Publications associées à Gravier (granulat)

Stochastic Simulations and Machine Learning Modeling to Predict Bedload Transport and Bed Topography

In computational hydraulics models, predicting bed topography and bedload transport with sufficient accuracy remains a significant challenge. An accurate assessment of a river's sediment transport rate necessitates a prior understanding of its bed topograp ...

EPFL2024

Hydromorphological assessment of sediment augmentation measures in gravel-bed rivers

Christian Mörtl

In the riverine environment, the riverscape, sediment and flow regime are essential drivers for natural habitat dynamics. Today, most water courses in Europe are regulated, and their natural dynamics are impaired. Flood releases coupled with the artificial ...

EPFL2023

Dynamics of Dual-Mode Bedload Transport With Three-Dimensional Alternate Bars Migration in Subcritical Flow: Experiments and Model Analysis

Mehrdad Kiani Oshtorjani, Zhipeng Li, Yong Zhang

Bedload transport often exhibits dual-mode behavior due to interactions of spatiotemporal controlling factors with the migrating three-dimensional bedforms (characterized by the fully developed patterns in the bed, such as alternate bars, pools, and cluste ...

AMER GEOPHYSICAL UNION2023

Effects of water releases and sediment supply on a residual flow reach

Giovanni De Cesare, Robin Schroff, Camille Blanck

An artificial floods program has been implemented on the Sarine residual flow reach, downstream of the Rossens dam. Two artificial floods were released in 2016 (coupled with sediment augmentation) and in 2020. A natural flood occurred in 2021. The indicato ...

CRC Press/Balkema2023

Reduction of riverbed clogging related to sediment flushing

Giovanni De Cesare, Romain Maxime Dubuis

The ecological effects of dams on sediment and river flow have been subject to an increasing attention, leading to the implementation of mitigation measures such as environmental flow release and sediment replenishment. However, fine sediment dynamics have ...

CRC Press/Balkema2023

GALET: A deep learning image segmentation model for drone-based grain size analysis of gravel bars

Giovanni De Cesare, Christian Mörtl

In this study, we present the deep learning image segmentation model for drone-based grain size analysis of gravel bars called GALET. The objectives are to quantify the performance of the code and to test its applicability in river research and management. ...

International Association for Hydro-Environment Engineering and Research (IAHR)2022

Influence of depositional fabric on mechanical properties of naturally deposited sands

Gioacchino Viggiani, Edward Carlo Giorgio Andò

Fabric characteristics and shear deformation behaviour were analysed in four intact small-scale samples, including two disturbed and two undisturbed samples of naturally deposited sand from a shoal in the San Francisco Bay. Triaxial compression tests were ...

ICE PUBLISHING2022

Estimating Mean Bedload Transport Rates and Their Uncertainty

Christophe Ancey, Ivan Pascal

Measuring bedload transport rates usually involves measuring the flux of sediment or collecting sediment during a certain interval of time Δt. Because bedload transport rates exhibit significant non‐Gaussian fluctuations, their time‐averaged rates depend a ...

2020

Antidunes on steep slopes: variability of wave geometry and migration celerity

Christophe Ancey, Ivan Pascal

As a result of interactions between streamflow andsediment, riverbeds are seldom smooth, but depending onhydraulic and sediment transport conditions, they exhibitbedforms, which grow and migrate over time (upstreamor downstream). Morphology migration may e ...

Heide Friedrich and Karin Bryan2019

How bar generate sediment transport pulses in gravel-bed channels

Christophe Ancey, Ivan Pascal, Blaise Etienne Marceau Dhont

We ran flume experiments with constant water dis- charge and sediment feed rate at the inlet. Experi- ments were conducted over long times (typically 600 h). The bars migrated downstream intermittently, producing the most important pulses. When the bar pos ...

IAHR2018

Are Bedload Transport Pulses in Gravel Bed Rivers Created by Bar Migration or SedimentWaves?

Christophe Ancey, Blaise Etienne Marceau Dhont

Bedload transport exhibits considerable spatial and temporal variability, as reflected by large fluctuations of transport rates. Among the various mechanisms proposed for explaining this variability, bedform migration is often cited as the main cause. We t ...

2018

Bar dynamics and sediment transport pulses in gravel-bed channels

Christophe Ancey, Blaise Etienne Marceau Dhont

Mountain rivers exhibit sediment transport rate fluctuations that often cover more than two orders of magnitude. Bedform migration is often cited as the key process that causes giant fluctuations in the sediment transport rate. To quantify the effect of be ...

EDP Sciences2018

Design optimization of permeable sediment traps for fluvial bed load transport

Anton Schleiss, Sebastian Schwindt, Mona Jafarnejad Chaghooshi, Anita Hélène Roth

Sediment traps are crucial elements for flood protection in mountain rivers with high sediment transport capacity. Existing structures often interrupt the channel connectivity. Ideally, a sediment trap should be permeable for bed load during non-hazardous ...

2018

Sediment Pulses in a Gravel-Bed Flume with Alternate Bars

Blaise Etienne Marceau Dhont

The proper understanding of gravel-bed river dynamics is a crucial issue for the effective protection against related natural hazards, design of hydraulic structures, and preservation of their high ecological value in mountain regions. However, despite mor ...

EPFL2017

Wall-Roughness Effects on Flow and Scouring in Curved Channels with Gravel Beds

Anton Schleiss, Mário Jorge Rodrigues Pereira Da Franca

Due to a complex three-dimensional flow pattern, the outer banks of river bends are predisposed to erosion. When endangering civil structures, preventing measures to mitigate this erosion are thus required. Vertical ribs at protection walls for scour reduc ...

Asce-Amer Soc Civil Engineers2016

Entrainment,motion, and deposition of coarse particles transported by water over a sloping mobile bed

Christophe Ancey, Joris Heyman

In gravel bed rivers, bed load transport exhibits considerable variability in time and space. Recently, stochastic bed load transport theories have been developed to address the mechanisms and effects of bed load transport fluctuations. Stochastic models i ...

Wiley-Blackwell2016

Particle diffusion in non-equilibrium bedload transport simulations

Christophe Ancey

This paper examines the importance of particle diffusion relative to advection in bed load transport. Particle diffusion is not included in existing approaches to bedload transport. Based on recent advances in the probabilistic theory of sediment transport ...

Elsevier Science Inc2016

A parametrical study on secondary flow in sharp open-channel bends: experiments and theoretical modelling

Anton Schleiss, Koen Blanckaert, Joris Heyman

The dependence of curvature-induced secondary flow on the curvature ratio H/R (H is the average flow depth and R is the centreline radius of curvature), the Froude number Fr, and the dimensionless roughness coefficient Cf was systematically investigated in ...

Elsevier Science Bv2016

Hysteretic sediment fluxes in rainfall-driven soil erosion: Particle size effects

David Andrew Barry, Seifeddine Jomaa, Mohsen Cheraghi

A detailed laboratory study was conducted to examine the effects of particle size on hysteretic sediment transport under time-varying rainfall. A rainfall pattern composed of seven sequential stepwise varying rainfall intensities (30, 37.5, 45, 60, 45, 37. ...

American Geophysical Union2016

Detection and reconstruction of large-scale coherent flow structures in gravel-bed rivers

Ulrich Lemmin, Mário Jorge Rodrigues Pereira Da Franca

Large-scale flow structures (LSFS) in the streamwise direction are important features of gravel-bed river flows, because they may contribute to sediment transport and gas exchange. In the present study, these structures are detected using Huang's empirical ...

Wiley-Blackwell2015