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Understanding pool-riffle dynamics through continuous morphological simulations

Understanding pool-riffle dynamics through continuous morphological simulations
Understanding pool-riffle dynamics through continuous morphological simulations
Pool-riffle dynamics is governed by complex time and spatial interactions between water and sediment flows. In the last few decades, significant advances have been made in characterizing and modeling the hydrodynamics of pool-riffle sequences, and this information has been extensively used as the basis of conceptual models to describe or infer pool-riffle morphodynamics. A lot less attention, however, has been paid to the coupled dynamics of flow and sediment, which is essential to fully understand these complex geomorphic systems. This paper uses an unsteady 1-D flow-morphology and bed-sorting model to analyze pool-riffle dynamics. The model is first applied to a pool-riffle sequence on a 1.1 km reach of the lower Bear Creek, Arkansas, United States. After showing the model's ability to describe the general reach hydrodynamics and morphological evolution over 1 year, the detailed sediment and flow information is used to investigate pool-riffle dynamics in terms of self-maintenance mechanisms. Two effects that have been only marginally explored in the past, i.e., bed sediment sorting and downstream riffle control, are explained and quantified with the help of the model's outputs. The results show that self-maintenance occurs more frequently than previously thought as a result of grain sorting and that erosion or deposition of contiguous riffles also constitutes a self-maintenance mechanism. These findings provide the support for a physically based, integral description of pool-riffle morphodynamics and highlight the importance of flow and sediment variability on pool-riffle self-maintenance. The morphodynamic analysis bridges the gap between observations and current theories based mainly on hydrodynamic information.
pool, riffle, 1-D model, morphology, morphodynamics, sediment transport
0043-1397
W01502-[15pp]
de Almeida, Gustavo A. M.
f6edffc1-7bb3-443f-8829-e471b6514a7e
Rodriguez, Jose F.
7d2ce7e6-c404-45da-9a89-5ced480e2039
de Almeida, Gustavo A. M.
f6edffc1-7bb3-443f-8829-e471b6514a7e
Rodriguez, Jose F.
7d2ce7e6-c404-45da-9a89-5ced480e2039

de Almeida, Gustavo A. M. and Rodriguez, Jose F. (2011) Understanding pool-riffle dynamics through continuous morphological simulations. Water Resources Research, 47 (1), W01502-[15pp]. (doi:10.1029/2010WR009170).

Record type: Article

Abstract

Pool-riffle dynamics is governed by complex time and spatial interactions between water and sediment flows. In the last few decades, significant advances have been made in characterizing and modeling the hydrodynamics of pool-riffle sequences, and this information has been extensively used as the basis of conceptual models to describe or infer pool-riffle morphodynamics. A lot less attention, however, has been paid to the coupled dynamics of flow and sediment, which is essential to fully understand these complex geomorphic systems. This paper uses an unsteady 1-D flow-morphology and bed-sorting model to analyze pool-riffle dynamics. The model is first applied to a pool-riffle sequence on a 1.1 km reach of the lower Bear Creek, Arkansas, United States. After showing the model's ability to describe the general reach hydrodynamics and morphological evolution over 1 year, the detailed sediment and flow information is used to investigate pool-riffle dynamics in terms of self-maintenance mechanisms. Two effects that have been only marginally explored in the past, i.e., bed sediment sorting and downstream riffle control, are explained and quantified with the help of the model's outputs. The results show that self-maintenance occurs more frequently than previously thought as a result of grain sorting and that erosion or deposition of contiguous riffles also constitutes a self-maintenance mechanism. These findings provide the support for a physically based, integral description of pool-riffle morphodynamics and highlight the importance of flow and sediment variability on pool-riffle self-maintenance. The morphodynamic analysis bridges the gap between observations and current theories based mainly on hydrodynamic information.

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Published date: January 2011
Keywords: pool, riffle, 1-D model, morphology, morphodynamics, sediment transport
Organisations: Water & Environmental Engineering Group

Identifiers

Local EPrints ID: 356383
URI: http://eprints.soton.ac.uk/id/eprint/356383
ISSN: 0043-1397
PURE UUID: f8d62d0a-6d49-4cd7-af38-eaf9189570e3
ORCID for Gustavo A. M. de Almeida: ORCID iD orcid.org/0000-0002-3291-3985

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Date deposited: 10 Sep 2013 13:08
Last modified: 15 Mar 2024 03:48

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Author: Jose F. Rodriguez

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