A stability criterion inherent in laws governing alluvial channel flow

Huang, He Qing; Nanson, Gerald C.

doi:10.1002/esp.364

Cited by 64 publications

(59 citation statements)

References 66 publications

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“…These transport relations have very similar forms and can be expressed with the following equation (Huang and Nanson, 2002):…”

Section: Previous Conceptual Models For River Responsesmentioning

confidence: 98%

“…where q s is the bedload discharge per unit channel width, C s is a constant relating to sediment characteristics, τ o is the boundary shear stress, τ c is the critical shear stress for incipient motion, constants i = 0 and j = 1.5 for the Meyer-Peter and Müller relation (Meyer-Peter and Müller, 1948;Huang and Nanson, 2002), and constants i = j =1.0 for the Duboys relation (Duboys, 1879). For a given scenario, plotting Q s versus W/d per Eq.…”

Section: Previous Conceptual Models For River Responsesmentioning

confidence: 99%

“…(4) used by Huang and Nanson (2002) Reformulated per Wong and Parker (2006) Reformulated per Huang (2010) Curve A Curve C (35)) plotted as a function of width-to-depth ratio (W/d) for scenario. Q = 100 m 3 /s or cms, S = 0.0005, D s = 3 mm, n = 0.016, and z = 0.…”

Section: Qs (M 3 /S)mentioning

confidence: 99%

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Conceptual model for complex river responses using an expanded Lane's relation

Dust

Wohl

2012

Geomorphology

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“…These transport relations have very similar forms and can be expressed with the following equation (Huang and Nanson, 2002):…”

Section: Previous Conceptual Models For River Responsesmentioning

confidence: 98%

Section: Previous Conceptual Models For River Responsesmentioning

confidence: 99%

See 1 more Smart Citation

Conceptual model for complex river responses using an expanded Lane's relation

Dust

Wohl

2012

Geomorphology

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“…In contrast, minimizing the potential energy expenditure of the river by minimizing the slope for a given incision rate, and using a simple shear stress incision law, leads to predictions for the scaling of width, slope and discharge, and qualitatively good predictions for the dependence of channel geometry on incision rate and rock erodibility [ Lague et al , 2005a]. Such extremal hypotheses are a common approach in regime theory when treating alluvial river systems [e.g., Huang and Nanson , 2002; Eaton et al , 2004; Huang et al , 2004]. If the channel is in an energy configuration higher than the minimum, excess energy is expended to change channel shape.…”

Section: Channel Geometry At Steady Statementioning

confidence: 99%

Cover effect in bedrock abrasion: A new derivation and its implications for the modeling of bedrock channel morphology

Turowski¹,

Lague²,

Hovius³

2007

J. Geophys. Res.

214

434

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[1] The sediment load of a bedrock river plays an important role in the fluvial incision process by providing tools for abrasion (the tools effect) and by covering and thereby protecting the bed (the cover effect). We derive a new formulation for the cover effect, in which the fraction of exposed bed area falls exponentially with increasing sediment flux or decreasing transport capacity, and explore its consequences for the model of bedrock abrasion by saltating bed load. Erosion rates predicted by the model are higher than those predicted by earlier models. In a closed system, the maximum erosion rate is predicted to occur when sediment supply is equal to transport capacity for a flat bed. By optimizing the channel geometry to minimize the potential energy of the stream and using representative values for both discharge and grain size, we derive equations for the geometry of a bedrock river and explore how predictions for width, slope, and bed cover vary as functions of drainage area, rock uplift rate, and rock strength. The equations predict a dependence of channel width on drainage area similar to the relations using a simple shear stress incision law. The slope-area relationship is predicted to be concave up in a log-log regime, with a curvature dependent on uplift rate. However, this curvature does not deviate sufficiently from a straight line to allow discrimination between models using empirical data. Dependence of channel width and slope on rock uplift rate can be separated into two domains: for low uplift rates, channel geometry is largely insensitive to uplift rate due to a threshold effect. At high uplift rates, there is a power law dependence. Bed cover is predicted to increase progressively downstream and to increase with increasing uplift rate. In our model, the width-to-depth ratio is a function of both tectonic and climatic forcing. This indicates that the scaling between channel width and bed slope is neither a unique indicator of tectonic forcing at steady state nor a signature of transience or steady state. We conclude that sediment effects need to be taken into account when modeling bedrock channel morphology.Citation: Turowski, J. M., D. Lague, and N. Hovius (2007), Cover effect in bedrock abrasion: A new derivation and its implications for the modeling of bedrock channel morphology,

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“…The "minimum energy" condition has been described as a realisation of the variational principle of least action, which also corresponds to a situation of "maximum sediment transporting capacity", "minimum stream power" and "minimum friction" (Huang and Chang, 2006;Huang et al, 2004;Huang and Nanson, 2002;Nanson and Huang, 2008).…”

Section: Stagementioning

confidence: 99%

Dynamic modelling of coastal lagoon opening processes

Wainwright¹

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The coastline of south-eastern Australia contains a concentration of coastal lagoons which cyclically open and close to the ocean. Ocean waves act to build a barrier in front of the lagoon, isolating the lagoon from the ocean until such time as the barrier is breached, typically in response to catchment rainfall and barrier overtopping.In total, around 70 of these systems exist in New South Wales, with the majority south of Sydney.Similar systems also exist worldwide in places such as South Africa, California, New Zealand, Vietnam and Portugal to name several.A common management measure in New South Wales involves artificial breaching of the barrier when water levels in the lagoon become high enough to cause flooding concerns in surrounding low lying residential areas. With an expected rise in sea level, the viability of this management strategy is likely to decline. It is desirable to gain a better understand of entrance dynamics, including the breakout process. Numerical morphological models represent one way of improving that level of understanding.This thesis asserts that the coastal lagoon breaching process differs in key ways from the breaching of anthropogenic structures such as embankment dams, levee's and sea dikes. While the modelling of anthropogenic structures has received significant attention in the past, the breaching of coastal lagoons has been subject to comparatively less examination. By appreciating the differences, numerical morphological models can be better employed to represent the coastal lagoon breaching process.Perhaps foremost is the flatter slope and typically longer breach channel length of a coastal lagoon.While anthropogenic structures typically have relatively steep slopes (say ~ 1 in 5 to 1 in 3), the slope of the wave built barrier fronting coastal lagoons in New South Wales is commonly 1 in 10 or flatter on the ocean side, and significantly flatter again on the landward side. As the breach channel develops, it flattens even further and previous research indicates that the system settles into a highly efficient flow, characterised by near critical conditions (Froude No. ~ 1.0) including the development of standing wave bed forms and weak hydraulic jumps.The time for full breaching is typically longer O (~10hrs) than for anthropogenic structures O (~1hr) which also tend to have a more catastrophic impact when they breach. The increased time for coastal lagoon breaching also has important implications, for example, in the prediction of times required to relieve the effects of catchment flooding.Breaching is also significantly controlled by the rate at which the breach channel widens, and hence the geotechnical mechanisms controlling collapse of the side walls. Field and laboratory observations have repeatedly confirmed that the side walls of a sandy channel are near vertical during the breach. This presents some interesting challenges for numerical modelling.The research included the collection of a comprehensive set of field data during an artificial breach at Tabourie...

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A stability criterion inherent in laws governing alluvial channel flow

Cited by 64 publications

References 66 publications

Conceptual model for complex river responses using an expanded Lane's relation

Conceptual model for complex river responses using an expanded Lane's relation

Cover effect in bedrock abrasion: A new derivation and its implications for the modeling of bedrock channel morphology

Dynamic modelling of coastal lagoon opening processes

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