The Effect Of Flow Depth On Sediment Transport Induced By Raindrops Impacting Shallow Flows

1991 ◽  
Vol 34 (1) ◽  
pp. 0161 ◽  
Author(s):  
P. I. A. Kinnell
Keyword(s):  
Sediment Transport ◽  
Flow Depth ◽  
Shallow Flows

Raindrop Size and Flow Depth Control Sediment Sorting in Shallow Flows on Steep Slopes

2018 ◽  
Vol 54 (12) ◽  
pp. 9978-9995 ◽  
Author(s):  
L. Wang ◽  
N. F. Fang ◽  
Z. J. Yue ◽  
Z. H. Shi ◽  
L. Hua
Keyword(s):  
Flow Depth ◽  
Control Sediment ◽  
Shallow Flows ◽  
Depth Control ◽  
Sediment Sorting ◽  
Raindrop Size ◽  
Steep Slopes

Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamicsThis paper is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007).

2009 ◽  
Vol 36 (10) ◽  
pp. 1605-1621 ◽  
Author(s):  
Rui M. L. Ferreira ◽  
Mário J. Franca ◽  
João G. A. B. Leal ◽  
António H. Cardoso
Keyword(s):  
Sediment Transport ◽  
Mathematical Modelling ◽  
Conceptual Models ◽  
Numerical Solutions ◽  
Shear Stresses ◽  
Shallow Flows ◽  
River Modelling ◽  
Morphologic Evolution ◽  
Sediment Mixtures ◽  
Selection Of

Mathematical modelling of river processes is, nowadays, a key element in river engineering and planning. River modelling tools should rest on conceptual models drawn from mechanics of sediment transport, river mechanics, and river hydrodynamics. The objectives of the present work are (i) to describe conceptual models of sediment transport, deduced from grain-scale mechanics of sediment transport and turbulent flow hydrodynamics, and (ii) to present solutions to specific river morphology problems. The conceptual models described are applicable to the morphologic evolution of rivers subjected to the transport of poorly sorted sediment mixtures at low shear stresses and to geomorphic flows featuring intense sediment transport at high shear stresses. In common, these applications share the fact that sediment transport and flow resistance depend, essentially, on grain-scale phenomena. The idealized flow structures are presented and discussed. Numerical solutions for equilibrium and nonequilibrium sediment transport are presented and compared with laboratory and field data.

scholarly journals Bedforms in a turbulent stream: ripples, chevrons and antidunes

2011 ◽  
Vol 690 ◽  
pp. 94-128 ◽  
Author(s):  
Bruno Andreotti ◽  
Philippe Claudin ◽  
Olivier Devauchelle ◽  
Orencio Durán ◽  
Antoine Fourrière
Keyword(s):  
Free Surface ◽  
Sediment Transport ◽  
Flow Direction ◽  
Linear Instability ◽  
Physical Parameters ◽  
Flow Depth ◽  
Supercritical Regime ◽  
Free Surface Waves ◽  
Alternate Bars ◽  
Flooding Events

AbstractThe interaction between a turbulent flow and a granular bed via sediment transport produces various bedforms associated with distinct hydrodynamical regimes. In this paper, we compare ripples (downstream-propagating transverse bedforms), chevrons and bars (bedforms inclined with respect to the flow direction) and antidunes (upstream-propagating bedforms), focusing on the mechanisms involved in the early stages of their formation. Performing the linear stability analysis of a flat bed, we study the asymptotic behaviours of the dispersion relation with respect to the physical parameters of the problem. In the subcritical regime (Froude number $\mathscr{F}$ smaller than unity), we show that the same instability produces ripples or chevrons depending on the influence of the free surface. The transition from transverse to inclined bedforms is controlled by the ratio of the saturation length ${L}_{\mathit{sat}} $, which encodes the stabilizing effect of sediment transport, to the flow depth $H$, which determines the hydrodynamical regime. These results suggest that alternate bars form in rivers during flooding events, when suspended load dominates over bedload. In the supercritical regime $\mathscr{F}\gt 1$, the transition from ripples to antidunes is also controlled by the ratio ${L}_{\mathit{sat}} / H$. Antidunes appear around resonant conditions for free surface waves, a situation for which the sediment transport saturation becomes destabilizing. This resonance turns out to be fundamentally different from the inviscid prediction. Their wavelength selected by linear instability mostly scales on the flow depth $H$, which is in agreement with existing experimental data. Our results also predict the emergence, at large Froude numbers, of ‘antichevrons’ or ‘antibars’, i.e. bedforms inclined with respect to the flow and propagating upstream.

Sediment Transport in Shallow Flows

1985 ◽  
Vol 111 (10) ◽  
pp. 1327-1342 ◽  
Author(s):  
Nadim M. Aziz ◽  
Shyam N. Prasad
Keyword(s):  
Sediment Transport ◽  
Shallow Flows

Sediment transport by shallow flows impacted by pulsed artificial rainfall

Soil Research ◽  
1993 ◽  
Vol 31 (2) ◽  
pp. 199 ◽  
Author(s):  
PIA Kinnell
Keyword(s):  
Sediment Transport ◽  
Soil Erosion ◽  
High Intensity ◽  
Influence Factors ◽  
High Energy ◽  
Sediment Discharge ◽  
Natural Conditions ◽  
Artificial Rainfall ◽  
Shallow Flows

In many experiments using rainfall simulators, rainfall is applied to the target as a high intensity pulse so that there are often long periods when the soil receives no rain and there are short periods when the soil receives rain at an extremely high intensity. Because concerns exist about the use of such methods of applying rain in experiments designed to help predict erosion under natural conditions, experiments using intermittent and continuous artificial rainfall were performed and analysed in terms of a recently developed theory on erosion by rain-impacted flow. The results indicate that the manner in which the rain is applied does not significantly influence the time-averaged sediment discharge from the sediment transport perspective. However, if high intensity, high energy pulses of rain influence factors which affect the susceptibility of the soil to erosion differently to continuous rain, then concerns about the use of intermittent rainfall in soil erosion experiments remain.

scholarly journals Modelling coupled hydraulics and sediment transport of a high-magnitude flood and associated landscape change

2007 ◽  
Vol 45 ◽  
pp. 143-154 ◽  
Author(s):  
Jonathan L. Carrivick
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Flow Velocity ◽  
Landscape Change ◽  
Flow Depth ◽  
Stream Power ◽  
Erosion And Deposition ◽  
High Magnitude ◽  
Outburst Floods ◽  
Load Transport

AbstractProcesses and mechanisms of erosion, transport and deposition within high-magnitude outburst floods such as jökulhlaups and lahars are poorly understood and remain largely unquantified. This study therefore applies a two-dimensional or depth-averaged hydrodynamic model, with fully integrated sediment transport, to reconstruct a Holocene jökulhlaup to have occurred from Kverkfjöll volcano, Iceland. Results indicate simultaneous inundation of multiple channels, flow around islands, hydraulic jumps and multi-directional flow including backwater areas and hydraulic ponding. These flow characteristics are typical of outburst floods that are volcanically triggered, flow through steep volcanic terrain and contain high concentrations of volcaniclastic sediment. Kverkfjöll jökulhlaups had low frontal flow velocities but as stage increased, velocities reached 5–15ms–1. Peak stage was prolonged in zones of hydraulic ponding, but generally attenuated in magnitude and duration downstream. Suspended load transport persisted over the entire hydrograph but bed load transport was spatially discontinuous and comprised distinct pulses. A hierarchy of landforms is proposed, ranging from highest energy zones (erosional gorges, scoured bedrock, cataracts and spillways) to lowest (valley-fills, bars and slackwater deposits). Bedrock erosion was generally where flow exceeded ∽3m flow depth, ∽7ms–1 flow velocity, ∽1×102Nm–2 shear stress and 3 ×102Wm–2 stream power. Deposition occurred below ∽8m flow depth, 11 ms–1 flow velocity, 5 ×102Nm–2 shear stress and 3 ×103Wm–2 stream power. Hydraulic ranges associated with erosion and deposition have considerable overlap due to transitional flow phenomena, transitions in sediment concentration and the influence of upstream effects, such as hydraulic ponding behind topographic constrictions. These results are the first of coupled hydraulic and sediment transport phenomena in high-magnitude outburst floods with fluid rheology and high sediment content, such as jökulhlaups and dilute lahars. Modelled changes in sediment mass closely resembled field-mapped zones of erosion and deposition. This paper therefore introduces a capability to simulate rapid landscape change due to high-magnitude outburst flood.

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