Modelling hydrodynamics in the Rio Paraná, Argentina: An evaluation and inter-comparison of reduced-complexity and physics based models applied to a large sand-bed river

Nicholas, A. P.; Sandbach, S. D.; Ashworth, Philip; Amsler, Mario L.; Best, James L.; Hardy, Richard J.; Lane, Stuart N.; Orfeo, Oscar; Parsons, Daniel R.; Reesink, A.; Smith, Gregory H. Sambrook; Szupiany, R. N.

doi:10.1016/j.geomorph.2012.05.014

Cited by 39 publications

(51 citation statements)

References 67 publications

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“…In secondary channel bars, the stability is such that allows grass vegetation to develop. This tendency refl ects reports by Nicholas et al (2013), which show that bar and island stability may be sensitive to hydrologic regime, especially because greater variability in fl ood magnitude encourages the formation of emergent bars that can be converted into stable islands by vegetation colonization.…”

Section: Discussionsupporting

confidence: 82%

“…This condition also generates the bar-island channel in the τcr:τ0 > 1 sector. Unlikely the origin of other bars, as postulated by Ashworth et al (2000), Sarma (2005) and Njenga et al (2013) and others, attachment bars do not arise from mega bedforms such as dunes and sand waves. A rather complex process is involved though.…”

Section: Discussionmentioning

confidence: 64%

“…Earlier studies FRANZI-NELLI, 2002, 2005;SARMA, 2005, LATRUBESSE, 2008ROZO et al, 2012;NICHOLAS et al, 2013;REESINK et al, 2014) indicate that fl uvial bars in anabranching rivers are deposited in sites with: (i) divergent secondary fl ows (ii) fl ow competence reduction (specifi c stream power and fl ow shear stress) and (iii) sand availability. These conditions were present in the study site.…”

Section: Discussionmentioning

confidence: 99%

“…As for anastomosing rivers, there have recently been some studies on the mechanisms of bar formation and heterogeneity FRANZINELLI 2002, 2005;SARMA, 2005;LATRUBESSE, 2008;ROZO et al, 2012, NICHOLAS et al, 2012NICHO-LAS et al, 2013;REESINK et al, 2014).…”

Section: Introdutionmentioning

confidence: 99%

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Fluvial Processes in Attachment Bars in the Upper Paraná River, Brazil

Santos

Stevaux

Assine

2017

Rev. Bras. Geomorfol.

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Abstract:Bars are semi-submerged fluvial forms associated with the availability of sediments and a temporal dynamic, whose dimensions are controlled by the fl ow and depth of the channel. Attachment bars are very common in large anabranching river systems and play an important role in island formation and ecology. The Upper Paraná River exhibits an anabranching pattern characterized by channels of diff erent sizes, separated by islands and bars. The objective of this work is to present the processes involved in the formation and development of attachment bars in Santa Rosa Island, situated in Porto Rico, State of Parana, Southern Brazil. Acquisition campaigns were performed to obtain data on channel hydraulics (ADCP equipment), morphometry (Echo-sound profi les) and textural parameters (grain-size analyses) at high and medium water levels. Santa Rosa Island divides the fl ow into two channels of distinct hydraulic and sedimentary dynamics. Flow diversion produces a decrease in fl ow velocity and consequent sediment deposition near the upstream end of Santa Rosa Island. The formation and maintenance of attachment bars in Santa Rosa Island is related to fl ow competence reduction and the occurrence of divergent currents. Vegetation cover and fl ow regime control its permanence.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Introdutionmentioning

confidence: 99%

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Fluvial Processes in Attachment Bars in the Upper Paraná River, Brazil

Santos

Stevaux

Assine

2017

Rev. Bras. Geomorfol.

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“…Following, for example, Nicholas (2003), Lesser et al (2004), Nicholas et al (2012), and Schuurman et al (2013), a constant uniform bed roughness was applied, assuming bed forms were subgrid and thus captured by the bed roughness parameter. We applied a uniform Nikuradse k s of 0.15 m, which is recomputed to a Chézy roughness in Delft3D.…”

Section: Default Model Settings and Boundary Conditionsmentioning

confidence: 99%

Network response to disturbances in large sand-bed braided rivers

2016

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Abstract. The reach-scale effects of human-induced disturbances on the channel network in large braided rivers are a challenge to understand and to predict. In this study, we simulated different types of disturbances in a large braided river to get insight into the propagation of disturbances through a braided channel network. The results showed that the disturbances initiate an instability that propagates in the downstream direction by means of alteration of water and sediment division at bifurcations. These adjustments of the bifurcations change the migration and shape of bars, with a feedback to the upstream bifurcation and alteration of the approaching flow to the downstream bifurcation. This way, the morphological effect of a disturbance amplifies in the downstream direction. Thus, the interplay of bifurcation instability and asymmetrical reshaping of bars was found to be essential for propagation of the effects of a disturbance. The study also demonstrated that the large-scale bar statistics are hardly affected.

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Quantifying the patterns and dynamics of river deltas under conditions of steady forcing and relative sea level rise

2016

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Understanding deltaic channel dynamics is essential to acquiring knowledge on how deltas respond to environmental changes, as channels control the distribution of water, sediment, and nutrients. Channel-resolving morphodynamic models provide the basis for quantitative study of channel-scale dynamics, but they need to be properly assessed with a set of robust metrics able to quantitatively characterize delta patterns and dynamics before being used as predictive tools. In this work we use metrics developed in the context of delta formation, to assess the morphodynamic results of DeltaRCM, a parcel-based cellular model for delta formation and evolution. By comparing model results to theoretical predictions and field and experimental observations, we show that DeltaRCM captures the geometric growth characteristics of deltas such as fractality of channel network, spatial distribution of wet and dry surfaces, and temporal dynamics of channel-scale processes such as the decay of channel planform correlation. After evaluating the ability of DeltaRCM to produce delta patterns and dynamics at the scale of channel processes, we use the model to predict the deltaic response to relative sea level rise (RSLR). We show that uniform subsidence and absolute sea level rise have similar effects on delta evolution and cause intensified channel branching. Channel network fractality and channel mobility increase with higher-RSLR rates, while the spatial and temporal scales of avulsion events decrease, resulting in smaller sand bodies in the stratigraphy. Our modeling results provide the first set of quantitative predictions of the effects of RSLR on river deltas with a specific focus on the distributary channel network.

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Modelling hydrodynamics in the Rio Paraná, Argentina: An evaluation and inter-comparison of reduced-complexity and physics based models applied to a large sand-bed river

Cited by 39 publications

References 67 publications

Fluvial Processes in Attachment Bars in the Upper Paraná River, Brazil

Fluvial Processes in Attachment Bars in the Upper Paraná River, Brazil

Network response to disturbances in large sand-bed braided rivers

Quantifying the patterns and dynamics of river deltas under conditions of steady forcing and relative sea level rise

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