Sediment Trapping and Transport in the ACE Basin, South Carolina

Blake, A. C.; Kineke, Gail C.; Milligan, Timothy G.; Alexander, Clark

doi:10.2307/1352880

Cited by 21 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This phenomenon was investigated and proved numerically by Geyer (1993) and Burchard and Baumert (1998). Blake et al (2001) observed the same behaviour in the ACE Basin.…”

Section: Impact Of Density Gradients On Turbidity Maximum Characterismentioning

confidence: 54%

Formation and structure of the turbidity maximum in the macrotidal Charente estuary (France): Influence of fluvial and tidal forcing

Toublanc

Brenon

Coulombier

2016

Estuarine, Coastal and Shelf Science

View full text Add to dashboard Cite

a b s t r a c tUnderstanding estuarine sediment dynamics and particularly turbidity maximum dynamics is crucial for the management of these coastal systems. Various processes impact the formation, movement and structure of the turbidity maximum. Several studies have shown that tidal asymmetry and density gradients are responsible for the presence of this suspended sedimentary mass.The Charente estuary is a highly turbid system (with suspended sediment concentrations often in excess of 5 g/L) that remains poorly understood despite its strong impact on local activities. In this study, a three-dimensional hydrosedimentary model is developed to represent the sediment dynamics of this estuary. Model validation demonstrates good accuracy, especially on reproducing semi-diurnal and spring-neap variability. Several simulations are performed to evaluate the influence of tides and river discharge on the turbidity maximum. Mean and maximum suspended sediment concentrations (SSC) and sediment stratification are calculated. SSC transects are also used to visualize the suspended sediment distribution along the estuary.The turbidity maximum generally oscillates between the river mouth and the Rochefort area (20 e30 km upstream). The model shows strong variations at different time scales, and demonstrates that SSC is mainly driven by deposition/resuspension processes. Spring-neap comparisons show that the turbidity maximum is not well-defined during neap tides for low and mean runoff conditions. Simulations of spring tides and/or high runoff conditions all result in a compact suspended sedimentary mass.Performing simulations without taking density gradients into account demonstrates that tidal asymmetry is the main mechanism leading to the formation of the turbidity maximum. However, density gradients contribute to maintaining the stability of the turbidity maximum. Vertical stratification traps sediments at the bottom. Longitudinal stratification ensures a sharper edge at the downstream limit of the suspended sedimentary mass, preventing a massive export of sediments.

show abstract

“…This phenomenon was investigated and proved numerically by Geyer (1993) and Burchard and Baumert (1998). Blake et al (2001) observed the same behaviour in the ACE Basin.…”

Section: Impact Of Density Gradients On Turbidity Maximum Characterismentioning

confidence: 54%

Formation and structure of the turbidity maximum in the macrotidal Charente estuary (France): Influence of fluvial and tidal forcing

Toublanc

Brenon

Coulombier

2016

Estuarine, Coastal and Shelf Science

View full text Add to dashboard Cite

show abstract

“…ETM are typically created by interactions between river flow and tidal forcing and are located at the boundary of the salt wedge (i.e., approximately station 3) (38). They are characterized as regions where there are elevated concentrations of flocculent material and suspended solids (7,44). Our findings that the TSS content was substantially higher and the ratio of OS content to TSS content was lower in the ACE Basin estuary (Table 2) than in the NI estuary suggested that flocculent material and/or riverine debris, and not microbially derived debris, was primarily responsible for most of the observed turbidity in the ACE Basin estuary.…”

Section: Discussionmentioning

confidence: 69%

Contrasting Patterns of Phytoplankton Community Pigment Composition in Two Salt Marsh Estuaries in Southeastern United States

Noble

Tymowski²,

Fletcher

et al. 2003

Appl Environ Microbiol

View full text Add to dashboard Cite

Phytoplankton community pigment composition and water quality were measured seasonally along salinity gradients in two minimally urbanized salt marsh estuaries in South Carolina in order to examine their spatial and temporal distributions. The North Inlet estuary has a relatively small watershed with minimal fresh water input, while the Ashepoo, Combahee, and Edisto (ACE) Basin is characterized by a relatively greater influence of riverine drainage. Sampling stations were located in regions of the estuaries experiencing frequent diurnal tidal mixing and had similar salinity and temperature regimens. Phytoplankton community pigment composition was assessed by using high-performance liquid chromatography (HPLC) and multivariate statistical analyses. Shannon diversity index, principal-component, and cluster analyses revealed that phytoplankton community pigments in both estuaries were seasonally variable, with similar diversities but different compositions. The temporal pigment patterns indicated that there was a relatively weak correlation between the pigments in ACE Basin and the relative persistence of photopigment groups in North Inlet. The differences were presumably a consequence of the unpredictability and relatively greater influence of river discharge in the ACE Basin, in contrast to the greater environmental predictability of the more tidally influenced North Inlet. Furthermore, the timing, magnitude, and pigment composition of the annual phytoplankton bloom were different in the two estuaries. The bloom properties in North Inlet reflected the predominance of autochthonous ecological control (e.g., regenerated nutrients, grazing), and those in ACE Basin suggested that there was greater influence of allochthonous environmental factors (e.g., nutrient loading, changes in turbidity). These interestuarine differences in phytoplankton community structure and control provide insight into the organization of phytoplankton in estuaries.Processes and mechanisms that determine the spatial and temporal patterns of phytoplankton have been a central focus of marine research for decades. This research has led to the identification of biotic and abiotic factors that regulate primary productivity and the development of models that describe phytoplankton growth dynamics under specific environmental conditions (4). Phytoplankton communities are multispecies communities which are highly complex in terms of their diversity and dynamics. Successional shifts in phytoplankton community structure are primarily due to changes in environmental variables (e.g., degree or type of nutrient limitation) and/or shifts in higher trophic levels (e.g., micro-versus mesozooplankton) (23,35,40,54,56). How phytoplankton community composition changes with environmental variables and/or preferential grazing by herbivores is not well understood, particularly in estuarine ecosystems. Identifying the ecological variables that regulate phytoplankton community structure is essential for facilitating the development of broad hypotheses underlying our...

show abstract

“…Field data collected in partially mixed and wellmixed estuaries reveal the presence of pronounced local maxima in SSC, when moving in both the longitudinal direction (Kappenberg and Grabemann 2001;Blake et al 2001;Lin and Kuo 2001;North et al 2004; Uncles et al 2006) and the lateral direction (Nichols 1972;Geyer et al 1998;Fugate et al 2007). Various models have been developed to explain the entrapment of sediments in specific areas.…”

Section: Introductionmentioning

confidence: 99%

Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

2009

View full text Add to dashboard Cite

A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom profile. For a deep, well-mixed, tidally dominated channel, partial slip decreases the relative importance of Coriolis deflection on the generation of cross-channel flow patterns. This has profound implications for the lateral distribution of residual salinity that drives the cross-channel residual circulation pattern. Transverse sediment transport, however, is always found to be governed by a balance between advection of residual sediment concentration by residual lateral flow on the one hand and cross-channel diffusion on the other hand. Hence, the changes in the cross-channel distribution of residual salinity modify the lateral sediment distribution. For no slip, a single turbidity maximum occurs. In contrast, partial slip gives a gradual transition to a symmetrical density distribution with a turbidity maximum near each bank. For a more shallow, partially mixed tidal channel that represents the James River, a single turbidity maximum at the left bank is found irrespective of the near-bed slip condition. In this case, semi-diurnal contributions to sediment distribution and lateral flow play an important role in cross-channel sediment transport. As vertical viscosity and diffusivity are increased, a second maximum at the right bank again exists for partial slip.

show abstract

Sediment Trapping and Transport in the ACE Basin, South Carolina

Cited by 21 publications

References 25 publications

Formation and structure of the turbidity maximum in the macrotidal Charente estuary (France): Influence of fluvial and tidal forcing

Formation and structure of the turbidity maximum in the macrotidal Charente estuary (France): Influence of fluvial and tidal forcing

Contrasting Patterns of Phytoplankton Community Pigment Composition in Two Salt Marsh Estuaries in Southeastern United States

Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

Contact Info

Product

Resources

About