Project

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Field measurements of sediment-flux-driven bedrock erosion

English title Field measurements of sediment-flux-driven bedrock erosion
Applicant Turowski Jens Martin
Number 132163
Funding scheme Project funding (Div. I-III)
Research institution Swiss Federal Research Inst. WSL Direktion
Institution of higher education Swiss Federal Institute for Forest, Snow and Landscape Research - WSL
Main discipline Geomorphology
Start/End 01.10.2010 - 31.03.2014
Approved amount 290'932.00
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All Disciplines (4)

Discipline
Geomorphology
Hydrology, Limnology, Glaciology
Other disciplines of Engineering Sciences
Geology

Keywords (8)

sediment transport; fluvial bedrock erosion; channel morphology; bedload transport; gornera; erlenbach; tools effect; cover effect

Lay Summary (English)

Lead
Lay summary
Bedrock channels are shaped by fluvial erosion, which at many sites is driven by the impact of moving sediment particles. So far, field studies of bedrock erosion have either ignored sediment effects, or used proxies and long-term sediment budgets to constrain transport rates. One of the reasons for this is that bedload transport rates are difficult to measure in the field, especially during the high-energy flows during which bedload transport occurs. In mountain rivers, predictions of sediment transport rates with conventional equations are highly inaccurate, often over-estimating observations by orders of magnitude. Laboratory investigations of the problem are limited, since high-energy flows and large-scale structures such as boulders and step-pool sequences are difficult to simulate accurately in a scaled experiment. Similar problems can be expected for laboratory investigations of fluvial bedrock erosion.The focus of the work will be on parallel measurements of fluvial erosion rates and sediment transport rates with cutting-edge methods in two study streams. At the streams selected for field work for this project, the Erlenbach and the Gornera, we have the unique opportunity to combine accurate field measurements of erosion with detailed knowledge of sediment transport rates. This will provide the first accurate field dataset with parallel measurements of sediment transport and erosion, and will allow the validation, calibration and improvement of existing bedrock erosion models on field data. A particular focus of the research will be the upscaling of local processes to larger areas, for example, a channel cross-section or reach.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
A demonstration of the importance of bedload transport for fluvial bedrock erosion and knickpoint propagation
Cook Kristen, Turowski Jens M., Hovius Niels (2013), A demonstration of the importance of bedload transport for fluvial bedrock erosion and knickpoint propagation, in Earth Surface Processes and Landforms, 38, 810-825.
Field measurements of the energy delivered to the channel bed by moving bedload and links to bedrock erosion
Turowski Jens M., Böckli Martin, Rickenmann Dieter, Beer Alexander R. (2013), Field measurements of the energy delivered to the channel bed by moving bedload and links to bedrock erosion, in Journal of Geophysical Research, Earth Surface, 118, 2438-2450.
Large floods, alluvial overprint and bedrock erosion in a steep mountain stream
Turowski Jens M., Badoux Alexandre, Leuzinger James, Hegglin Ramon (2013), Large floods, alluvial overprint and bedrock erosion in a steep mountain stream, in Earth Surface Processes and Landforms, 38, 947-958.
In situ measurement of bedrock erosion
Rieke-Zapp Dirk, Beer Alexander R., Turowski Jens M., Campana Lorenzo (2012), In situ measurement of bedrock erosion, in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences.

Collaboration

Group / person Country
Types of collaboration
Universität Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
National Taiwan University, Taipeh Taiwan (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Universität Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
University of California United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
- Exchange of personnel
Geoforschungsinstitut Potsdam Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Universität Nancy France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Grande Dixence SA Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
- Industry/business/other use-inspired collaboration
ETH Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
EMPA Switzerland (Europe)
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EGU General Assembly 2014 Poster Erosion model assessment using a high-resolution bedload-erosion dataset 27.04.2014 Wien, Austria Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2014 Poster High-resolution monitoring of fluvial bedrock erosion in a natural gorge 27.04.2014 Wien, Austria Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2014 Poster The influence of sediment thickness on energy delivery to the bed by bedload impacts 27.04.2014 Wien, Austria Turowski Jens Martin;
EGU General Assembly 2013 Poster High resolution structured light epoch scanning of natural bedrock erosion 07.04.2013 Wien, Austria Beer Alexander;
EGU General Assembly 2013 Poster Field measurements of the energy delivered to the channel bed by moving bedload 07.04.2013 Wien, Austria Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2013 Poster First insights in bedload impact forces causing bedrock abrasion 07.04.2013 Wien, Austria Turowski Jens Martin; Beer Alexander;
AGU Fall Meeting 2012 Poster A field experiment on the controls of sediment transport on bedrock erosion 03.12.2012 San Francisco, United States of America Beer Alexander;
Monitoring bedload and debris flows in mountain basins Poster Monitoring bedload pebbles in a mountain torrent with mobile and stationary RFID antennas 10.10.2012 Bozen, Italy Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2012 Poster Field measurements of bedrock erosion driven by bedload impacts 22.04.2012 Wien, Austria Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2012 Poster High resolution structured light epoch scanning of natural bedrock erosion 22.04.2012 Wien, Austria Beer Alexander;
EGU General Assembly 2012 Poster Large floods, alluvial overprint, and bedrock erosion 22.04.2012 Vienna, Austria Turowski Jens Martin;
Abschlusstagung - Wallis, Wasserkraft, Klimawandel Individual talk Einfluss des Klimawandels auf den Geschiebetransport 08.09.2011 Sion, Switzerland Turowski Jens Martin; Beer Alexander;
EGU General Assembly 2011 Poster Start and end of bedload transport in gravel-bed streams 03.04.2011 Vienna, Austria, Austria Turowski Jens Martin;


Associated projects

Number Title Start Funding scheme
124634 Sediment transport in steep streams 01.05.2009 Project funding (Div. I-III)
125975 SEDRIVER: Effects of sediment transporting flows on fish habitat in mountain rivers - expected development until 2050 taking into account climate change 01.04.2010 NRP 61 Sustainable Water Management

Abstract

Bedrock channels are shaped by fluvial erosion, which at many sites is driven by the impact of moving sediment particles (Tinkler and Wohl 1998). So far, field studies of bedrock erosion have either ignored sediment effects, or used proxies and long-term sediment budgets to constrain transport rates. One of the reasons for this is that bedload transport rates are difficult to measure in the field, especially during the high-energy flows in which bedload transport occurs. In mountain rivers, predictions of sediment transport rates with conventional equations are highly inaccurate, often over-estimating observations by orders of magnitude. Laboratory investigations of the problem are limited, since the high-energy flows and large-scale structures such as boulders and step-pool sequences are difficult to accurately simulate in a scaled experiment. It can be expected that laboratory investigations of fluvial bedrock erosion face similar problems.The aim of this project is to develop, test, validate, and calibrate published fluvial erosion laws such as the saltation-abrasion model with detailed field data of fluvial bedrock erosion and forcing parameters. The focus of the work will be on parallel measurements of fluvial erosion rates and sediment transport rates with cutting-edge methods in two study streams. In three tasks we will explore sediment-driven fluvial bedrock erosion on different scales and to different detail. Thereby, we will provide the first accurate, parallel field measurements of bedrock erosion rates and sediment transport rates.In Task A, the focus will be on the millimetre to centimetre scale. We will measure fluvial erosion rates on stone slabs to be installed in the experimental hydrologic catchment of the Erlenbach in the central Swiss pre-Alps. The stone slabs will be instrumented with force transducers and erosion sensors, which will be able to measure point erosion rates at high temporal resolution. In addition, the stones will be scanned regularly with sub-millimeter accuracy to obtain cumulative erosion rates from volume differences. Sediment transport has been monitored for more than 25 years at the Erlenbach, and more than 450 sediment transport events have been recorded. During the study period, we will monitor bedload transport by measuring deposition volumes in a retention basin, by conducting tracer studies within the catchment, by taking sediment samples with an automatic basket sampler system, and by using indirect sensors, which record a measurement every minute. With the obtained data we will calibrate and validate established process models of fluvial bedrock erosion such as the saltation-abrasion model.In Task B, we will concentrate on the influence of different grain sizes on bedrock erosion rates, and on the relative influence of suspended load versus bedload in particular. In the Gornera, a pro-glacial stream in the Matterhorn region in south-western Switzerland, water is collected for hydropower production, and the sediment load is separated by grain size in a series of four settling basins. The first basin holds back coarse gravel, the second fine gravel, and the remaining two sand and fines. The sediment is flushed out of the basins and re-inserted into the stream once a threshold volume has been deposited. Using high-resolution laser scanning, we will measure erosion rates at the outlet section of each flushing channel in natural bedrock to infer the influence of grain size on erosion.In Task C, we will investigate the distribution of erosion in the gorge of the Gornera downstream of the water intake, in relation to the distribution of stationary and moving alluvial sediments. Bedload transport occurs twice a day for about half an hour in the summer months during flushing operation in the first settling basin. Discharge is gauged and sediment volumes can be constrained by surveying the deposits in the basin. Using high-resolution laser scanning, we will accurately measure erosion rates in selected square-meter-sized plots. Reach and cross-sectional characteristics will be constrained with coarser resolution scans.The process model developed in Task A will be further tested and validated with the data from Tasks B and C. In particular, we will study in how far models developed for the process scale (Task A), can be upscaled to square-meter plots (Task B and C) and the channel cross-section or reach (Task C).
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