Spontaneous formation and degradation of pool-riffle morphology and sediment sorting using a simple fractional transport model

Gustavo Adolfo Mazza De Almeida, Jose Francisco Rodriguez

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Many gravel bed streams have a typical bed morphology consisting of pool-riffle sequences, which provides important habitat diversity both in terms of flow and substrate. A complete explanation of pool-riffle genesis and self-maintenance remains elusive and, despite advances in understanding the effects of flow spatial and temporal variability, the key sediment processes have been only marginally explored. Here we use a 1D unsteady multi-fraction morphodynamic model to explain the formation and degradation of pool-riffle sequences. Using a 1-year time series of measured flows below bankfull on a stream in which we have removed initial bedforms and sediment sorting our model spontaneously generates pools with finer substrate at narrow sections and riffles with coarser sediment at wider sections, closely resembling the natural bed morphology. Additional experiments show that under our modelling assumptions a variable flow regime is fundamental for development and self-maintenance of the longitudinal grain sorting characteristic of pool-riffle sequences, which could not be obtained or maintained with discharges held constant over relatively long periods. Copyright 2012 by the American Geophysical Union.
Original languageEnglish
JournalGeophysical Research Letters
Volume39
Issue number6
DOIs
Publication statusPublished - 2012
Externally publishedYes

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riffle
pool-riffle sequence
classifying
sorting
sediments
degradation
beds
sediment
maintenance
gravel bed stream
substrate
gravels
habitats
morphodynamics
bedform
time series
habitat
modeling
experiment

Cite this

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title = "Spontaneous formation and degradation of pool-riffle morphology and sediment sorting using a simple fractional transport model",
abstract = "Many gravel bed streams have a typical bed morphology consisting of pool-riffle sequences, which provides important habitat diversity both in terms of flow and substrate. A complete explanation of pool-riffle genesis and self-maintenance remains elusive and, despite advances in understanding the effects of flow spatial and temporal variability, the key sediment processes have been only marginally explored. Here we use a 1D unsteady multi-fraction morphodynamic model to explain the formation and degradation of pool-riffle sequences. Using a 1-year time series of measured flows below bankfull on a stream in which we have removed initial bedforms and sediment sorting our model spontaneously generates pools with finer substrate at narrow sections and riffles with coarser sediment at wider sections, closely resembling the natural bed morphology. Additional experiments show that under our modelling assumptions a variable flow regime is fundamental for development and self-maintenance of the longitudinal grain sorting characteristic of pool-riffle sequences, which could not be obtained or maintained with discharges held constant over relatively long periods. Copyright 2012 by the American Geophysical Union.",
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Spontaneous formation and degradation of pool-riffle morphology and sediment sorting using a simple fractional transport model. / De Almeida, Gustavo Adolfo Mazza; Rodriguez, Jose Francisco.

In: Geophysical Research Letters, Vol. 39, No. 6, 2012.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Spontaneous formation and degradation of pool-riffle morphology and sediment sorting using a simple fractional transport model

AU - De Almeida, Gustavo Adolfo Mazza

AU - Rodriguez, Jose Francisco

PY - 2012

Y1 - 2012

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AB - Many gravel bed streams have a typical bed morphology consisting of pool-riffle sequences, which provides important habitat diversity both in terms of flow and substrate. A complete explanation of pool-riffle genesis and self-maintenance remains elusive and, despite advances in understanding the effects of flow spatial and temporal variability, the key sediment processes have been only marginally explored. Here we use a 1D unsteady multi-fraction morphodynamic model to explain the formation and degradation of pool-riffle sequences. Using a 1-year time series of measured flows below bankfull on a stream in which we have removed initial bedforms and sediment sorting our model spontaneously generates pools with finer substrate at narrow sections and riffles with coarser sediment at wider sections, closely resembling the natural bed morphology. Additional experiments show that under our modelling assumptions a variable flow regime is fundamental for development and self-maintenance of the longitudinal grain sorting characteristic of pool-riffle sequences, which could not be obtained or maintained with discharges held constant over relatively long periods. Copyright 2012 by the American Geophysical Union.

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