Bed load sediment transport in ephemeral and perennial gravel bed streams

Almedeij, Jaber; Diplas, Panayiotis

doi:10.1029/2005eo440002

Cited by 28 publications

(26 citation statements)

References 4 publications

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“…They appear to delineate an upper limit on bed-load transport rates, as governed by the efficiency of energy expenditure ( Fig. 2) and, although there are differences in the behavior of ephemeral and perennial rivers and flumes, to be part of the same overall trend that relates bed-load transport to the flow characteristics (2,5). The averaged data suggest that, at high transport rates, there is a straightforward relation between the bed-load transport efficiency attained in both rivers and flumes and the median particle size of the bed load (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…That is, to articulate a limit formula for potential transport. I accomplish this by incorporating an empirical, particle-size-dependent term for bed-load transport efficiency into an existing formulation that has been shown to be relatively successful in predicting bed-load transport in gravel-bed rivers (1,2), where the dominant bed material size ranges from 0.002 to ϳ0.2 m.…”

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The potential rate of bed-load transport

Gómez

2006

Proc. Natl. Acad. Sci. U.S.A.

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Averages of measurements made in three rivers characterized by a high availability of sediment in relation to runoff, and comparable data that represent the high end of the range of transport rates observed during three sets of laboratory experiments, confirm there is an upper, particle-size-dependent limit to bed-load transport efficiency. Incorporating the regression relation derived from these six diverse and unrelated data sets into R. A. Bagnold's classic formulation yields ib ‫؍‬ [0.0115⅐D50 ؊0.51 ]͞0.63. This straightforward scale correlation can be used to estimate the potential rate of bed-load transport (for average conditions) in gravel-bed rivers when sediment transport is constrained neither by the supply of sediment to nor by the amount of sediment available in the channel. The independent application of this empirical limit formula to two rivers with applicable bed-load transport regimes reveals a good (؎10%) correspondence between average observed and predicted transport rates.bed-load transport efficiency ͉ gravel-bed rivers ͉ sediment transport B ed-load transport provides the major process linkage between the hydraulic and material conditions that govern river-channel morphology, and knowledge of bed-load movement is required not only to elucidate the causes and consequences of changes in fluvial form but also to make informed management decisions that affect a river's function. Unfortunately the collection of high-quality bed-load transport data is an expensive and time-consuming task, and for many practical purposes recourse is made to a bed-load transport formula (1). The ability of any formula to predict the bed-load transport rate under given flow conditions is predicated on the assumption that it is possible to describe the rate at which bed load is transported in terms of measurable hydraulic and sedimentological quantities (1). Even assuming there are no limitations on sediment supply, the task is complicated by the realization that, at all but the highest flows, the movement of heterogeneous sediment is governed by absolute and relative size effects, so that the local transport rate depends on the population of particles immediately available at the bed surface (2). However, little is known about how the composition of the bed surface changes over time, and despite more than a century of effort it is not yet possible to make reliable predictions of bed-load transport rates. One way to address this impasse is to remove the restrictions imposed by sediment supply and availability from the problem and determine how much bed load a river is capable of transporting, rather than how much it actually transports. That is, to articulate a limit formula for potential transport. I accomplish this by incorporating an empirical, particle-size-dependent term for bed-load transport efficiency into an existing formulation that has been shown to be relatively successful in predicting bed-load transport in gravel-bed rivers (1, 2), where the dominant bed material size ranges from 0.002 to ϳ0.2 m.G. K. ...

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

The potential rate of bed-load transport

Gómez

2006

Proc. Natl. Acad. Sci. U.S.A.

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“…This normalization will lead to meaningful efficiencies that are comparable, if the relation between sediment mass transport and stream power is linear. Linear relations appear to be associated with transport-limited systems (Reid and Laronne, 1995;Almedeij and Diplas, 2005). For example, before a fire, a steep mountain perennial stream with an armored channel was a supply-limited system and had a non-linear relation (Moody and Martin, 2001a,b) similar to other perennial streams (Reid and Laronne, 1995).…”

Section: Introductionmentioning

confidence: 95%

Post-wildfire erosion response in two geologic terrains in the western USA

2008

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“…It is well documented that the latter type is less prone to displaying bed armoring at low flow [Laronne et al, 1994]. A very interesting question in this regard was recently posed by Almedeij and Diplas [2005]: Do perennial and ephemeral streams represent different parts of the same general continuum relating transport rates to flow strength? This question cannot be answered in the absence of information as to how both bed elevation and bed surface size distribution evolve during flood events.…”

Section: Introductionmentioning

confidence: 99%

One‐dimensional modeling of bed evolution in a gravel bed river subject to a cycled flood hydrograph

Wong¹,

Parker

2006

J. Geophys. Res.

105

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[1] How does a mountain river adjust to accommodate repeated flood hydrographs? Do flood hydrographs cause major cycles of aggradation and degradation of the river bed? Here flume experiments are used to explore this problem. The response of a gravel bed river to repeated floods is modeled in the simplest possible way. The gravel is well sorted, the flume is operated in sediment feed mode, and the gravel feed rate is held constant. The flow discharge, on the other hand, is specified in terms of the repetition of the same hydrograph until mobile bed equilibrium (averaged over the hydrograph) is achieved. The results of the experiments demonstrate a remarkable trade-off. In a short inlet "boundary layer" (transition region) the bed elevation and bed slope fluctuate cyclically with the changing flow discharge, while the gravel transport rate remains nearly equal to the constant feed rate. Downstream of this short reach, however, the bed elevation and bed slope do not fluctuate in response to the hydrograph; all the fluctuation is transferred to the gravel transport rate. These results are verified in terms of onedimensional analytical and numerical modeling. This modeling shows that the trade-off is inevitable as long as the morphologic response time of the reach in question is sufficiently long compared to the duration of a single hydrograph. The implication is that gravel bed rivers tend to adjust to hydrographs so as to minimize the response of the bed and maximize the response of the bed load transport rate to fluctuating flow discharge.Citation: Wong, M., and G. Parker (2006), One-dimensional modeling of bed evolution in a gravel bed river subject to a cycled flood hydrograph,

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Bed load sediment transport in ephemeral and perennial gravel bed streams

Cited by 28 publications

References 4 publications

The potential rate of bed-load transport

The potential rate of bed-load transport

Post-wildfire erosion response in two geologic terrains in the western USA

One‐dimensional modeling of bed evolution in a gravel bed river subject to a cycled flood hydrograph

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