Observational and numerical particle tracking to examine sediment dynamics in a Mississippi River delta diversion

Yuill, Brendan; Meselhe, E. A.; Marsh, Jonathan; Kolker, Alexander S.; Ameen, Alexander D.

doi:10.1016/j.ecss.2017.06.004

Cited by 21 publications

(21 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Allison et al (2017) suggested that this more even distribution could be due to influence of tides, waves, or wind-driven currents, which could influence fluid flow in the system and result in changes to the distribution of sediment deposits. However, these forces were not accounted for in the Allison et al (2017) model. While the microtidal conditions in coastal Louisiana have been shown to have little effect on Mississippi River stages at average and high discharges (Karadogan et al, 2009), it has been suggested that tides may play an important role in regulating water levels and controlling geomorphic evolution in planned sediment diversions that will carry smaller discharges (Hiatt et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Influence of Floods, Tides, and Vegetation on Sediment Retention in Wax Lake Delta, Louisiana, USA

2020

View full text Add to dashboard Cite

Sediment is the most valuable natural resource for deltaic environments because it is required to build new land. For land building to occur, sediment must be retained in the delta instead of being transported offshore. Despite this, we do not know what controls sediment retention within a delta. Here we use a calibrated numerical model of Wax Lake Delta, Louisiana, USA to analyze sediment retention for different riverine flood magnitudes, tidal amplitudes, and vegetation extents. Our results show that as riverine flood magnitude increases, areally averaged vertical accretion increases from 0.33 to 2 cm per 60-day flood, but sediment retention decreases from 72% to 34%. For the uniform vegetation characteristics considered, the buffering effect, defined as the reduction of sediment flux onto the islands in the presence of vegetation, reduces the sediment flux onto the islands 14 to 22% on a fully vegetated delta. When sediment is transported onto the islands, vegetation enhances retention, which we refer to as the trapping effect, bỹ 10%. But, this does not offset the buffering effect, and vegetation decreases vertical accretion and retention in the delta up to 6% (or~0.5 cm per 60-day flood). We suggest that vegetation will increase sedimentation only when trapping compensates for buffering. Finally, greater tidal amplitude at higher discharges enhances vertical accretion by~0.5 cm per 60-day flood compared to smaller tidal amplitudes. These results provide insight on the mechanisms behind coastal systems growth, and suggest how sediment diversions might be operated more efficiently in deltas with reduced sediment supply.

show abstract

Section: Introductionmentioning

confidence: 99%

Influence of Floods, Tides, and Vegetation on Sediment Retention in Wax Lake Delta, Louisiana, USA

2020

View full text Add to dashboard Cite

show abstract

“…Previous studies using Lagrangian particle tracking to simulate sediment transport in rivers relied on the same simplifying assumption (e.g. Shams et al ., 2002; Pasiok and Stilger‐Szydło, 2010; Allison et al ., 2017).…”

Section: Methodsmentioning

confidence: 99%

Sand settling through bedform‐generated turbulence in rivers

Yuill

Wang

Meselhe

et al. 2020

Earth Surf Processes Landf

View full text Add to dashboard Cite

Fluvial bedforms generate a turbulent wake that can impact suspended-sediment settling in the passing flow. This impact has implications for local suspended-sediment transport, bedform stability, and channel evolution; however, it is typically not well-considered in geomorphologic models. Our study uses a three-dimensional OpenFOAM hydrodynamic and particle-tracking model to investigate how turbulence generated from bedforms and the channel bed influences medium sand-sized particle settling, in terms of the distribution of suspended particles within the flow field and particle-settling velocities. The model resolved the effect of an engineered bedform, which altered the flow field in a manner similar to a natural dune. The modelling scenarios alternated bed morphology and the simulation of turbulence, using detached eddy simulation (DES), to differentiate the influence of bedform-generated turbulence relative to that of turbulence generated from the channel bed. The bedform generated a turbulent wake that was composed of eddies with significant anisotropic properties. The eddies and, to a lesser degree, turbulence arising from velocity shear at the bed substantially reduced settling velocities relative to the settling velocities predicted in the absence of turbulence. The eddies tended to advect sediment particles in their primary direction, diffuse particles throughout the flow column, and reduced settling likely due to production of a positively skewed vertical-velocity fluctuation distribution. Study results suggest that the bedform wake has a significant impact on particle-settling behaviour (up to a 50% reduction in settling velocity) at a scale capable of modulating local suspended transport rates and bedform dynamics.

show abstract

“…River deltas, like many ecosystems, are threatened in the Anthropocene (Syvitski et al, 2009). This has led to an increase in research seeking to understand how these systems function through geomorphological models (Allison et al, 2017;Edmonds & Slingerland, 2009;Meselhe et al, 2012;Nardin et al, 2016;Shaw, Mohrig, & Wagner, 2016;Tejedor et al, 2017;Wang et al, 2014), and the findings of these studies are being incorporated into strategies to protect deltas like that for the Mississippi River Delta (CPRA, 2017;Kolker et al, 2018). Many of these models include sediment particle size and topography (Burpee et al, 2015;Edmonds & Slingerland, 2009).…”

Section: Connecting Om Dynamics With Environmental Driversmentioning

confidence: 99%

Factors Controlling Storage, Sources, and Diagenetic State of Organic Carbon in a Prograding Subaerial Delta: Wax Lake Delta, Louisiana

et al. 2019

Self Cite

View full text Add to dashboard Cite

Wax Lake Delta, southern Louisiana, is a coastal delta that formed following the dredging of a river channel in 1941 and is a field model for investigating the geomorphology, ecology, carbon dynamics, and carbon storage capacity in young prograding deltas. However, it is unknown how the transition from subaqueous to subaerial sediments affects the sources and quality of the sequestered carbon. We investigated these variations within the sediments of Wax Lake Delta using amino acid, lignin, and stable carbon isotope compositions of the organic matter (OM). A principal component analysis of these proxies highlighted variability in organic carbon (OC) composition with changes in elevation. The transition from subaqueous to subaerial sediments at 0‐cm mean lower low water is an important component of the OM composition. In addition to the changes observed for OM source and quality, the OC loadings (OC/SA; mg C/m2) also increase as the delta aggrades and accumulates sediments with loadings typical of delta topsets and mobile mud banks (OC/SA < 0.4) to riverine sediments (0.5 < OC/SA < 1) and eventually to highly productive regions (OC/SA > 1). Linking this multiproxy approach with environmental variables such as elevation provides a path for incorporating OM dynamics into geomorphic models.

show abstract

Observational and numerical particle tracking to examine sediment dynamics in a Mississippi River delta diversion

Cited by 21 publications

References 33 publications

Influence of Floods, Tides, and Vegetation on Sediment Retention in Wax Lake Delta, Louisiana, USA

Influence of Floods, Tides, and Vegetation on Sediment Retention in Wax Lake Delta, Louisiana, USA

Sand settling through bedform‐generated turbulence in rivers

Factors Controlling Storage, Sources, and Diagenetic State of Organic Carbon in a Prograding Subaerial Delta: Wax Lake Delta, Louisiana

Contact Info

Product

Resources

About