Observations on Stream Discharge and Competence at Mosaic Canyon, Death Valley, California

Beaumont, Peter; Oberlander, Theodore M.

doi:10.1130/0016-7606(1971)82[1695:oosdac]2.0.co;2

Cited by 20 publications

(18 citation statements)

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“…Researchers often try to match either the Reynolds or the Froude number between systems, in the attempt to create similar transport conditions between experimental and natural scales. Our experimental channels have subcritical Froude numbers (Table 1) that are reasonable for alluvial rivers and delta channels, but conflict with some alluvial fan studies that observed supercritical flow, so that in this aspect, our experiments may not be directly scalable to natural fans [ Rahn , 1967; Beaumont and Oberlander , 1971]. However, because our process arguments are focused on bulk grain mechanics that are not likely to depend strongly on Froude‐related hydrodynamics, a conflict in Froude scaling would be acceptable for the purposes of our study.…”

Section: Methodsmentioning

confidence: 99%

Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth

2012

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[1] River deltas and alluvial fans have channelization and deposition dynamics that are not entirely understood, but which dictate the evolution of landscapes of great social, economic, and ecologic value. Our lack of a process-based understanding of fan dynamics hampers our ability to construct accurate prediction and hazard models, leaving these regions vulnerable. Here we describe the growth of a series of experimental alluvial fans composed of a noncohesive grain mixture bimodal in size and density. We impose conditions that simulate a gravel/sand fan prograding into a static basin with constant water and sediment influx, and the resulting fans display realistic channelization and avulsion dynamics. We find that we can describe the dynamics of our fans in terms of a few processes: (1) an avulsion sequence with a timescale dictated by mass conservation between incoming flux and deposit volume; (2) a tendency for flow to reoccupy former channel paths; and (3) bistable slopes corresponding to separate entrainment and deposition conditions for grains. Several important observations related to these processes are: an avulsion timescale that increases with time and decreases with sediment feed rate; fan lobes that grow in a self-similar, quasi-radial pattern; and channel geometry that is adjusted to the threshold entrainment stress. We propose that the formation of well-defined channels in noncohesive fans is a transient phenomenon resulting from incision following avulsion, and can be directly described with dual transport thresholds. We present a fairly complete, process-based description of the mechanics of avulsion and its resulting timescale on our fans. Because the relevant dynamics depend only on threshold transport conditions and conservation of mass, we show how results may be directly applied to field-scale systems.

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Section: Methodsmentioning

confidence: 99%

Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth

2012

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“…The winnowed sediment typically is sand and clay but can range in size to pebbles and cobbles (e.g. Beaumont and Oberlander 1971). This sediment is moved farther down-fan, possibly even to neighbouring environments off the fan.…”

Section: Surficial Reworking By Watermentioning

confidence: 99%

Alluvial Fan Processes and Forms

Blair¹,

McPherson²

1994

Geomorphology of Desert Environments

192

266

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“…On most fans, especially dry-region fans, whether debris-flow or fluvially-dominant, sediment supply is episodic, related to major storm and flood events (Beaumont and Oberlander, 1971;Whipple et al, 1998;Arzani, 2005;Mather and Hartley, 2005). On any one fan the water-to-sediment ratio may vary during a storm (Wells and Harvey, 1987) and may vary downfan (Pierson and Scott, 1985), resulting in a complex of depositional facies, but with the overall pattern, facies-dominance and the differences between fans reflecting the gross catchment controls over water and sediment production.…”

Section: Fluvial Processesmentioning

confidence: 99%

Dryland Alluvial Fans

Harvey

2011

Arid Zone Geomorphology

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Observations on Stream Discharge and Competence at Mosaic Canyon, Death Valley, California

Cited by 20 publications

References 0 publications

Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth

Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth

Alluvial Fan Processes and Forms

Dryland Alluvial Fans

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