Multimode Morphodynamic Model for Sediment-Laden Flows and Geomorphic Impacts

Guan, Mingfu; Wright, Nigel; Sleigh, Andrew

doi:10.1061/(asce)hy.1943-7900.0000997

Cited by 28 publications

(23 citation statements)

References 35 publications

(40 reference statements)

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“…where F i , percentage of the i th grain fraction; ω f,i , effective settling velocity for the i th grain fraction which is calculated by using the formula derived by Soulsby ():

ω_{f, i} = \frac{ν}{d_{i}} ([], \sqrt{{10.36}^{2} + {(1 - C)}^{4.7} 1.049 d_{*, i}^{3}} - 10.36)

italicwhere d_{*, i} = d_{i} {[\frac{g ((), s - 1)}{ν^{2}}]}^{1 false/ 3}

; C a,i = δC i is the near‐bed concentration for the i th grain fraction at the reference level a ; the definition of the coefficient δ is: δ = min{2.0, (1. p)/ C }; C ae,i is the near‐bed equilibrium concentration at the reference level that is calculated by using the van Rijin's formula (van Rijin ; Guan et al . ).…”

Section: Methodsmentioning

confidence: 97%

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The influence of floodplain restoration on flow and sediment dynamics in an urban river

Ahilan

Guan

Sleigh

et al. 2016

J Flood Risk Management

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A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two‐dimensional hydro‐morphodynamic model for predicting flow and suspended‐sediment dynamics in the downstream of Johnson Creek, the East Lents reach, where the bank of the river has been reconfigured to reconnect to a restored floodplain on a 0.26 km2 (26‐ha) site. The simulation scenarios include 10‐, 50‐, 100‐ and 500‐year event‐based deposition modelling of flood events and long‐term modelling using the 64 historical flood events between 1941 and 2014. Simulation results showed that the restored floodplain significantly attenuates the upstream flood peak by up to 25% at the downstream. Results also indicated that approximately 20%–30% of sediment from the upstream is deposited on the East Lents floodplain. Furthermore, deposited sediment over the simulated period (1941–2014) is approximately 0.1% of the basin's flood storage capacity; however, the reduction in the storage does not offset the overall flood resilience impact of the flood basin. The sediment conservation at the East Lents flood basin as predicted by the model reduces the annual sediment loading of the Johnson Creek by 1% at the confluence with Willamette River, providing both improved water quality and flood resilience further downstream.

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“…where F i , percentage of the i th grain fraction; ω f,i , effective settling velocity for the i th grain fraction which is calculated by using the formula derived by Soulsby ():

ω_{f, i} = \frac{ν}{d_{i}} ([], \sqrt{{10.36}^{2} + {(1 - C)}^{4.7} 1.049 d_{*, i}^{3}} - 10.36)

italicwhere d_{*, i} = d_{i} {[\frac{g ((), s - 1)}{ν^{2}}]}^{1 false/ 3}

Section: Methodsmentioning

confidence: 97%

“…; C a,i = δC i is the near-bed concentration for the ith grain fraction at the reference level a; the definition of the coefficient δ is: δ = min{2.0, (1. p)/C}; C ae,i is the near-bed equilibrium concentration at the reference level that is calculated by using the van Rijin's formula (van Rijin 1984;Guan et al 2015a).…”

Section: Suspended Sediment Load Modelmentioning

confidence: 99%

The influence of floodplain restoration on flow and sediment dynamics in an urban river

Ahilan

Guan

Sleigh

et al. 2016

J Flood Risk Management

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“…Morphological changes commonly occur with flows in natural systems over period of time and changes are more produced during floods. In recent years, increasing attention has been paid to numerical modeling of river hydrodynamics and morphodynamics, and a large number of computational models have been developed [ Abad et al ., ; Guan et al ., ; Li and Duffy , ; Wu , ]. However, in contrast to straight channels, channel bends demonstrate much more complex flow features due to the presence of helical (secondary) flows [ Blanckaert , ; De Vriend , ; Johannesson and Parker , ; Odgaard , ; Song et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Physical complexity to model morphological changes at a natural channel bend

Guan

Wright

Sleigh

et al. 2016

Water Resources Research

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This study developed a two‐dimensional (2‐D) depth‐averaged model for morphological changes at natural bends by including a secondary flow correction. The model was tested in two laboratory‐scale events. A field study was further adopted to demonstrate the capability of the model in predicting bed deformation at natural bends. Further, a series of scenarios with different setups of sediment‐related parameters were tested to explore the possibility of a 2‐D model to simulate morphological changes at a natural bend, and to investigate how much physical complexity is needed for reliable modeling. The results suggest that a 2‐D depth‐averaged model can reconstruct the hydrodynamic and morphological features at a bend reasonably provided that the model addresses a secondary flow correction, and reasonably parameterize grain‐sizes within a channel in a pragmatic way. The factors, such as sediment transport formula and roughness height, have relatively less significance on the bed change pattern at a bend. The study reveals that the secondary flow effect and grain‐size parameterization should be given a first priority among other parameters when modeling bed deformation at a natural bend using a 2‐D model.

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“…Previous studies on other types of outburst floods unequivocally demonstrate that inclusion of sediment transport and morphodynamics in modelling of the flow is important because: (i) outburst floods often undergo 'bulking' and 'dilution' due to rapid sediment entrainment and deposition, respectively (Lube et al ., ); (ii) entrained sediment affects the mass and momentum energy of a flow (Fraccarollo and Capart, ; Zech et al ., ; Carrivick, ; Carrivick et al ., ; Iverson et al ., ; Guan et al ., , ); (iii) erosion and deposition changes channel geometry, on occasion by over 100% in a few min (Carrivick et al ., ), and crucially these three individually and in combination feed back to perturb hydraulics (Guan et al ., , ). Furthermore, (iv) sediment transported in a flow can constitute the major hazard associated with outburst floods, impacting structures and burying property, for example.…”

Section: Introductionmentioning

confidence: 99%

Geomorphological impact and morphodynamic effects on flow conveyance of the 1999 jökulhlaup at sólheimajökull, Iceland

Staines

Carrivick

2015

Earth Surf Processes Landf

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9The 1999 jökulhlaup at Sólheimajökull was the first major flood to be routed through the proglacial system in 10 over 600 years. This study reconstructed the flood using hydrodynamic, sediment transport and morphodynamic 11 numerical modelling informed by field surveys, aerial photograph and digital elevation model analysis. advanced flood arrival and peak discharge timings by 100 % and 19 %, respectively. However, peak flow depth 22 and peak flow velocity were not significantly affected. We suggest that morphodynamic processes not only 23 increase flow mass and momentum but that they also introduce a feedback process whereby flood conveyance 24 becomes more efficient via erosion of minor bed protrusions and deposition that infills or subdues minor bed 25 hollows. A major implication of this study is that reconstructions of outburst floods that ignore sediment 26 transport, such as those used in interpretation of long term hydrological record and flood risk assessments, may 27 need considerable refinement. 28

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Multimode Morphodynamic Model for Sediment-Laden Flows and Geomorphic Impacts

Cited by 28 publications

References 35 publications

The influence of floodplain restoration on flow and sediment dynamics in an urban river

The influence of floodplain restoration on flow and sediment dynamics in an urban river

Physical complexity to model morphological changes at a natural channel bend

Geomorphological impact and morphodynamic effects on flow conveyance of the 1999 jökulhlaup at sólheimajökull, Iceland

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