Monitoring and modelling sediment transport processes in pool-riffle sequences
Monitoring and modelling sediment transport processes in pool-riffle sequences
This research couples sediment transport monitoring and the simulation of patterns of fluid flow in a natural pool-riffle sequence. Pool-riffle sequences are a mesoscale morphological characteristic of mixed grain size rivers that influence the transmission of water and sediment whilst providing valuable habitat. One aim of the current research is to increase our understanding of sediment-fluid interactions in pool-riffle sequences. This understanding is of benefit to environmental management issues related to river restoration, habitat diversity, water quality, flood prevention and bank erosion.
For this study the fluid dynamics in four natural, contiguous pool-riffle sequences are investigated using a three-dimensional computational fluid dynamics (CFD) model. The methods employed to simulate channel hydraulics and for designating the model boundary conditions are outlined and discussed. A series of experiments are used to assess sensitivity of model output to roughness characterisation and grid resolution. Model calculations are assessed using comparisons with field observations acquired over a range of flows. Simulations are used to illustrate flow structures and patterns of boundary shear stress for a near bankfull and an intermediate flow event. Simulated results suggest that near-bed velocities and bed shear stresses decrease on riffles and increase in pools as discharge increases. However, the magnitude of these trends is insufficient to cause a systematic reversal in any of the hydraulic variables. Model simulations show that secondary flow acts to route near-bed flow over the riffle-stoss and into the pool-head toward bars and away from the centre of pools, indicating pool maintenance by sediment bypassing.
University of Southampton
2000
Booker, Douglas James
(2000)
Monitoring and modelling sediment transport processes in pool-riffle sequences.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This research couples sediment transport monitoring and the simulation of patterns of fluid flow in a natural pool-riffle sequence. Pool-riffle sequences are a mesoscale morphological characteristic of mixed grain size rivers that influence the transmission of water and sediment whilst providing valuable habitat. One aim of the current research is to increase our understanding of sediment-fluid interactions in pool-riffle sequences. This understanding is of benefit to environmental management issues related to river restoration, habitat diversity, water quality, flood prevention and bank erosion.
For this study the fluid dynamics in four natural, contiguous pool-riffle sequences are investigated using a three-dimensional computational fluid dynamics (CFD) model. The methods employed to simulate channel hydraulics and for designating the model boundary conditions are outlined and discussed. A series of experiments are used to assess sensitivity of model output to roughness characterisation and grid resolution. Model calculations are assessed using comparisons with field observations acquired over a range of flows. Simulations are used to illustrate flow structures and patterns of boundary shear stress for a near bankfull and an intermediate flow event. Simulated results suggest that near-bed velocities and bed shear stresses decrease on riffles and increase in pools as discharge increases. However, the magnitude of these trends is insufficient to cause a systematic reversal in any of the hydraulic variables. Model simulations show that secondary flow acts to route near-bed flow over the riffle-stoss and into the pool-head toward bars and away from the centre of pools, indicating pool maintenance by sediment bypassing.
This record has no associated files available for download.
More information
Published date: 2000
Identifiers
Local EPrints ID: 464203
URI: http://eprints.soton.ac.uk/id/eprint/464203
PURE UUID: 01d62c55-524a-499d-8ee5-f1673c34c910
Catalogue record
Date deposited: 04 Jul 2022 21:33
Last modified: 04 Jul 2022 21:33
Export record
Contributors
Author:
Douglas James Booker
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics