The Intrusion of Fine Sediments into a Stable Gravel Bed

Beschta, Robert L.; Jackson, William L.

doi:10.1139/f79-030

Cited by 248 publications

(247 citation statements)

References 3 publications

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“…Relative seal thickness expressed as a ratio to the 90th percentile fraction of the framework material, T/D 90 , equals 2.6 for natural bed material finer than 32 mm or 3.6 for the experimental gravel. These values agree well with those measured in experimental channels, 2.4-3.0 [Diplas and Parker, 1985] and 2.5-5.0 [Beschta and Jackson, 1979]. In the study period (1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986), storm flows that had magnitudes estimated to be capable of causing the maximum deposition of fine sediment cited above (40 kg m 2 ) were relatively frequent in Jacoby and Prairie Creeks, but relatively infrequent in North Caspar Creek.…”

Section: Deposition Of Fine Sediment In Gravel Bedssupporting

confidence: 91%

“…Solid-walled containers have been used in several exper-iments to measure sediment infiltration (Slaney et al [1977], Beschta and Jackson [1979], Carting [1984], and Frostick et al [1984] among others). Such containers collect only the sediment that enters a volume of bed material through the surface interstices and excludes sediment that is introduced laterally by intergravel flow, which can have high instantaneous accelerations due to turbulence near the bed.…”

Section: Infiltration Of Fine Sedimentmentioning

confidence: 99%

“…Such containers collect only the sediment that enters a volume of bed material through the surface interstices and excludes sediment that is introduced laterally by intergravel flow, which can have high instantaneous accelerations due to turbulence near the bed. Gravity fall has been found to be the dominant mode of ingress of fine sediment into gravel beds [Einstein, 1968;Slaney et al, 1977;Beschta and Jackson, 1979]. However, Curling [ 1984] found that impermeable container walls reduced trapping efficiency to 62% due to elimination of intergravel flow that could distribute sediment throughout a sample.…”

Section: Infiltration Of Fine Sedimentmentioning

confidence: 99%

“…Log-transformed values of accumulation of fine sediment (0.25 < D < 2 mm) averaged for all gravel can lines and describing this relation passes through points selected from Beschta and Jackson's [1979] experiment to best represent conditions in the three stream channels (Froude number less than 1 and introduced sediment 0.5 mm in diameter).…”

Section: Deposition Of Fine Sediment In Gravel Bedsmentioning

confidence: 99%

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Sediment transport and resulting deposition in spawning gravels, north coastal California

Lisle¹

1989

Water Resources Research

288

257

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Incubating salmonid eggs in streambeds are often threatened by deposition of fine sediment within the gravel. To relate sedimentation of spawning gravel beds to sediment transport, infiltration of fine sediment (<2 mm in diameter) into clean gravel beds, bed material size distributions, scour-fill depths, and sediment transport during 10 storm flow events were measured in three streams of north coastal California. Although suspended sediment comprised most (75-94%) of the clastic load during storm flows, bed load material (0.25-2 mm) accounted for most (70-78%) of the fine sediment accumulated in experimental gravel implanted in the streambeds. Sand trapped in the interstices of the top several centimeters formed a seal that impeded deeper deposition of very fine sand and finer material. The seal was responsible at least in part for a decrease in the rate of fine-sediment accumulation with increasing cumulative bed load transport. Areas of the streambeds commonly scoured or filled 0.1 m or more during storm flows, and thus scour and fill commonly created a sandy layer at least as thick as the seal formed by sediment infiltration. Scour could erode eggs laid in the bed and expose deeper levels of the bed to infiltration by fine sediment, but at the same time could allow fine sediment to be winnowed away. Great temporal and spatial variation in sedimentation in these streams suggests that individual storms of moderate size pose a threat to eggs in many but not all areas selected by fish for spawning.

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Section: Deposition Of Fine Sediment In Gravel Bedssupporting

confidence: 91%

Section: Infiltration Of Fine Sedimentmentioning

confidence: 99%

Section: Infiltration Of Fine Sedimentmentioning

confidence: 99%

Section: Deposition Of Fine Sediment In Gravel Bedsmentioning

confidence: 99%

See 2 more Smart Citations

Sediment transport and resulting deposition in spawning gravels, north coastal California

Lisle¹

1989

Water Resources Research

288

257

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“…Beschta and Jackson, 1979], but very little additional coarsening occurred at higher flows. Larger particles typically rolled into contact with a static particle of similar size and stopped.…”

Section: Experimental Observationsmentioning

confidence: 99%

Stabilizing self‐organized structures in gravel‐bed stream channels: Field and experimental observations

Church¹,

Hassan²,

Wolcott³

1998

Water Resources Research

317

359

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IntroductionMost alluvial stream channels change remarkably little over periods that can be as long as years or decades, even though they may be regularly subjected to sediment-transporting flows. Stream channels are stability-seeking entities. What we see is the product of a succession of changes; the morphology that persists is that which is most nearly stable in face of the usually imposed flows. Stability is gained when stream energy can be dissipated without the accomplishment of significant channel-deforming work, even though sediment transfer, including the exchange of sediment at the channel boundaries, may still occur. Energy-dissipating structures develop at all morphological scales within the channel, including the scales of channel pattern, pool and riffle, and sedimentary bed forms. However, the most basic level at which stability develops in gravel-bed channels is that of the granular boundary materials, the potentially mobile sediments themselves.Grains are entrained in stream channels when the force of water acting on the alluvial bed material overcomes particle inertia. Shields [1936] expressed the force balance at entrainment as a "mobility number," a function of the ratio of fluid shear stress exerted on the bed to (submerged) particle weight. [Gomez, 1993]. None of these factors eliminate the fundamental effect of particle weight. However, when particles become interlocked, the relative effect of particle weight becomes comparatively less dominant.• In gravel-bed streams with low rates of bed material transport, we have observed much more complex grain structures, which we call stone cells [cf. Gustavson, 1974]. The purpose of this paper is to describe these features, to obtain some phenomenological understanding of the conditions under which they develop and persist, and to explore their influence on the promotion of streambed stability. 2.Field Observations

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Deposition and storage of fine-grained sediment within the main channel system of the River Tweed, Scotland

Owens

Walling

Leeks

1999

Earth Surf. Process. Landforms

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This paper assesses the importance of deposition and storage of fine-grained (c.`150 "m) sediment on the floodplains and beds of the main (non-tidal) channels of the River Tweed (4390 km 2 ), Scotland, and two of its tributaries (River Teviot and Ettrick Water). Caesium-137 analysis of floodplain sediment cores has been used to estimate average rates of overbank sedimentation during the last 30 to 40 years. Average values for individual transects ranged from 0Á16 to 2Á18 kg m À2 a À1(0Á13 to 2Á2 mm a À1 ). The mean for the 10 transects investigated was 1Á29 kg m À2 a À1 (1Á3 mm a À1 ). The total amount of fine sediment deposited was estimated to be about 44 000 t a À1. The fine-grained sediment stored in the channel bed was quantified using resuspension techniques. Average values for individual sites ranged from 0Á12 to 0Á96 kg m À2. The mean for the 10 sites investigated was 0Á56 kg m À2. The total amount of sediment stored on the channel bed of the main channel system at the time of sampling was estimated to be about 4300 t. Comparison of these estimates of floodplain and channel storage with the estimated suspended sediment load for the River Tweed at the downstream gauging site at Norham, indicates that floodplain sedimentation and channel bed storage represent about 40 and 4 per cent, respectively, of the annual load of fine sediment delivered to the main channel system. Erosion of channel banks will reintroduce the equivalent of about 30 per cent of the floodplain-deposited sediment back into the channel. The residence time of the fine-grained sediment stored on the channel bed is probably less than one year, but that of sediment deposited on the floodplain is likely to be considerably longer. Conveyance losses associated with overbank deposition have important implications for the routing of sediment through fluvial systems and the interpretation of downstream sediment yields.

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The Intrusion of Fine Sediments into a Stable Gravel Bed

Cited by 248 publications

References 3 publications

Sediment transport and resulting deposition in spawning gravels, north coastal California

Sediment transport and resulting deposition in spawning gravels, north coastal California

Stabilizing self‐organized structures in gravel‐bed stream channels: Field and experimental observations

Deposition and storage of fine-grained sediment within the main channel system of the River Tweed, Scotland

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