A field comparison of three pressure-difference bedload samplers

Ryan, Sandra E.; Porth, Laurie S.

doi:10.1016/s0169-555x(99)00059-8

Cited by 51 publications

(58 citation statements)

References 21 publications

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“…By comparison, the upper size limit of the Helley-Smith sampler is about 76 mm, which potentially truncates the upper end of the bedload distribution. However, analyses of sediment obtained from settling ponds at several sites in the region indicate that 85-90 per cent (by weight) of the grains trapped in the ponds would pass easily through the opening of a Helley-Smith sampler (Wilcox et al, 1996;Ryan and Porth, 1999), suggesting that the truncation is relatively minor. Regardless of the sampler deployed, all measurements made for a site use the same type of device.…”

Section: Methodsmentioning

confidence: 99%

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Coarse sediment transport in mountain streams in Colorado and Wyoming, USA

Ryan

Porth

Troendle³

2005

Earth Surf Processes Landf

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Since the early 1990s, US Forest Service researchers have made thousands of bedload measurements in steep, coarse-grained channels in Colorado and Wyoming, USA. In this paper we use data from 19 of those sites to characterize patterns and rates of coarse sediment transport for a range of channel types and sizes, including step-pool, plane-bed, pool-riffle, and near-braided channels. This effort builds upon previous work where we applied a piecewise regression model to (1) relate flow to rates of bedload transport and (2) define phases of transport in coarse-grained channels. Earlier, the model was tested using bedload data from eight sites on the Fraser Experimental Forest near Fraser, Colorado. The analysis showed good application to those data and to data from four supplementary channels to which the procedure was applied. The earlier results were, however, derived from data collected at sites that, for the most part, have quite similar geology and runoff regimes. In this paper we evaluate further the application of piecewise regression to data from channels with a wider range of geomorphic conditions. The results corroborate with those from the earlier work in that there is a relatively narrow range of discharges at which a substantial change in the nature of bedload transport occurs. The transition from primarily low rates of sand transport (phase I) to higher rates of sand and coarse gravel transport (phase II) occurs, on average, at about 80 per cent of the bankfull (1·5-year return interval) discharge. A comparison of grain sizes moved during the two phases showed that coarse gravel is rarely trapped in the samplers during phase I transport. Moreover, the movement and capture of the D 16 to D 25 grain size of the bed surface seems to correspond with the onset of phase II transport, particularly in systems with largely static channel surfaces. However, while there were many similarities in observed patterns of bedload transport at the 19 studied sites, each had its own 'bedload signal' in that the rate and size of materials transported largely reflected the nature of flow and sediment particular to that system. Published in 2005 by John Wiley & Sons, Ltd.

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Section: Methodsmentioning

confidence: 99%

“…Hayden Creek). One common difficulty when fitting any regression model to bedload data is the non-normality and heterogeneous variance of the model results (Ryan and Porth, 1999;. When this occurs, the standard errors of the estimates for each of the parameters are suspect.…”

Section: Bedload Rating Curvesmentioning

confidence: 99%

Coarse sediment transport in mountain streams in Colorado and Wyoming, USA

Ryan

Porth

Troendle³

2005

Earth Surf Processes Landf

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“…For example, [27][28][29] observed that bag size, mesh width and sampling duration affected the sampling efficiency, [30] found that the orientation of the sampler and its size had an effect, and [31,32] showed that thickness of the sampler wall mattered. Several studies revealed that different types of Helley-Smith samplers yielded different sampling results [32][33][34][35][36][37][38][39][40][41]. Others reported a satisfactory sampling efficiency for sand to medium gravel particles [9,[42][43][44] (see [45] for a summary of this research).…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Coarse Bedload Transport Measured with Bedload Traps and Helley-Smith Samplers

et al. 2008

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Gravel bedload transport rates were measured at eight study sites in coarse-bedded Rocky Mountain streams using 4-6 bedload traps deployed across the stream width and a 76 by 76 mm opening Helley Smith sampler. Transport rates obtained from bedload traps increased steeply with flow which resulted in steep and well-defined transport rating curves with exponents of 8 to 16. Gravel transport rates measured by the HelleySmith sampler started with much higher transport rates during low flows and increased less steeply, thus fitted bedload rating curves were less steep with exponents of 2 to 4. Transport rates measured with both samplers approached similar results near or above bankfull flow, but at 50 % of bankfull, transport rates from the bedload traps were 2-4 orders of magnitude lower than those obtained from the Helley-Smith sampler. The maximum bedload particle sizes also differed between the two samplers. They were smaller in the bedload traps than the Helley-Smith sampler at low flows, while at higher flows bedload traps collected larger particles than the Helley-Smith sampler. Differences in sampler opening size and sampling time contribute to the measured differences, but the biggest effect is likely attributable to the bedload traps being mounted on ground plates thus avoiding direct contact between the sampler and the bed and preventing involuntary particle pick up.

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“…The same type of sampler was used to collect bedload at both sites. The Helley-Smith sampler has a high trapping efficiency for the predominant range of bedload moved in the two watersheds (Emmett, 1980) and has been used successfully to predict total bedload yield from other small mountain streams (Ryan and Porth, 1999). Bedload was sampled using the single equal width increment (SEWI) method (Edwards and Glysson, 1998), which involves placing the sampler at equally spaced positions (about 0.5 m apart) along a cross-sectional transect.…”

Section: Bedload Measurementsmentioning

confidence: 99%

“…Typically, there were too few data (4-12 observations) or the data were collected over too narrow a range of flow to permit the comparison of bedload models fit to annual data. In previous work, an assessment of the adequacy of sample size indicated that a minimum of 20 samples were required to define a relationship (Troendle et al, 1996) and between 60 and 80 samples were required to discriminate between means in groups of bedload samples on the order of 30%, for varying levels of power (Ryan and Porth, 1999). Since there were too few samples collected each year for this level of assessment, the observations from any one year were compared with data from all other years to determine if they fell outside of the 95% confidence limits of the predicted values (Fig.…”

Section: Annual and Seasonal Variation In Sediment Loadsmentioning

confidence: 99%

Gravel-Bed Rivers VI: From Process Understanding to River Restoration

Habersack

Piégay

Rinaldi

2007

Developments in Earth Surface Processes

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Sediment transport rates (dissolved, suspended, and bedload) measured over the course of several years are reported for two streams in the Gros Ventre Mountain range in western Wyoming, USA: Little Granite and Cache Creeks. Both streams drain watersheds that are in relatively pristine environments. The sites are about 20 km apart, have runoff dominated by snowmelt and are underlain by a similar geological setting, suggesting that sediment supply and rates of transport in the two watersheds may be comparable. Yet, estimated sediment yields for the two sites appear substantially different. On average, sediment load per unit watershed area was about 40% greater at Little Granite Creek than Cache Creek, with larger differences during wetter years. Moreover, while there were differences for all components of the sediment load, suspended, and bedload fractions showed the most noteworthy contrast where nearly three times more material was exported from Little Granite Creek on an annual basis. Speculatively, this is attributed to contributions of sediment from several chronic sources in the Little Granite Creek watershed.Similar to other studies of sediment transport in gravel-bed streams, the range of measured bedload and suspended sediment in this study were quite variable. An assessment of annual differences in the 13 years of bedload record for Little Granite Creek indicated that variability could not be ascribed to between-year differences. Instead, the data appear to represent the same population of highly variable transport rates. However, the inability to distinguish between years could be due to the infrequency with which data were collected each year. Seasonal variability was evident in the suspended sediment record of Little Granite Creek where there were higher rates on the rising limb of the snowmelt hydrograph, indicative of a flushing of sediment with the onset of snowmelt.Baseline data on rates of sediment transport provide useful information on the inherent variability of stream processes and may be used to assess departure due to natural or anthropogenic disturbances. In August 2000, wildfire burned portions of E-mail addresses: sryanburkett@fs.fed.us (S.E. Ryan) ISSN: 0928-2025 DOI: 10.1016/S0928-202511134-2 the Little Granite Creek watershed, presenting an opportunity to quantify increases in sediment loads associated with large-scale disturbance. The results of 3 years of postfire monitoring showed substantial increases in suspended sediment transport on the rising limb of the snowmelt hydrograph and during several summer thunderstorms. Suspended sediment yields calculated for the post-fire years were higher for the first year and have decreased over time, indicating a return to baseline levels within a few years following the wildfire. In contrast, there were no detectable increases in the rate of bedload transport over the pre-burn values suggesting differences in the rapidity with which the two sediment components respond to disturbance.

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A field comparison of three pressure-difference bedload samplers

Cited by 51 publications

References 21 publications

Coarse sediment transport in mountain streams in Colorado and Wyoming, USA

Coarse sediment transport in mountain streams in Colorado and Wyoming, USA

A Comparison of Coarse Bedload Transport Measured with Bedload Traps and Helley-Smith Samplers

Gravel-Bed Rivers VI: From Process Understanding to River Restoration

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