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1.
Sediment flux in marsh tidal creeks is commonly used to gauge sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended‐sediment concentration (SSC), velocity and depth were measured near the mouths of two tidal creeks during three 6‐ to 10‐week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally averaged suspended‐sediment flux (SSF) in the tidal creeks varied from slightly landward to strongly bayward with increasing tidal energy. SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF for each deployment. During ebb tides following the highest tides, velocities exceeded 1 m s?1 in the narrow tidal creeks, resulting in negative tidally averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally averaged SSF was positive in wavy conditions with moderate tides. Spring tide sediment export at the creek mouth was about twice that at a station 130 m further up the tidal creek. The negative tidally averaged water flux near the creek mouth during spring tides indicates that in the lower marsh some of the water flooding directly across the bay–marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

2.
Suspended sediment concentration (SSC) plays an important role in the estuarine environment.Its spatial or temporal variations in coastal zones and estuaries indicate that sediments are suspended,trans...  相似文献   

3.
This paper provides a detailed study on the sedimentation patterns and the recent morphodynamic evolution affecting the macro-tidal salt marshes located west of the Mont-Saint-Michel (France). Twenty-two stations along three transects on the marshes were seasonally monitored for marsh surface level variations from 1999 to 2005, using a sediment erosion bar. The corresponding erosion/accretion rates were obtained together with data on topography, vegetation cover, and grain size of surface sediment. To examine the mechanisms contributing to the salt marsh sedimentation, the data and their evolution were treated with respect to tides, relative mean regional sea level, and wind speed/frequency variations.From 1999 to 2005, the marsh was globally accreting (from 3.45 to 38.11 mm yr−1 in the low marsh, up to 4.91 mm yr−1 in the middle marsh, and up to 1.35 mm yr−1 in the high marsh), while the study was conducted during a window of decreasing trend in mean regional sea level (−2.45 mm yr−1 according to regional-averaged time series). These sedimentation rates are one of the highest recorded worldwide; however, the sedimentation was not found to be continuous over the period in question. This pattern is illustrated by the strong extension of the marshes from 1999 to 2002, and the relative stability observed from 2003 to 2005. The imported and reworked sediments are trapped and fixed by the dense vegetation (Puccinellia maritima, Halimione portulacoides), inducing the general seaward extension of the marshes. The processes governing sediment budget (accretion/erosion) show annual, seasonal, and spatial variability on the marsh. Spatial variations display contrasted patterns of erosion/sedimentation between the low, middle, and high marsh, and between the different transects. These patterns are a result of distance from sediment sources, strong heterogeneity in vegetation cover (human induced or not), and contrasting topographic and micro-topographic characteristics. The higher accretion rates are observed in distal settings in the low marsh, and strongly decrease toward the middle and high marsh. This evolution results from a decrease in accommodation space/water column thickness, and frequency of inundation coupled with an increase in station elevation, but also from the cumulated effects of vegetation cover and micro-topography. The vegetation cover of the low and middle marsh enhance the settling and fixing of fine sediments imported through tides or dispersed by flood and ebb currents.The seasonal evolution of the marshes is marked by contrasting effects of water storage in the sediment. The overall seasonal sediment budget is controlled by the variation of the frequency of inundation relative to tidal range and marshes topography. Autumns are influenced by the tide (equinoxes), relative mean regional sea level, and variations in wind speed/frequency. Winter wind speed and frequency in relation with tidal variations appear to be the main parameters regulating winter marsh evolution. Summers are predominantly under the influence of local variations in water storage (desiccation) while external parameters generally display a low influence. Although it is not governed by any one parameter, springtime sediment budget seems to result from strong interaction between the above-cited parameters, despite the significant frequency of inundation (equinoxes).  相似文献   

4.
Organized spatial distribution of plants (plant zonation) in salt marshes has been linked to the soil aeration condition in the rhizosphere through simplistic tidal inundation parameters. Here, a soil saturation index (ratio of saturation period to tidal period at a soil depth) is introduced to describe the soil aeration condition. This new index captures the effects of not only the tidal inundation period and frequency but also the flow dynamics of groundwater in the marsh soil. One‐dimensional numerical models based on saturated flow with the Boussinesq approximations and a two‐dimensional variably saturated flow model were developed to explore the behaviour of this new soil aeration variable under the influence of spring‐neap tides. Simulations revealed two characteristic zones of soil aeration across the salt marsh: a relatively well aerated near‐creek zone and a poorly aerated interior zone. In the near‐creek zone, soils undergo periodic wetting and drying as the groundwater table fluctuates throughout the spring‐neap cycle. In the interior, the soil remains largely water saturated except for neap tide periods when limited drainage occurs. Although such a change of soil aeration condition has been observed in previous numerical simulations, the soil saturation index provides a clear delineation of the zones that are separated by an ‘inflexion point’ on the averaged index curve. The results show how the saturation index represents the effects of soil properties, tidal parameters and marsh platform elevation on marsh soil aeration. Simulations of these combined effects have not been possible with traditional tidal inundation parameters. The saturation index can be easily derived using relatively simple models based on five non‐dimensional variables. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

5.
Recent initiatives directing tidal power development in the Bay of Fundy have raised questions about far‐field environmental impacts related to energy extraction. It is understood that commercial scale tidal power installations in the Minas Passage will result in an overall decrease in tidal amplitude in the Minas Basin. Corresponding changes in sedimentation patterns may or may not be within the natural range of variability, and it is hypothesized that intertidal sedimentation rates will demonstrate a non‐linear response to modification of the tidal energy regime. This research considers acoustic Doppler velocimeter (ADV) and optical backscatter sensor (OBS) data from a sheltered tidal creek in the Minas Basin, for analysis of tidal characteristics in a hypertidal creek environment over spring and neap tidal cycles. Sediment deposition in the creek was also measured. Results show a first‐order control of topography on flow magnitude in the tidal creek, which impacts net sediment deposition through resuspension and removal of newly introduced material. This study demonstrates that tides which peak around the bankfull level show reduced early ebb stage turbulence and flow velocity and encourage an extended depositional period. The dynamics of marshfull tides may be responsible for the maximum sediment deposition in tidal creeks, providing large amounts of material that is eventually distributed to and deposited on marsh surfaces. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

6.
Modeling efforts have considerably improved our understanding on the chief processes that govern the evolution of salt marshes under climate change. Yet the spatial dynamic response of salt marshes to sea-level rise that results from the interactions between the tidal landforms of interest and the presence of bio-geomorphic features has not been addressed explicitly. Accordingly, we use a modeling framework that integrates the co-evolution of the marsh platform and the embedded tidal networks to study sea-level rise effects on spatial sediment and vegetation dynamics in microtidal salt marshes considering different ecological scenarios. The analysis unveils mechanisms that drive spatial variations in sedimentation rates in ways that increase marsh resilience to rising sea-levels. In particular, marsh survival is related to the effectiveness of transport of sediments toward the interior marshland. This study hints at additional dynamics related to the modulation of channel cross-sections affecting sediment advection in the channels and subsequent delivery in the inner marsh, which should be definitely considered in the study of marsh adaptability to sea-level rise and posterior management.  相似文献   

7.
Recent changes in the UK's coastal defence strategy have resulted in the introduction of Managed Realignment (MR), a technique which attempts to establish salt marshes on low-lying coastal farmland. This work investigates the impact of MR, in particular on the interactions between sediment movement, changes in heavy metal concentrations and salt marsh development. Pre- and post-inundation samples were collected and analysed between 1995 and 1997. Sediment transport patterns (1996) demonstrated that sediment particles were distributed by tides around the site, resulting in a change in the spatial distribution of the metals which was related to the sediment particle size distribution. Despite the presence of some metal contaminants found within the MR site, vegetated salt marsh has developed since 1997. However, heavy metals such as Cu, Mn, Ni, Pb and Zn exhibited relative depletion in the sediment developing with salt marsh in 1997, which is in agreement with data indicating that concentrations of metals within sediments is related to frequency of tidal inundation. During initial development of the site, sediment transport was the main factor controlling metal distribution, however, subsequently the frequency of tidal inundation became the most significant factor. Further work may allow for prediction of how future MR sites will develop with respect to redistribution of sediments and subsequent transport of contaminants in the dissolved phase.  相似文献   

8.
In parts of North America and Europe, present and future sedimentary deficits translate into major areal losses of coastal salt marsh. Physically based simulations of medium- to long-term adjustment to accelerated sea-level rise are few, partly due to the difficulty in extrapolating imperfectly understood sedimentation parameters. This paper outlines the implementation and application of a simple one-dimensional mass balance model designed to simulate the vertical adjustment of predominantly minerogenic marsh surfaces to various combinations of sediment supply, tidal levels and regional subsidence. Two aspects of marsh growth are examined, with reference to sites on the macro-tidal north Norfolk coast, U.K.: (i) historical marsh growth under a scenario of effective (long-term) eustatic stability but slow regional subsidence; and (ii) marsh response to various non-linear eustatic rise scenarios for the next century. In contrast to more organogenic North American marshes, sedimentation rates in Norfolk are strongly time-dependent. Where the overall sediment budget is so closely linked to marsh age and relative elevation, some form of numerical simulation offers a preferred means of predicting the impact of accelerated sea-level rise. Simulations performed here show that only the most dramatic eustatic scenarios result in ecological ‘drowning’ and reversion to tidal flat within the conventional 2100 prediction interval. Currently favoured scenarios give rise to accretionary deficits which are clearly sustainable in the short-term, albeit at the expense of increased inundation frequency and consequent changes in the distribution of marsh flora and fauna.  相似文献   

9.
Suspended sediment is the primary source for a sustainable agro‐ecosystem in the Mekong Delta by providing nutrient input for the subsequent cropping season. In addition, the suspended sediment concentration (SSC) plays an important role in the erosion and deposition processes in the Delta; that is, it influences the morphologic development and may counteract the deltaic subsidence and sea level rise. Despite this importance, little is known about the dynamics of suspended sediment in the floodplains of the Mekong Delta. In particular, quantitative analyses are lacking mainly because of data scarcity with respect to the inundation processes in the floodplains. In 2008, therefore, a comprehensive in situ system to monitor the dynamics of suspended sediment in a study area located in the Plain of Reeds was established, aiming at the characterization and quantification of suspended sediment dynamics in the deeply inundated parts of the Vietnamese part of the Mekong Delta. The monitoring system was equipped with seven water quality–monitoring stations. They have a robust design and autonomous power supply suitable for operation on inundated floodplains, enabling the collection of reliable data over a long period of time with a high temporal resolution. The data analysis shows that the general seasonal dynamics of suspended sediment transport in the Delta is controlled by two main mechanisms: the flood wave of the Mekong River and the tidal backwater influences from the coast. In the channel network, SSC decreases exponentially with distance from the Mekong River. The anthropogenic influence on SSC could also be identified for two periods: at the start of the floodplain inundation and at the end of the flood period, when subsequent paddy rice crops are prepared. Based on the results, we recommend an operation scheme for the sluice gates, which intends to distribute the sediment and thus the nutrients equally over the floodplain. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

10.
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11.
Mainstem–floodplain material exchange in the tidal freshwater reach of major rivers may lead to significant sequestration of riverine sediment, but this zone remains understudied compared to adjacent fluvial and marine environments. This knowledge gap prompts investigation of floodplain-incising tidal channels found along the banks of tidal rivers and their role in facilitating water and suspended-sediment fluxes between mainstem and floodplain. To evaluate this role, and how it evolves along the tidal river and with time, we measured water level, flow velocity, temperature, and suspended-sediment concentration (SSC) in four tidal channels along the tidal Amazon River, Brazil. Eleven deployments were made during low, rising, high, and falling seasonal Amazon discharge. Generally, channels export high-SSC water from the mainstem to the tidal floodplain on flood tides and transfer low-SSC water back to the mainstem on ebbs. Along the length of the tidal river, the interaction between tidal and seasonal water-level variations and channel–floodplain morphology is a primary control on tidal-channel sediment dynamics. Close to the river mouth, where tides are large, this interaction produces transient flow features and current-induced sediment resuspension, but the importance of these processes decreases with distance upstream. Although the magnitude of the exchange of water and sediment between mainstem and floodplain via tidal channels is a small percentage of the total mainstem discharge in this large tidal-river system, tidal channels are important conduits for material flux between these two environments. This flux is critical to resisting floodplain submergence during times of rising sea level. © 2019 John Wiley & Sons, Ltd.  相似文献   

12.
This paper presents results of investigations (1983–1992) into rates of change, morphology and processes occurring during the current erosional phase in a Morecambe Bay cyclic saltmarsh, in which it has narrowed from c. 1000 m (1975) to c. 150 m (1992). Monthly monitoring of marsh edge erosion and creek knickpoint retreat has revealed temporal and spatial variations. Highest frequency changes of low magnitude coincided with non-storm conditions and overmarsh tides above 5·80 m OD, which submerged the whole marsh. Less frequent changes of greater magnitude were associated with both overmarsh tides and strong onshore winds over 15 ms?1, which generated high energy waves. The lowest frequency change of greatest magnitude occurred during an extreme onshore storm event and surge. Morphologically, during the erosional phase, a low angled landward slope was generated as erosion of the c. 0·5 m high active seaward cliff coincided with vertical accretion of 0·07 ma?1 of relatively coarse sediment on the marsh surface immediately landward. Tidal hydrodynamics strongly influence the saltmarsh, which is confined to the upper 2·5 m of the macrotidal range (maximum c. 10·5 m). During overmarsh spring tides (maximum creek flood flow rate 0·13 ms?1, up to bankfull level), flooding begins over lower landward creek banks before submerging the higher marsh edge. During ebb tides, water trapped by this higher edge can escape seaward only via the creeks (maximum ebb velocities 2·07 ms?1 below bankfull level). Wave erosion also is limited to spring tides. Monthly mapping of the Kent Estuary channel pattern seaward of the saltmarsh showed that medium term higher erosion rates were related to the presence of a large channel, which lowered the adjacent creek base level and allowed larger waves to attack the marsh edge than when a sandbank flanked the marsh. Major River Kent channel shifts appear to initiate accretional or erosional phases of cyclic saltmarsh development.  相似文献   

13.
Digital elevation models (DEMs) were compared to characterize how well airborne lidar (light detection and ranging) data depict the microtopography of a salt marsh. 72,000 GPS points and 700,000 lidar points from a 1 km2 salt marsh island were linearly interpolated using identical DEM configurations. Overall, 78% of lidar elevations were within ±0.15 m of the high precision GPS elevations. Spatial arrangement of difference values reveal that lidar performed best on the marsh platform, and poorly along tidal creeks and creek heads. Also, the overall shape of the salt marsh was poorly defined, even where lidar data were within the reported range of accuracy. These observations indicate that lidar appears to be a robust tool for mapping intertidal landscapes. However, lidar DEMs may not adequately resolve the microtopographic variations of a salt marsh, and for research questions that require accurate depiction of small‐scale tidal creek networks and subtle terrain features lidar data should be augmented with other information. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

14.
Salt marshes are ubiquitous features of the tidal landscape governed by mutual feedbacks among processes of physical and biological nature. Improving our understanding of these feedbacks and of their effects on tidal geomorphological and ecological dynamics is a critical step to address issues related to salt-marsh conservation and response to changes in the environmental forcing. In particular, the spatial variation of organic and inorganic soil production processes at the marsh scale, a key piece of information to understand marsh responses to a changing climate, remains virtually unexplored. In order to characterize the relative importance of organic vs. inorganic deposition as a function of space, we collected 33 shallow soil sediment samples along three transects in the San Felice and Rigà salt marshes located in the Venice lagoon, Italy. The amount of organic matter in each sample was evaluated using Loss On Ignition (LOI), a hydrogen peroxide (H2O2) treatment, and a sodium hypochlorite (NaClO) treatment following the H2O2 treatment. The grain size distribution of the inorganic fraction was determined using laser diffraction techniques. Our study marshes exhibit a weakly concave-up profile, with maximum elevations and coarser inorganic grains along their edges. The amount of organic and inorganic matter content in the samples varies with the distance from the marsh edge and is very sensitive to the specific analysis method adopted. The use of a H2O2+NaClO treatment yields an organic matter density value which is more than double the value obtained from LOI. Overall, inorganic contributions to soil formation are greatest near the marsh edges, whereas organic soil production is the main contributor to soil accretion in the inner marsh. We interpret this pattern by considering that while plant biomass productivity is generally lower in the inner part of the marsh, organic soil decomposition rates are highest in the better aerated edge soils. Hence the higher inorganic soil content near the edge is due to the preferential deposition of inorganic sediment from the adjacent creek, and to the rapid decomposition of the relatively large biomass production. The higher organic matter content in the inner part of the marsh results from the small amounts of suspended sediment that makes it to the inner marsh, and to the low decomposition rate which more than compensates for the lower biomass productivity in the low-lying inner zones. Finally, the average soil organic carbon density from the LOI measurements is estimated to be 0.044 g C cm−3. The corresponding average carbon accumulation rate for the San Felice and Rigà salt marshes, 132 g C m−2 yr−1, highlights the considerable carbon stock and sequestration rate associated with coastal salt marshes.  相似文献   

15.
The geomorphology of the southern Yellow Sea（SYS） is characterized by offshore radial sand ridges（RSR）.An offshore tidal channel（KSY Channel） is located perpendicular to the coast,comprised of a main and a tributary channel separated by a submarine sand ridge（KSY Sand Ridge） extending seaward.In order to investigate the interactions among water flow,sediment transport,and topography,current velocity and suspended sediment concentration（SSC） were observed at 11 anchor stations along KSY Channel in RSR during a spring tide cycle.High resolution bottom topography was also surveyed.Residual currents and tidally averaged suspended sediment fluxes were calculated and analyzed by using the decomposition method.Results suggested that the water currents became stronger landward but with asymmetrical current speed and temporal duration of flood and ebb tides.Residual currents showed landward water transport in the nearshore channel and a clockwise circulation around the KSY Sand Ridge.Tidally-averaged SSC also increased landward along the channel.The main mechanisms controlling SSC variations were resuspension and horizontal advection,with spatial and temporal variations in the channel,which also contributed to sediment redistribution between channels and sand ridges.Residual flow transport and the tidal pumping effect dominated the suspended sediment flux in the KSY Channel.The KSY Sand Ridge had a potential southward migration due to the interaction between water flow,sediment transport,and topography.  相似文献   

16.
An experimental study of temperature cycles and the heat budget in the Duplin River, a tidal creek bordered by extensive intertidal salt marshes, was carried out in late summer of 2003 and spring of 2004 near Sapelo Island on the central Georgia coast in the southeastern US. Three water masses are identified with differing temperature and salinity regimes, the characteristics of which are dictated by channel morphology, tidal communication with the neighboring sound, ground water hydrology, the extent of local intertidal salt marshes and side channels and the spring–neap tidal cycle (which controls both energetic mixing and, presumably, ground water input). For the first experiment, heat budgets are constructed for the upper (warmer) and lower (cooler) areas of the Duplin River showing the diminishing importance of tidal advection away from the mouth of the creek along with the concomitant increase in the importance of both direct atmospheric fluxes and of interactions with the marsh and side creeks. The second experiment, in the spring of 2004, reexamines the heat budget on seasonal and daily averaged scales revealing the decreased importance of advective fluxes relative to direct atmospheric fluxes on this scale but the constant importance of marsh/creek interactions regardless of time scale or season. Short period temperature fluctuations which affect larval development are examined and analogies are drawn to use heat to understand the marsh as a source of sediment, carbon and other nutrients.  相似文献   

17.
Few hyperpycnal flows have ever been observed in marine environments although they are believed to play a critical role in sediment dispersal within estuarine and deltaic depositional systems. The paper describes hyperpycnal flows observed in situ off the Huanghe (Yellow River) mouth, their relationship to tidal cycles, and the mechanisms that drive them. Simultaneous observations at six mooring stations during a cruise off the Huanghe mouth in the flood season of 1995 suggest that hyperpycnal flows observed at the river mouth are initiated by high concentrations of sediment input from river and modulated by tides. Hyperpycnal flows started near the end of ebb tides, when near‐bottom suspended sediment concentration (SSC) increased rapidly and salinity decreased drastically (an inverse salt wedge). The median grain size of suspended particles within the hyperpycnal layer increased, causing strong stratification of the suspended sediments in the water column. Towards the end of flood tides, the hyperpycnal flow attenuated due to frictions at the upper and lower boundaries of the flow and tidal mixing, which collapsed the stratification of the water column. Both sediment concentration and median grain size of suspended particles within the bottom layer significantly decreased. The coarser sediment particles were deposited and the hyperpycnal flows stopped. The intra‐tidal behaviors of hyperpycnal flows are closely associated with the variations of SSC, salinity, and stratification of the water column. As nearly 90% of riverine sediment is delivered to the sea during the flood seasons when hyperpycnal flows are active, hyperpycnal flows at the Huanghe mouth and the river's high sediment loads have caused rapid accretion of the Huanghe delta. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

18.
Vegetation plays a critical role in modifying inundation and flow patterns in salt marshes. In this study, the effects of vegetation are derived and implemented in a high‐resolution, subgrid model recently developed for simulating salt marsh hydrodynamics. Vegetation‐induced drag forces are taken into account as momentum sink terms. The model is then applied to simulate the flooding and draining processes in a meso‐tidal salt marsh, both with and without vegetation effects. Marsh inundation and flow patterns are significantly changed with the presence of vegetation. A smaller area of inundation occurs when vegetation is considered. Tides propagate both on the platform and through the channels when vegetation is absent, whereas flows concentrate mainly in channels when vegetation is present. Local inundation on vegetated platforms is caused mainly by water flux spilled from nearby channels, with a flow direction perpendicular to the channel edges, whereas inundation on bare platforms has contributions from both local spilled‐over water flux and remote advection from adjacent platforms. The flooding characteristics predicted by the model showed a significant difference between higher marsh and lower marsh, which is consistent with the wetlands classification by the National Wetlands Inventory (NWI). The flooding characteristics and spatial distribution of hydroperiod are also highly correlated with the vegetation zonation patterns observed in Google Earth imagery. Regarding the strong interaction between flow, vegetation and geomorphology, the conclusion highlights the importance of including vegetation in the modeling of salt marsh dynamics. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

19.
This paper uses numerical simulation of flood inundation based on a coupled one‐dimensional–two‐dimensional treatment to explore the impacts upon flood extent of both long‐term climate changes, predicted to the 2050s and 2080s, and short‐term river channel changes in response to sediment delivery, for a temperate upland gravel‐bed river. Results show that 16 months of measured in‐channel sedimentation in an upland gravel‐bed river cause about half of the increase in inundation extent that was simulated to arise from climate change. Consideration of the joint impacts of climate change and sedimentation emphasized the non‐linear nature of system response, and the possibly severe and synergistic effects that come from combined direct effects of climate change and sediment delivery. Such effects are likely to be exacerbated further as a result of the impacts of climate change upon coarse sediment delivery. In generic terms, these processes are commonly overlooked in flood risk mapping exercises and are likely to be important in any river system where there are high rates of sediment delivery and long‐term transfer of sediment to floodplain storage (i.e. alluviation involving active channel aggradation and migration). Similarly, attempts to reduce channel migration through river bank stabilization are likely to exacerbate this process as without bank erosion, channel capacity cannot be maintained. Finally, many flood risk mapping studies rely upon calibration based upon combining contemporary bed surveys with historical flood outlines, and this will lead to underestimation of the magnitude and frequency of floodplain inundation in an aggrading system for a flood of a given magnitude. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

20.
The potential for rapid coastline modification in the face of sea-level rise or other stressors is alarming, since coasts are often densely populated and support valuable infrastructure. In addition to coastal submergence, nutrient-related water pollution is a growing concern for coastal wetlands. Previous studies found that the Suspended Sediment Concentration (SSC) of coastal wetlands acts as a first-order control of their sustainability, but SSC dynamics are poorly understood. Our study focuses on the Virginia Coast Reserve (VCR) Long Term Ecological Research (LTER) site, a shallow multiple tidal inlet system in the USA. We apply numerical modelling (Delft3D-SWAN) and subsequent analyses to determine SSC dynamics within the VCR. In particular, we consider two important controls on SSC in the system: vegetation (seagrass and salt marsh) and offshore waves. Our results show that vegetation colonies and increased wave energy lengthen water residence time. The reduction in the tidal prism decreases SSC export from the bay via tidal inlets, leading to increased sediment retention in the bay. We found that alongshore currents can enhance lagoon SSC by importing fine sediments from an adjacent inlet along the coastline. Our numerical experiments on vegetation seasonality can improve the understanding of wave climate impact on coastal bay sediment budget. Offshore waves increase sediment export from coastal bays, particularly during winter seasons with low vegetation density. Therefore, our study can help managers and stakeholders to understand how to implement restoration strategies for the VCR. © 2020 John Wiley & Sons, Ltd.  相似文献   

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