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Concept

Charge de fond

Publications associées (25)

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

Mehrdad Kiani Oshtorjani

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

Influence of channel geomorphic units on bedload transport and river morphology during low‐magnitude bed‐forming floods coupled with sediment augmentation

Giovanni De Cesare, Severin Stähly, Christian Mörtl, Robin Schroff

In this study, we map different types of channel geomorphic units in a sediment-starved, residual-flow reach before and after an artificial flood. Bedload particles of a previous sediment augmentation measure are tracked with passive integrated transponder ...

2023

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

Mehrdad Kiani Oshtorjani

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

Scaling behavior of bedload transport: what if Bagnold was right?

Christophe Ancey

There is a paradox in the relationship between bedload transport rates and flow variables: laboratory and field studies have reported on how bedload transport rates depend on flow variables through a power law, but none of the empirical laws fitted to the ...

2023

The clogging of riverbeds: A review of the physical processes

Giovanni De Cesare, Romain Maxime Dubuis

Fine sediment represents an important part of the solid flux of rivers. Due to the size of these particles, they are often transported as suspended load. They gradually fill the pores of the substrate forming the hyporheic zone or cover the substrate by se ...

2023

Experimental Study on Bedload Transport and Bedforms: Behaviour and Interplay in Steep Turbulent Streams

Ivan Pascal

In mountain regions, steep streams play an important role in water and sediment connectivity. In these highly dynamic systems, water flow features, sediment fluxes and stream morphologies are tightly interlinked over a broad range of temporal and spatial s ...

EPFL2022

Bedload transport assessment on a physical model of a large river widening using ultrasonic Doppler velocity measurements

Giovanni De Cesare, Azin Amini, Jean-Noël Saugy

The 3rd correction of the Rhône River is the largest flood protection project in Switzerland so far. Covering a length of 162 km, it aims to protect some 100,000 people and prevent flood damages, which could raise up to 10 billion Swiss francs for major ev ...

ETH Zurich, Laboratory of Food Process Engineering2021

The variability of antidune morphodynamics on steep slopes

Christophe Ancey, Ivan Pascal

Steep streams on rough beds are generally characterised by supercritical flow conditions under which antidunes can develop and migrate over time. In this paper, we present flume experiments that we conducted to investigate the variability of antidune geome ...

2021

Bedload transport: a walk between randomness and determinism. Part 1. The state of the art

Christophe Ancey

This paper outlines the various approaches used to calculate bedload transport. As bedload transport exhibits considerable spatial and temporalvariations, computing the bedload transport rates and morphological changes experienced by streambeds is difficul ...

Taylor & Francis Ltd2020

Bedload transport: a walk between randomness and determinism. Part 2. Challenges and prospects

Christophe Ancey

By the late nineteenth century, the scientific study of bedload transport had emerged as an offshoot of hydraulics and geomorphology. Since then, computing bedload transport rates has attracted considerable attention, but whereas other environmental scienc ...

Taylor & Francis Ltd2020

Influence of collars on reduction in scour depth at two piers in a tandem configuration

Anton Schleiss, Giovanni De Cesare, Sargol Memar

Bridge failure, due to local scour at bridge pier foundations, has become a critical issue in river and bridge engineering, which might lead to transportation disruption, loss of lives and economic problems. A practical solution to prevent bridge collapses ...

SPRINGER INTERNATIONAL PUBLISHING AG2020

Modeling turbulent stream flows over rough permeable beds

Christophe Ancey, Ivan Pascal, Gauthier Paul Daniel Marie Rousseau

In steep streams, turbulent flows run over coarse sediments that are similar in size to flow depth. Under these conditions, a significant part of the flow may seep through the permeable bed. Based on experimental data, this paper presents a model able to r ...

CRC Press2020

Recent developments on management and release techniques of fine sediments in reservoirs

Anton Schleiss

Sedimentation is known as the process of filling up natural lakes and manmade reservoirs by sediment transforming finally into floodplaimns. Its main reason is the sediment yield transported by rivers as suspended or bed load into the reservoirs. Reservoir ...

2019

Potential erosion capacity of gravity currents created by changing initial conditions

Anton Schleiss, Mário Jorge Rodrigues Pereira Da Franca, Jessica Zordan

We investigate to what extent the initial conditions (in terms of buoyancy and geometry) of saline gravity currents flowing over a horizontal bottom influence their runout and entrainment capacity. In particular, to what extent the effect of the introducti ...

2019

The impact of hydrograph variability and frequency on sediment transport dynamics in a gravel-bed flume

Mário Jorge Rodrigues Pereira Da Franca, Carmelo Juez Jiménez

A laboratory study was undertaken to investigate how changes in flow regime and hydrograph shape (number of cycled hydrographs and duration of each hydrograph) together impact bedload transport and resulting bed morphology. Three hydrologic conditions (exp ...

WILEY2020

Preferential Deposition of Snow and Dust Over Hills: Governing Processes and Relevant Scales

Marc Parlange, Michael Lehning, Marco Giovanni Giometto, Francesco Comola

Preferential deposition of snow and dust over complex terrain is responsible for a wide range of environmental processes and accounts for a significant source of uncertainty in the surface mass balances of cold and arid regions. Despite the growing body of ...

2019

Turbulent Flows over Rough Permeable Beds in Mountain Rivers: Experimental Insights and Modeling

Gauthier Paul Daniel Marie Rousseau

Steep mountain streams exhibit shallow waters with roughness elements such as stones and pebbles that are comparable in size to flow depth. Owing to the difficulty in measuring fluid velocities at the interface, i.e., from the rough permeable bed to the fr ...

EPFL2019

The performance of collars on scour reduction at tandem piers aligned with different skew angles

Anton Schleiss, Giovanni De Cesare, Sargol Memar

Local scouring is a leading cause of bridge collapses. To protect bridges against local scouring, different countermeasures have been proposed and tested in the literature. In this study, the performance of collars was evaluated for scour reduction at two ...

2020

Upstream Erosion and Sediment Passage at Piano Key Weirs

Anton Schleiss, Michael Pfister, Ivan Stojnic

Piano key weirs (PKWs) are a weir type characterized by an effective rating curve. Accordingly, this control structure is primarily applied at dams to increase the spillway capacity. In recent years, PKWs also have been implemented in rivers combined with ...

2019

Stochastic bedload transport in mountain streams

Christophe Ancey

Describing bedload transport as a stochastic process is an idea that emerged in the 1930s with the pioneering work of Einstein. For a long time, the stochastic approach attracted marginal attention, but the situation has radically changed over the last dec ...

EDP Sciences2018