Mechanics of river mouth bar formation: Implications for the morphodynamics of delta distributary networks

Edmonds, Douglas A.; Slingerland, Rudy

doi:10.1029/2006jf000574

Cited by 221 publications

(440 citation statements)

References 25 publications

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“…We take f L ≈ 0.58 and f W ≈ 0.71, consistent with modern riverdominated deltas [Edmonds and Slingerland, 2007]. From the geometric series F k = P k i¼0 r k = (r k+1 − 1)/(r − 1) we obtain formulas for net channel network wetted length L k = P k i¼0 2n k ' k and area A k = P k i¼0 n k w k ' k in a tree of order k. The curve in …”

Section: Discussionmentioning

confidence: 99%

Delta allometry: Growth laws for river deltas

Wolinsky¹,

Edmonds

Martin³

et al. 2010

Geophysical Research Letters

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[1] Under projected scenarios of sea-level rise, subsidence, and sediment starvation many deltas around the world are expected to drown. Delta growth dynamics, which determine the ability of a delta to adapt to these changes, are poorly understood due to the difficulty of measuring change in slowly evolving landscapes. We use timeseries imagery of experimental, numerical, and field-scale deltas to derive four laws that govern the growth of riverdominated deltas. Land area grows at a constant rate in the absence of relative sea level change, while wetted area keeps pace, maintaining a constant wetted fraction over the delta surface. Scaling of edge-lengths versus areas suggests delta shorelines are nonfractal, even though the channel network is fractal. Consequently channel-edge length, which provides critical habitat, grows more rapidly than delta area. These laws provide a blueprint for delta growth that will aid in delta restoration and help predict how existing deltas will evolve. Citation: Wolinsky, M.

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Section: Discussionmentioning

confidence: 99%

Delta allometry: Growth laws for river deltas

Wolinsky¹,

Edmonds

Martin³

et al. 2010

Geophysical Research Letters

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“…Several studies document consistent downstream trends in the width and depth of established deltaic channels [Andrén, 1994;Olariu and Bhattacharya, 2006;Edmonds and Slingerland, 2007;Edmonds et al, 2011b;Sassi et al, 2012]. However, only a few studies have documented channel network evolution through time.…”

Section: Delta Channel Network Evolutionmentioning

confidence: 99%

The morphology and evolution of channels on the Wax Lake Delta, Louisiana, USA

Shaw

Mohrig

Whitman³

2013

JGR Earth Surface

102

108

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[1] River deltas are classic depositional systems, but a growing body of literature shows that their channel networks can be erosional. Furthermore, this erosion can attack channel beds of consolidated mud that acts as bedrock. To better understand the channel networks of natural deltas and engineered river diversions, we investigate bathymetric and planimetric change, bed cover, and sediment transport in the Wax Lake Delta (WLD) in coastal Louisiana, USA. Channels have eroded up to 40% of modern flow depth between the WLD's initiation in 1973 and 1999. Aerial image analysis shows that channels have widened by 11% between 1991 and 2009, forcing the downstream migration of islands. Channel beds are composed of 85-98% muddy bedrock, with the remainder covered by alluvial sands. Water velocity, grain size, and suspended sand concentration measurements during the 2009 spring flood show that almost all available grain sizes are transported in suspension. Flow was supply limited during this period, with the calculated sand concentration at the height of the bed load layer is 1-4 orders of magnitude smaller than predicted for saturated sand transport. We test "the cover effect" and "the tools effect" previously proposed for bedrock erosion in upland river channels. Bedrock erosion and alluvial cover are anti-correlated (the cover effect), but the observations do not closely follow previously proposed relationships. The difference in erosion rate between clear water and sand-rich water shows that abrasion by sand (the tools effect) accounts for 51% ± 56% of bedrock erosion when it is present.

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“…However the total sand body extent will depend on the lateral connectivity between these sand rich features (Ravenne, et al 1989 (Ashworth, et al 2011), experimentally (Rowland, Dietrich and Stacey 2010) as well as numerically (Chatanantavet, Lamb and Nittrouer 2012;Nardin, et al 2013;Leonardi, et al 2013;Edmonds and Slingerland, 2007;Edmonds, et al 2010). Previous work on mouth bars, for example, includes their formation of river dominated delta networks (Edmonds and Slingerland, 2007) but there has also been studies focussed on sub-aqueous levee formation (Rowland, Dietrich and Stacey 2010). The effects of tides (Leonardi, et al 2013) and waves (Nardin, et al 2013) on the formation of deltaic mouth bars has been investigated.…”

Section: Theory and Methodsmentioning

confidence: 99%

Establishing 3D Numerical Reservoir Analogues - Modelling the Formation of Sand Bodies in Deltaic Environments

Vegt¹,

Storms²,

Walstra³

2014

Proceedings

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SUMMARYThe assessment and production of hydrocarbon resources incorporates geological models created from core and wireline well data, as well as seismic data. This data is spatially discrete but is used create a spatially continuous model. However, the heterogeneity within depositional environments is on a smaller spatial scale than the available data resolution. The field data is therefore supplemented with relevant analogue data, often from deposits which differ in various aspects from the actual reservoir being assessed. To improve the correlation between analogues and the reservoir being studied, it is proposed that 3D numerical analogues are used in addition to the current outcrop analogues. These 3D numerical analogues can be created through process based numerical modelling and can more closely match the conditions of the reservoir being studied. In this presentation we propose a workflow to create and implement 3D numerical outcrops. We go on to show an initial stage of a proof of concept for the workflow. It is shown that using the software Delf3D, it is possible to simulate the sand bodies found in deltaic deposits, which can later act as hydrocarbon reservoirs.

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Mechanics of river mouth bar formation: Implications for the morphodynamics of delta distributary networks

Cited by 221 publications

References 25 publications

Delta allometry: Growth laws for river deltas

Delta allometry: Growth laws for river deltas

The morphology and evolution of channels on the Wax Lake Delta, Louisiana, USA

Establishing 3D Numerical Reservoir Analogues - Modelling the Formation of Sand Bodies in Deltaic Environments

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