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Temporal variability and memory in sediment transport in an experimental step-pool channel Saletti, Matteo; Molnar, Peter; Zimmermann, André; Hassan, Marwan A.; Church, Michael
Abstract
Temporal dynamics of sediment transport in steep channels using two experiments performed in a steep flume (8%) with natural sediment composed of 12 grain sizes are studied. High-resolution (1 s) time series of sediment transport were measured for individual grain-size classes at the outlet of the flume for different combinations of sediment input rates and flow discharges. Our aim in this paper is to quantify (a) the relation of discharge and sediment transport and (b) the nature and strength of memory in grainsize- dependent transport. None of the simple statistical descriptors of sediment transport (mean, extreme values, and quantiles) display a clear relation with water discharge, in fact a large variability between discharge and sediment transport is observed. Instantaneous transport rates have probability density functions with heavy tails. Bed load bursts have a coarser grain-size distribution than that of the entire experiment. We quantify the strength and nature of memory in sediment transport rates by estimating the Hurst exponent and the autocorrelation coefficient of the time series for different grain sizes. Our results show the presence of the Hurst phenomenon in transport rates, indicating long-term memory which is grain-size dependent. The short-term memory in coarse grain transport increases with temporal aggregation and this reveals the importance of the sampling duration of bed load transport rates in natural streams, especially for large fractions.
Item Metadata
Title |
Temporal variability and memory in sediment transport in an experimental step-pool channel
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Creator | |
Date Issued |
2015-11-28
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Description |
Temporal dynamics of sediment transport in steep channels using two experiments performed
in a steep flume (8%) with natural sediment composed of 12 grain sizes are studied. High-resolution (1 s)
time series of sediment transport were measured for individual grain-size classes at the outlet of the flume
for different combinations of sediment input rates and flow discharges. Our aim in this paper is to quantify
(a) the relation of discharge and sediment transport and (b) the nature and strength of memory in grainsize-
dependent transport. None of the simple statistical descriptors of sediment transport (mean, extreme
values, and quantiles) display a clear relation with water discharge, in fact a large variability between discharge
and sediment transport is observed. Instantaneous transport rates have probability density functions
with heavy tails. Bed load bursts have a coarser grain-size distribution than that of the entire experiment.
We quantify the strength and nature of memory in sediment transport rates by estimating the Hurst exponent
and the autocorrelation coefficient of the time series for different grain sizes. Our results show the
presence of the Hurst phenomenon in transport rates, indicating long-term memory which is grain-size
dependent. The short-term memory in coarse grain transport increases with temporal aggregation and this
reveals the importance of the sampling duration of bed load transport rates in natural streams, especially
for large fractions.
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Genre | |
Type | |
Language |
eng
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Date Available |
2017-01-31
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0308073
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URI | |
Affiliation | |
Citation |
Saletti M, Molnar P, Zimmermann A, Hassan MA, Church M. Temporal variability and memory in sediment transport in an experimental step-pool channel. Water Resour Res. 2015;51(11):9325-9337.
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Publisher DOI |
10.1002/2015WR016929
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Peer Review Status |
Reviewed
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Scholarly Level |
Faculty; Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International