Implications of Texture and Erodibility for Sediment Retention in Receiving Basins of Coastal Louisiana Diversions

Xu, Kehui; Bentley, Samuel J.; Robichaux, Patrick; Sha, Xiaoyu; Yang, Hua-Qian

doi:10.3390/w8010026

Cited by 54 publications

(15 citation statements)

References 41 publications

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“…Through filtration of collected turbidity solutions, we measured the eroded mass for each imposed shear stress, which is used to generate eroded mass curves for each experimental sediment mixture. More methodological details can be found in Xu et al ().…”

Section: Methodsmentioning

confidence: 99%

Influence of Sediment Cohesion on Deltaic Morphodynamics and Stratigraphy Over Basin‐Filling Time Scales

Benson

Harlan

et al. 2017

JGR Earth Surface

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Results from physical and numerical experiments suggest that sediment cohesion influences deltaic morphodynamics by promoting the development and maintenance of channels. As a result, cohesion is thought to increase the magnitude and time scales of internally generated (autogenic) processes and the dimensions of their stratigraphic products. We test these hypotheses by examining the surface processes and stratigraphic products from a suite of physical experiments where the influence of cohesion is isolated over temporal and spatial scales important for basin filling. Given the stochastic nature of autogenic sediment transport processes, we develop and employ a range of statistical tools and metrics. We observe that (1) an increase in sediment cohesion decreases lateral channel mobility and thus increases the time necessary to regrade deltaic surfaces; (2) enhanced channelization, due to sediment cohesion, increases the time necessary for the deposits of autogenic processes to average together and produce stratigraphic products with shapes set by the generation of regional accommodation; (3) cohesion promotes the transport of suspended sediment to terrestrial overbank and marine environments, which decreases the volume of channel, relative to overbank and marine deposits in the stratigraphic record. This increase in overbank and marine deposition changes the spatial distribution of sand in stratigraphy, with higher cohesion linked to enhanced segregation of fine particles from coarse sand in the experimental deposits. Combined, these results illustrate how the cohesion of sediment is fundamental in setting autogenic spatial and temporal scales and needs to be considered when inverting stratigraphic architecture for paleo‐environmental history.

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Section: Methodsmentioning

confidence: 99%

Influence of Sediment Cohesion on Deltaic Morphodynamics and Stratigraphy Over Basin‐Filling Time Scales

Benson

Harlan

et al. 2017

JGR Earth Surface

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“…Low trapping efficiencies of 0.10-0.20 have been reported by Syvitski et al (2009) for small, steep-gradient rivers and efficiencies of 0.50-0.60 for larger deltas with multiple distributary channels. Multiple studies on sediment retention have reported sediment trapping efficiencies between 0.27 and nearly 1.0 for Mississippi and Atchafalaya diversion systems (Xu et al 2016), where the trapping efficiency was higher further from the coast (Roberts et al 2015;Xu et al 2016).…”

Section: Discussionmentioning

confidence: 99%

Factors controlling sediment trapping in two freshwater tidal wetlands in the Biesbosch area, The Netherlands

2017

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Purpose A thorough understanding of mechanisms controlling sedimentation and erosion is vital for a proper assessment of the effectiveness of delta restoration. Only few field-based studies have been undertaken in freshwater tidal wetlands. Furthermore, studies that measured sediment deposition in newly created wetlands are also sparse. This paper aims to identify the factors controlling the sediment trapping of two newly created freshwater tidal wetlands. Materials and methods Two recently re-opened polder areas in the Biesbosch, The Netherlands are used as study area. Field measurements of water levels, flow velocities, and turbidity at both the in-and outlet of the areas were carried out to determine the sediment budgets and trapping efficiencies under varying conditions of river discharge, tide, and wind in the period 2014-2016. Results and discussion Short-term sediment fluxes of the two study areas varied due to river discharge, tide, and wind. A positive sediment budget and trapping efficiency was found for the first study area, which has a continuing supply of river water and sediment. Sediment was lost from the second study area which lies further from the river and had a lower sediment supply. The daily sediment budget is positively related to upstream river discharge, and in general, export takes place during ebb and import during flood. However, strong wind events overrule this pattern, and trapping efficiencies decrease for increasing wind strengths at mid-range river discharges and for the highest river discharges due to increased shear stress. Conclusions Delta restoration, based on sedimentation to compensate for sea-level rise and soil subsidence, could only be effective when there is a sufficient supply of water and sediment. Management to enhance the trapping efficiency of the incoming sediment should focus on directing sufficient river flow into the wetland, ensuring the supply of water and sediment within the system during a tidal cycle, creating sufficiently large residence time of water within the polder areas for sediment settling, and decreasing wave shear stress by the establishment of vegetation or topographic irregularities.

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“…There are only a handful of studies that have attempted to tie the bulk sedimentary properties of a recent deposit to sedimenttransport properties in the river that created it (Törnqvist et al, 2007;Kim et al, 2009;Giosan et al, 2013;Day et al, 2016), and we are unaware of any with a subsurface data set as rich as the one available for the ACS. While many workers have published on the "river side" issues concerning diversions, including the sediment available (Kesel, 1988;Blum and Roberts, 2009;Allison et al, 2012) and the physics of extracting sediment from the trunk channel (Allison and Meselhe, 2010;Meselhe et al, 2012;Nittrouer et al, 2012a;Allison et al, 2013), only recently have researchers begun to investigate "basin side" issues that impact SRE (Xu et al, 2016). The availability of detailed sediment-transport data from the modern Lower Mississippi River (LMR) (Allison et al, 2012) provides a unique opportunity to connect fluvial sediment budgets to the sediments preserved in the delta.…”

Section: Measuring Sediment Retention Efficiencymentioning

confidence: 99%

Efficient retention of mud drives land building on the Mississippi Delta plain

Esposito¹,

Shen²,

Törnqvist³

et al. 2017

Preprint

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Abstract. Many of the world's deltas – home to major population centers – are rapidly degrading due to reduced sediment supply, making these systems less resilient to increasing rates of relative sea-level rise. The Mississippi Delta faces some of the highest rates of wetland loss in the world. As a result, multi-billion dollar plans for coastal restoration by means of river diversions are currently nearing implementation. River diversions aim to bring sediment back to the presently sediment-starved delta plain. Within this context, sediment retention efficiency (SRE) is a critical parameter because it dictates the effectiveness of river diversions. Several recent studies have focused on land building along the open coast, showing SREs as low as 5 %. Here we measure the SRE of a large relict crevasse splay in an inland, vegetated setting that serves as an appropriate model for river diversions. By comparing the mass fraction of sand in the splay deposit to the estimated sand fraction that entered it during its life cycle we find that this mud-dominated sediment body has an SRE of ≥ 75 %, i.e., dramatically higher than its counterparts on the open coast. Our results show that transport pathways for mud are critical for delta evolution and that SRE is highly variable across a delta. We conclude that sediment diversions located in settings that are currently still vegetated are likely to be the most effective in reversing land loss and providing long-term sustainability.

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Implications of Texture and Erodibility for Sediment Retention in Receiving Basins of Coastal Louisiana Diversions

Cited by 54 publications

References 41 publications

Influence of Sediment Cohesion on Deltaic Morphodynamics and Stratigraphy Over Basin‐Filling Time Scales

Influence of Sediment Cohesion on Deltaic Morphodynamics and Stratigraphy Over Basin‐Filling Time Scales

Factors controlling sediment trapping in two freshwater tidal wetlands in the Biesbosch area, The Netherlands

Efficient retention of mud drives land building on the Mississippi Delta plain

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