Chapter 10 Maintenance of an obstruction-forced pool in a gravel-bed channel: streamflow, channel morphology, and sediment transport

2005 ◽  
pp. 169-196 ◽  
Author(s):  
Richard D. Woodsmith ◽  
Marwan A. Hassan
Keyword(s):  
Sediment Transport ◽  
Channel Morphology ◽  
Gravel Bed

scholarly journals Sediment transport at the network scale and its link to channel morphology in the braided Vjosa River system

2021 ◽  
Author(s):  
Simone Bizzi ◽  
Marco Tangi ◽  
Rafael J. P. Schmitt ◽  
John Pitlick ◽  
Hervé Piégay ◽  
...  
Keyword(s):  
Sediment Transport ◽  
River System ◽  
Channel Morphology ◽  
Network Scale

scholarly journals A reduced-complexity model for sediment transport and step-pool morphology

2016 ◽  
Author(s):  
Matteo Saletti ◽  
Peter Molnar ◽  
Marwan A. Hassan ◽  
Paolo Burlando
Keyword(s):  
Sediment Transport ◽  
Channel Morphology ◽  
Sediment Supply ◽  
Physically Based ◽  
Load Transport ◽  
Physically Based Models ◽  
Bed Load Transport ◽  
Transport Particle ◽  
Reduced Complexity ◽  
Complex Phenomena

Abstract. A new particle-based reduced-complexity model, CAST, to simulate sediment transport and channel morphology in steep streams is presented. CAST contains phenomenological parameterizations, deterministic or stochastic, of sediment supply, bed load transport, particle entrainment and deposition in a cellular-automaton space with uniform grain size. The model can reproduce a realistic bed morphology and typical fluctuations in transport rates observed in steep channels. Particle hop distances, from entrainment to deposition, are well-fitted by exponential distributions, in agreement with field data. The effect of stochasticity both in the entrainment and in the input rate is shown. A stochastic parameterization of the entrainment is essential to create and maintain a realistic channel morphology, while sediment transport in CAST shreds the input signal and its stochastic variability. A jamming routine has been added to CAST to simulate the grain-grain and grain-bed interactions that lead to particle jamming and step formation in a step-pool stream. The results show that jamming is effective in generating steps in unsteady conditions. Steps are created during high- flow periods and they survive during low flows only in sediment- starved conditions, in agreement with the jammed-state hypothesis of Church and Zimmermann (2007). Reduced-complexity models such as CAST can give new insight into the dynamics of complex phenomena (such as sediment transport and bedform stability) and be useful to test research hypotheses, being an effective complement to fully physically-based models.

scholarly journals Effect of stress history on sediment transport and channel adjustment in graded gravel-bed rivers

2021 ◽  
Author(s):  
Chenge An ◽  
Marwan A. Hassan ◽  
Carles Ferrer-Boix ◽  
Xudong Fu
Keyword(s):  
Sediment Transport ◽  
Critical Shear Stress ◽  
Transport Rate ◽  
Low Flow ◽  
Flood Event ◽  
Flume Experiments ◽  
Stress History ◽  
Gravel Bed ◽  
Sediment Transport Rate ◽  
Gravel Bed Rivers

<p>Recently, there has been an increasing attention on the environmental flow management for the maintenance of habitat diversity and ecosystem health of mountain gravel-bed rivers. More specifically, much interest has been paid to how inter-flood low flow can affect gravel-bed river morphodynamics during subsequent flood events. Such an effect is often termed as “stress history” effect. Previous research has found that antecedent conditioning flow can lead to an increase in the critical shear stress and a reduction in sediment transport rate during a subsequent flood. But how long this effect can last during the flood event has not been fully discussed. In this study, a series of flume experiments with various durations of conditioning flow are presented to study this problem. Results show that channel morphology adjusts significantly within the first 15 minutes of the conditioning flow, but becomes rather stable during the remainder of the conditioning flow. The implementation of conditioning flow can indeed lead to a reduction of sediment transport rate during the subsequent hydrograph, but such effect is limited only within a relatively short time at the beginning of the hydrograph. This indicates that bed reorganization during the conditioning phase, which induce the stress history effect, is likely to be erased with increasing intensity of flow and sediment transport during the subsequent flood event.</p>

scholarly journals Effect of stress history on sediment transport and channel adjustment in graded gravel-bed rivers

2020 ◽  
Author(s):  
Chenge An ◽  
Marwan A. Hassan ◽  
Carles Ferrer-Boix ◽  
Xudong Fu
Keyword(s):  
Sediment Transport ◽  
Critical Shear Stress ◽  
Transport Rate ◽  
Low Flow ◽  
Flood Event ◽  
Flume Experiments ◽  
Stress History ◽  
Gravel Bed ◽  
Sediment Transport Rate ◽  
Gravel Bed Rivers

Abstract. With the increasing attention on environmental flow management for the maintenance of habitat diversity and ecosystem health of mountain gravel-bed rivers, much interest has been paid to how inter-flood low flow can affect gravel-bed river morphodynamics during subsequent flood events. Previous research has found that antecedent conditioning flow can lead to an increase in the critical shear stress and a reduction in sediment transport rate during a subsequent flood. But how long this effect can last during the flood event has not been fully discussed. In this paper, a series of flume experiments with various durations of conditioning flow are presented to study this problem. Results show that channel morphology adjusts significantly within the first 15 minutes of the conditioning flow, but becomes rather stable during the remainder of the conditioning flow. The implementation of conditioning flow can indeed lead to a reduction of sediment transport rate during the subsequent hydrograph, but such effect is limited only within a relatively short time at the beginning of the hydrograph. This indicates that bed reorganization during the conditioning phase, which induce the stress history effect, is likely to be erased with increasing intensity of flow and sediment transport during the subsequent flood event.

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