scholarly journals Paleoenvironment reconstructions and climate simulations of the Early Triassic: Impact of the water and sediment supply on the preservation of fluvial systems

2005 ◽  
Vol 18 (6) ◽  
pp. 431-446 ◽  
Author(s):  
Samuel Péron ◽  
Sylvie Bourquin ◽  
Frédéric Fluteau ◽  
François Guillocheau
Keyword(s):  
Sediment Supply ◽  
Early Triassic ◽  
Fluvial Systems ◽  
Water And Sediment ◽  
Climate Simulations

Sediment slugs: large-scale fluctuations in fluvial sediment transport rates and storage volumes

1995 ◽  
Vol 19 (4) ◽  
pp. 500-519 ◽  
Author(s):  
A.P. Nicholas ◽  
P.J. Ashworth ◽  
M.J. Kirkby ◽  
M.G. Macklin ◽  
T. Murray
Keyword(s):  
Sediment Transport ◽  
Sediment Supply ◽  
Fluvial Systems ◽  
Event Scale ◽  
Fluvial Sediment ◽  
Sediment Routing ◽  
Basin Scale ◽  
Wide Range ◽  
And Storage ◽  
Fluvial Sediment Transport

Variations in fluvial sediment transport rates and storage volumes have been described previously as sediment waves or pulses. These features have been identified over a wide range of temporal and spatial scales and have been categorized using existing bedform classifications. Here we describe the factors controlling the generation and propagation of what we term sediment slugs. These can be defined as bodies of clastic material associated with disequilibrium conditions in fluvial systems over time periods above the event scale. Slugs range in magnitude from unit bars (Smith, 1974) up to sedimentary features generated by basin-scale sediment supply disturbances (Trimble, 1981). At lower slug magnitudes, perturbations in sediment transport are generated by local riverbank and/or bed erosion. Larger-scale features result from the occurrence of rare high- magnitude geomorphic events, and the impacts on water and sediment production of tectonics, glaciation, climate change and anthropogenic influences. Simple sediment routing functions are presented which may be used to describe the propagation of sediment slugs in fluvial systems. Attention is drawn to components of the fluvial system where future research is urgently required to improve our quantitative understanding of drainage-basin sediment dynamics.

scholarly journals Efficacy of bedrock erosion by subglacial water flow

2015 ◽  
Vol 3 (3) ◽  
pp. 849-908 ◽  
Author(s):  
F. Beaud ◽  
G. E. Flowers ◽  
J. G. Venditti
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
Water Discharge ◽  
Sediment Supply ◽  
Fluvial Systems ◽  
Glacial Meltwater ◽  
Erosion Rates ◽  
Subglacial Environment ◽  
Basin Scale ◽  
Bedrock Erosion

Abstract. Bedrock erosion by sediment-bearing subglacial water remains little-studied, however the process is thought to contribute to bedrock erosion rates in glaciated landscapes and is implicated in the excavation of tunnel valleys and the incision of inner gorges. We adapt physics-based models of fluvial abrasion to the subglacial environment, assembling the first model designed to quantify bedrock erosion caused by transient subglacial water flow. The subglacial drainage model consists of a one-dimensional network of cavities dynamically coupled to one or several Röthlisberger channels (R-channels). The bedrock erosion model is based on the tools and cover effect, whereby particles entrained by the flow impact exposed bedrock. We explore the dependency of glacial meltwater erosion on the structure and magnitude of water input to the system, the ice geometry and the sediment supply. We find that erosion is not a function of water discharge alone, but also depends on channel size, water pressure and on sediment supply, as in fluvial systems. Modelled glacial meltwater erosion rates are one to two orders of magnitude lower than the expected rates of total glacial erosion required to produce the sediment supply rates we impose, suggesting that glacial meltwater erosion is negligible at the basin scale. Nevertheless, due to the extreme localization of glacial meltwater erosion (at the base of R-channels), this process can carve bedrock (Nye) channels. In fact, our simulations suggest that the incision of bedrock channels several centimetres deep and a few meters wide can occur in a single year. Modelled incision rates indicate that subglacial water flow can gradually carve a tunnel valley and enhance the relief or even initiate the carving of an inner gorge.

Deglacial changes in the strength of deep southern component water and sediment supply at the Argentine continental margin

2017 ◽  
Vol 32 (8) ◽  
pp. 796-812 ◽  
Author(s):  
Grit Warratz ◽  
Rüdiger Henrich ◽  
Ines Voigt ◽  
Cristiano M. Chiessi ◽  
Gerhard Kuhn ◽  
...  
Keyword(s):  
Continental Margin ◽  
Sediment Supply ◽  
Water And Sediment

Imprint of landscape dynamics in the luminescence signal of fluvial sediments (Rangitikei River, NZ)

2021 ◽  
Author(s):  
Anne Guyez ◽  
Stephane Bonnet ◽  
Tony Reimann ◽  
Sébastien Carretier ◽  
Jakob Wallinga
Keyword(s):  
Light Exposure ◽  
Experimental Testing ◽  
Landscape Dynamics ◽  
Sediment Supply ◽  
Fluvial Sediments ◽  
Fluvial Systems ◽  
The Earth ◽  
New Information ◽  
Landscape Response ◽  
Minimum Age

<p>Enlightenment of sediments pathways and storage patterns within river systems is critical to apprehend sediment transfer at the Earth’s surface and landscape response to tectonics and climate. Because direct tracing methods (painted, fluorescent or magnetic sediments) are of limited use in terms of their analytical resolution in time and space, alternative physico-chemical methods suitable for larger spatial-temporal scales have been developed (e.g. cosmogenic isotope, detrital thermochronology, isotopic geochemistry, etc). The study of the natural luminescence of sediment particles is emerging for this purpose and seems promising for providing new information complementary to existing methods. This method is based on the quartz/feldspar grains ability to store energy while buried below the Earth’s surface and to emit lumen with light exposure. Some recent studies have used this property to solve geomorphological questions regarding particle fluxes in soil or fluvial systems (Reimann et al., 2017; Sawakuchi et al., 2018) and to quantify rock exhumation (e.g. Herman et al., 2010). Here, we present an experimental testing of an innovative single-grain luminescence-based approach on feldspars. Focusing alongstream the Rangitikei River (RR), New Zealand, we carried out analysis on both modern sediment and Holocene terraces deposits.</p><p>We based our analysis on two complementarians proxies, the paleodose estimated using the bootstrapped minimum age model (Cunningham and Wallinga, 2012) and the percentage of grains eroded from bedrock and re-deposited in the river without signal resetting, i.e. saturated grains. We document changes in the luminescence signature of fluvial sediments while the RR evolves in response to uplift and climate change; from a late Pleistocene-early Holocene braided system to a Holocene incising canyon that subsequently widen.  This allows us to appraise temporal changes in the alongstream contribution of canyon flanks landsides to sediment supply to the river. Overall, we show that distinct landscape dynamics gives distinct luminescence signatures.</p>

Paleohydraulic investigation of the Ebro Basin: Implications for Mars

2021 ◽  
Author(s):  
Heath Geil-Haggerty
Keyword(s):  
Water Discharge ◽  
Sedimentary Basins ◽  
Mass Conservation ◽  
Sediment Supply ◽  
Sediment Flux ◽  
River Channels ◽  
Ebro Basin ◽  
Fluvial Systems ◽  
Sediment Size ◽  
Basin Scale

<p>The stratigraphy preserved in Earth’s sedimentary basins offers a record of how landscapes have evolved with time.  This stratigraphy provides insights into the dynamic processes that shaped the surface of the earth.  Fluvial stratigraphy contains many elements that can be used to recreate past conditions in ancient river channels.  Paleohydraulic reconstruction uses measurements of fluvial stratigraphy to model the conditions in the system that created them.  This allows us to answer questions related to water discharge, sediment flux, and duration of fluvial activity.  These are key questions when investigated in the context of Mars.  Paleohydraulic models can be used as compelling analogs for similar systems on Earth as well as Mars and other rocky planets.           </p><p>This study examines what the record of Oligocene-Miocene fluvial stratigraphy in northeastern Spain’s Ebro Basin can tell us about water discharge and sediment flux across distributive fluvial systems at a basin scale.  The Cenozoic stratigraphy of northeastern Spain’s triangular shaped Ebro Basin embodies a classic example of the formation of a closed sedimentary basin.  The Ebro Basin contains a number of remarkably well exposed fluvial sedimentary deposits.  These deposits outcrop as distinctive laterally contiguous channel sand bodies.  Clastic sediment supply in the Ebro Basin is largely governed by tectonic uplift and basin subsidence related to the Pyrenean orogen with peripheral contributions from the Catalan Coast and Iberian Ranges.  We test the idea that the record of conditions in the fluvial systems should reflect the record of lacustrine chemical sediments through sediment mass conservation.  In order to test this hypothesis measurements of bedform height, barform height, sediment size, and paleochannel dimensions were collected in the field.  Our paleohydraulic model uses previously derived theoretical and empirical relationships to recreate the conditions in these ancient fluvial systems.  These results are scaled up by accounting for drainage density and intermittency in order to address the principal question at a basin scale.  Paleodischarges from the fluvial sediments are comparable to those from river chemistry calculations for the lacustrine facies. </p>

scholarly journals Alluvial channel response to environmental perturbations: fill-terrace formation and sediment-signal disruption

2019 ◽  
Vol 7 (2) ◽  
pp. 609-631 ◽  
Author(s):  
Stefanie Tofelde ◽  
Sara Savi ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen
Keyword(s):  
Water Discharge ◽  
Sediment Supply ◽  
Fluvial Systems ◽  
Fluvial Terraces ◽  
Base Level ◽  
Environmental Perturbations ◽  
Alluvial Channel ◽  
Channel Slope ◽  
Lag Times ◽  
Sediment Export

Abstract. The sensitivity of fluvial systems to tectonic and climatic boundary conditions allows us to use the geomorphic and stratigraphic records as quantitative archives of past climatic and tectonic conditions. Thus, fluvial terraces that form on alluvial fans and floodplains as well as the rate of sediment export to oceanic and continental basins are commonly used to reconstruct paleoenvironments. However, we currently lack a systematic and quantitative understanding of the transient evolution of fluvial systems and their associated sediment storage and release in response to changes in base level, water input, and sediment input. Such knowledge is necessary to quantify past environmental change from terrace records or sedimentary deposits and to disentangle the multiple possible causes for terrace formation and sediment deposition. Here, we use a set of seven physical experiments to explore terrace formation and sediment export from a single, braided channel that is perturbed by changes in upstream water discharge or sediment supply, or through downstream base-level fall. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace cutting, and (3) the transient response of sediment export from the basin. In general, an increase in water discharge leads to near-instantaneous channel incision across the entire fluvial system and consequent local terrace cutting, thus preserving the initial channel slope on terrace surfaces, and it also produces a transient increase in sediment export from the system. In contrast, a decreased upstream sediment-supply rate may result in longer lag times before terrace cutting, leading to terrace slopes that differ from the initial channel slope, and also lagged responses in sediment export. Finally, downstream base-level fall triggers the upstream propagation of a diffuse knickzone, forming terraces with upstream-decreasing ages. The slope of terraces triggered by base-level fall mimics that of the newly adjusted active channel, whereas slopes of terraces triggered by a decrease in upstream sediment discharge or an increase in upstream water discharge are steeper compared to the new equilibrium channel. By combining fill-terrace records with constraints on sediment export, we can distinguish among environmental perturbations that would otherwise remain unresolved when using just one of these records.

scholarly journals Water and sediment supply affect basin-filling sedimentation patterns

Eos ◽  
2013 ◽  
Vol 94 (32) ◽  
pp. 288-288
Author(s):  
Ernie Balcerak
Keyword(s):  
Sediment Supply ◽  
Water And Sediment

scholarly journals FORMATIVE CONDITION OF BARS AND STREAMS WITH VEGETATION GROWTH UNDER UNSTEADY WATER AND SEDIMENT SUPPLY CONDITION

2006 ◽  
Vol 50 ◽  
pp. 973-978
Author(s):  
Hiroshi TAKEBAYASHI ◽  
Shinji EGASHIRA ◽  
Takeshi OKABE ◽  
Mitsuo TERAOKA
Keyword(s):  
Sediment Supply ◽  
Vegetation Growth ◽  
Water And Sediment ◽  
Supply Condition

scholarly journals Experimental Study on Flow and Sediment Distribution at Off-Take Channel

2021 ◽  
Vol 12 (2) ◽  
pp. 35-41
Author(s):  
Lamisa Malik ◽  
◽  
M. Abdul Matin
Keyword(s):  
Field Data ◽  
Physical Simulation ◽  
Low Flow ◽  
Sedimentation Pattern ◽  
Fluvial Systems ◽  
Sediment Distribution ◽  
Water And Sediment ◽  
Flow Visualizations ◽  
Complex Features ◽  
Distribution Of Flow

River off-take is one of the complex features in fluvial systems and the distribution of flow, and sediments along the branches are still a matter of research. This paper deals with a physical simulation on an off-take channel for understanding the flow and sediment distribution in the vicinity. Laboratory-based test runs have been carried out by changing the discharges and the angles off-take. A total of eighteen test runs have been conducted for three discharge conditions with three off-take angles. Two equations for predicting water and sediment discharge ratios have been proposed as a function of Froude number, channel geometry and off-take angel. Flow visualizations have also been carried out in the vicinity of the off-take for understanding erosion and sedimentation pattern. Flow and sediment movement patterns were carefully observed during the simulation and four distinguished zone formations have been noted in the vicinity. Finally, validations of the developed equations have been done with the field data from selected river off-take systems of Bangladesh. Validation results of field data show mean discrepancy ratios of 0.83 for the discharge equation and 0.89 for sediment equation during low flow.

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