the distribution of flow and sediment flux over a river network system. These distributions are important in determining the fluvial sediment dispersal and transport from river networks to shorelines, thereby greatly affecting river channel, estuary, and coastal environments. Long-term observations of flow and suspended sediment division at the apex bifurcation of the Pearl River network indicate that there has obviously been more water and sediment transport into the North River network since the 1990s. Wavelet analyses of the sediment division at the apex bifurcation show that common spectral structures were dominated by annual fluctuations from 1959 to 2005. However, significant, intra-annual and annual fluctuations have been detected since the early 1990s, corresponding well with the abrupt changes in flow and sediment division. By analyzing the controlling factors (water discharge ratio ηL and suspended-sediment concentration ratio KS) of the suspended-sediment flux distribution in a braided river, we concluded that both the riverbed downcutting from intensive sand mining in the lower river and the lack of suspended-sediment supply because of dam construction in the upper river are primarily responsible for the sediment redistribution in the apex bifurcation of the Pearl River delta. Furthermore, the wavelet analysis indicates an energy growth in the signal of the suspended-sediment division ratio. The observed spectral composition was used to estimate the potential suspended-sediment division in the absence of human influences by removing the effect of that energy growth, which helped to explain the extent of the effect of intensive anthropogenic activities on the redistribution of suspended-sediment flux. The estimate indicates that there has been a decrease of 6.27 x 107 tons of suspended-sediment load flowing to the West River network for sediment redistribution at the apex bifurcation of the Pearl River delta between 1992 and 2005. [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]

Rahman, S., Mano, A. and Udo, K., 2013. Quasi-2D Sediment Transport Model Combined with Bagnold-type Bed Load Transport. Suspended load and bed load sediment transport are important component for the sediment transport in surf zone. The purpose of this study is to obtain a good model for sediment transport in surf zone by combining a quasi-2D sediment transport model and the Bagnold-type sediment transport model. The quasi-2D sediment transport model is used to simulate the suspended load transport, while the Bagnold-type for the bedload transport. A quasi-2D numerical wave model called Funwave was expanded to accommodate the sediment transport model. The model is validated by the published data for sediment transport in a wave flume. Two mode of morphological change is compared to evaluate the influence of wave-current (mode A) and instantaneous bottom velocity (mode B) in the third and forth velocity moment of Bagnold-type sediment transport model. Four sets of bed load transport parameters are evaluated to calculate bed level change. The evaluation shows that although e B exceeds one, it can produce bed level change similar to that by using the parameters proposed by Bailard. Parameters proposed by van der Molen calculated very high bed level change, while Gallagher's parameter produced relatively small bed level change. The performance of two modes of morphological change shows that mode A produce much better morphological change than mode B in surf zone for the bedload transport component. While for the suspended load component, mode B produces very high erosion in surf zone. Coupling of mode B and a wave motion-induced suspended load transport gives comparable morphological change to the experimental data. [ABSTRACT FROM AUTHOR]

The Yellow Sea is fringed with deltas and estuaries on the Chinese and Korean coasts, respectively. The Korean estuaries, rock bound on the Ha coast, are represented by the Han estuary, the largest in the eastern Yellow Sea. To reveal the relationship between extensive tidal flats and major channels in the Han estuary, suspended sediment transport was observed from the water column down to the bottom boundary layer. Transecting channels and deploying benthic tripods were accomplished at a number of critical sites during different spring tides, mostly under the fair-weather conditions of dry seasons in 2006-08. The hydrodynamic measurements unraveled the role of macrotidal currents in estuarine suspended transport. According to lateral momentum analyses, cross-channel flows were governed by two forces: rotation and surface slope. The estimations of suspended flux and lateral momentum balance elucidated that, of the two candidate channels, the Yeomha Channel dominantly supplied riverine muds to the adjacent vast Ganghwa tidal flats. The other larger channel, Sukmo, was found to displace muds up the channel to the Han River mouth. Another offshore major channel, Jangbong, revealed small suspended flux, reflecting no substantial mud input of offshore origin into the Han estuary. This study maybe timely in that most Korean estuaries have artificially developed and are facing various environmental problems. [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]

Indian Remote Sensing-P4 (IRS P4) Ocean Color Monitor (OCM) data is used to understand seasonal variations in suspended sediment (SS) dispersal pattern in the near-shore waters of the Central West Coast of India. Four distinct patterns of sediment dispersion are observed. (1) During monsoon, plume-like sediment dispersion seaward is observed especially in the mouths of rivers. (2) As the monsoon progresses, there is northerly transport of sediments with anticlockwise pattern within the plumes. (3) During NE monsoon, sediment concentration is less and its transport is southward. (4) During premonsoon, SS concentration is high in the near-shore water and transport is landward. Sequential OCM data analyses indicated the influence of tidal currents, especially during premonsoon in the vicinity of the river mouths on sediments dispersion. During rising tide, sediments move into the estuary, and during falling tide they flow seaward resulting in erosion and formation of shoals. Sediment-dispersal patterns largely follow wind and wave patterns, a characteristic feature of the mesotidal coast. Presence of a number of mudflats within the estuary along with the siltation in the channels suggests that a net landward transport of sediments occur in the region. [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]

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]

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]

The water depth, flow velocity, salinity, and suspended sediment concentration on an intertidal mudflat in the vicinity of a river mouth were measured for 564 wet cycles from July 2004 to October 2005. The measured time series were analyzed using time averaging to extract the wave components as well as tidal phase averaging to obtain typical variations and variability during the wet cycles. The wave component varied little during the wet cycle and was significant in the measured velocities. The variability of the time-averaged quantities for the 564 wet cycles was considerable, but the deviations from the phase-averaged values were correlated very little. As a result, the phase-averaged water fluxes and suspended sediment fluxes were approximately the same as those estimated using the phase-averaged water depth, velocities, and concentration. The phase-averaged quantities were used to understand the temporal variations of the flow and sediment transport during one typical wet cycle, which appeared to be influenced by the local bathymetry and the river discharge. [ABSTRACT FROM AUTHOR]

Vu, X.H. and Lee, J.L., 2021. Simulation study of scarp and berm formation using a suspended sediment transport model. 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. 504–508. Coconut Creek (Florida), ISSN 0749-0208. Beach berms and scarps are common morphological features that develop repetitively due to the cyclic incidence of mild and storm waves. However, beach scarp and berm formations, as well as their morphodynamics, have not been researched thoroughly. In particular, scarp generation is often observed at nourished beaches or under the incidence of oblique storm waves; scarps can pose severe risks to beach users and negatively impact local ecosystems. A numerical study was conducted using a suspended sediment transport model developed in a previous study to quantify the morphodynamic responses of beach berms and scarps to the foreshore region as well as offshore sand motion. In the present study, the destructive beach slope at the foreshore was controlled using Kim's empirical formula on the foreshore slope. [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]

Swash zone sediment transport is generally measured in an Eulerian reference frame, but this approach tends to give insufficient information on spatial transport characteristics. This paper utilizes a novel technique to map measured suspended sediment concentrations (SSC) onto the x-t plane, thus providing a visualization of SSC at all locations throughout a swash cycle. The widely adopted energetics or bed shear stress approaches to modeling suspended sediment transport in the swash predict that SSC varies directly with the horizontal velocity, u, to the power of either 2 or 3. A calibrated ballistic swash model was used to predict SSC(x,t) ∞ u² and SSC(x,t) ∞ u³. The qualitative comparison between field measurements and transport model predictions in x-t space provides the opportunity to examine the transport model performance throughout the swash zone. The agreement between observed and modeled SSC patterns was generally poor. Similar to previous observations, SSC was larger during the uprush than the backwash. During the uprush, however, the models predict a maximum in SSC at the moving shoreline and a rapid drop-off behind the leading swash edge, whereas observed SSC was maintained at high levels for most of the uprush phase. During backwash, there was very little correspondence at all between the patterns of predicted and observed SSC; in particular, observed SSC was unexpectedly small in the mid- and late stages of the backwash. A general consensus is emerging that existing swash zone sediment transport models that assume SSC is in equilibrium with the horizontal flow velocity are inadequate. This study suggests that this is probably due to presuspended sediment being advected into the swash zone, the effects of bore-generated turbulence being advected into the swash zone, and both bed shear stress and Reynolds stresses being out of phase with the horizontal flow velocity. [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]

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]

Measurements of cross-shore velocity (u) at z = 3 cm and suspended sediment concentration (SSC) at z = 1–33 cm were collected from the swash zones of gently sloping (Perranporth, UK) and steep (Sennen, UK) beaches, during morphodynamic conditions ranging from highly dissipative to almost reflective and breaker heights ranging from 0.8 to 2.2 m. Nine swash-zone data collection runs were used to compare the performance of simplified versions of Bagnold-type energetics sediment transport models on the two different beaches. Models originally designed for suspended load, where the sediment transport (I) is approximately proportional to u4, showed no apparent improvement over those intended for bedload, where I ∞ u³. It is suggested that the lowest SSC sensors could be measuring high concentrations in the sheet-flow layer, where previous laboratory results suggest a u³ model is most appropriate. The overall performance of the model is better (average r² = 76%) on the gently sloping beach than on the steep beach (average r² = 49%). Modifications to account for processes, such as bore turbulence, may improve the model's performance, particularly on steep reflective beaches. [ABSTRACT FROM AUTHOR]

Two-dimensional data of mean and sediment flow collected at a natural confluence of channels in the inner Bahía Blanca Estuary are presented. We describe the two-dimensional flow field to assess the role of changes in bed morphology occurring during transport-effective events on the structure of flow at a confluence; and to examine how the flow structure varies with changes in the ratio of momentum flux. At each station, vertical profiles of velocity, salinity, temperature and suspended sediment were obtained during the whole tidal cycle and residual fluxes were obtained. Lagrangean flux is higher than possible fresh water input, denoting an extra output of water which is the flux over the tidal flats along the southern and northern coasts of the channel. The effect of the junction produces a distortion of the vertical profile flow and in the suspended sediment transport. The effect of the particular conformation of the system makes necessary for consider the lateral effect of the tidal fiats in the circulation of the estuary which exerts a significant influence. [ABSTRACT FROM AUTHOR]

Along-channel velocity, salinity, and total suspended sediment concentration profiles were measured during 15 complete neap and spring tidal cycles in the dry and rainy seasons in four cross-sections in a tropical estuary, Itamaracá, Pernambuco, Brazil. The net longitudinal fluxes of salt and sediments were decomposed into advective, tidal, and cross-sectional shear transports. The advective transport of both salt and suspended sediments were for most parts export-directed and greater than the combined river discharge, suggesting a non-steady state. The dispersive tidal transport was decomposed into four separate mechanisms of which tidal pumping transport and tidal wave transport (similar to transport by Stokes' drift) are the main transport mechanisms. The cross-sectional shear transport was negligibly small, and thus, vertical nor lateral effects are significant with respect to longitudinal dispersion in the case of Itamaracá. [ABSTRACT FROM AUTHOR]

On a high-energy coast, with heterogeneous nearshore bathymetry and sediment dynamic (New Plymouth, New Zealand), two colours of artificial fluorescent tracer were used to i) investigate tbe sediment entrapment/bypassing of a port entrance, and ii) to monitor sediment movement from an experimental nearshore dredged-sand dump mound (47,000 m3). Two simultaneous releases lone for each colour) were made in 6 to 10 m water depths, near the port entrance and on the dump mound. 1400 m apart. Tbe tracer was tracked over 10 months by collecting and analysing 1179 surficial sediment samples, with concomitant wave/current recording at up to 13 nearshore sites. Tbe results demonstrate trapping in the breakwater tip-shoal of tbe part, by-passing and movement through the complex nearshore reef system. The dominant transport was alongshore. Tracer released near the port entrance depicted a natural sediment "pathway" past the harbour shipping entrance and over tbe rocky reefs to the beaches 4.5 km away. Very little tracer was detected within tbe harbour, indicating that tbe main transport from the release depths 16-10 ml by-passed tbe harbour entrance and tip-shoal. The tracer shows that only sediments very close to tbe harbour breakwater (i.e. within 100 m) are trapped at the harbour entrance. From the dump mound, tracer was observed to migrate mostly longshore away from tbe port, although a minor "updrift" migration was observed. The tracer results are in accordance with measured and numerically modeled currents, which show a dominant longshore flow away from the port and weak reversing flows in the quiescent lee of the harbour at the dump mound. The tracer data also suggest that the raised shore normal reefs do not present a significant impediment to longshore transport, but rather that the nearshore circulation patterns are the predominant influence on the .sediment transport vectors. Rates of tracer spreading were found to range from 0.095 to 0.288 m2s-1. which is consistent with a high-energy coastal environment. Diffusion and advection of suspended sediments is the primary mechanism of sediment transport, and tracer was found on beaches 4.5 km distant from the release point within 13 days of injection. [ABSTRACT FROM AUTHOR]

In this paper, the geometric characteristics of wave-induced offshore bars are investigated by using physical models. Both regular and irregular waves were used during the testing. Beach sand with a mean diameter of 0 35 mm and a specific gravity of 2.63 was selected for the study. The initial slope of the beach was 1:5. Different wave groups were generated over the initially flat beach, and a number of geometric parameters were determined. These parameters included the location of the bar crest, the equilibrium point, and the closure point. The results of the experimental study wore evaluated and some empirical expressions based upon the results are suggested to define those geometric parameters for pure regular waves, pure irregular waves and regular-irregular waves. The proposed formulas were compared with those of Silvester and Hsu (1997). These comparisons showed that a good correlation exists between the results of their earlier formulas and those of the proposed formulas derived for regular waves. It was also determined that the effect of wave types upon the bar crest is more than that of the equilibrium point. [ABSTRACT FROM AUTHOR]