Preprints
https://doi.org/10.5194/esurf-2022-7
https://doi.org/10.5194/esurf-2022-7
 
09 Feb 2022
09 Feb 2022
Status: this preprint is currently under review for the journal ESurf.

Toward a general calibration of the Swiss plate geophone system for fractional bedload transport

Tobias Nicollier1,2, Gilles Antoniazza3,1, Lorenz Ammann1, Dieter Rickenmann1, and James W. Kirchner1,2,4 Tobias Nicollier et al.
  • 1Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
  • 2Deptartment of Environmental System Sciences, ETH Zürich, Zürich, 8092, Switzerland
  • 3Institute of Earth Surface Dynamics (IDYST), University of Lausanne, Lausanne, 1015, Switzerland
  • 4Deptartment of Earth and Planetary Science, University of California, Berkeley, 94720, USA

Abstract. Substantial uncertainties in bedload transport predictions in steep streams have triggered intensive efforts to develop surrogate monitoring technologies. One such system, the Swiss plate geophone (SPG), has been deployed and calibrated in numerous steep water courses, mainly in the Alps. Calibration relationships linking the signal recorded by the SPG system to the transported bedload can vary substantially between different monitoring stations, likely due to site-specific factors such as the flow velocity and the bed roughness. Furthermore, recent controlled experiments have shown that site-specific calibration relationships can be biased by elastic waves resulting from impacts occurring outside the plate boundaries. Motivated by these findings, here we present a hybrid calibration procedure derived from flume experiments and an extensive dataset of 308 calibration measurements from four different field monitoring stations. Our main goal is to investigate the feasibility of a general, site-independent calibration procedure for inferring fractional bedload transport from the SPG signal. First, we use flume experiments to show that sediment size classes can be distinguished more accurately using a combination of vibrational frequency and amplitude information than by using amplitude information alone. Second, we apply this amplitude-frequency method to field measurements to derive general calibration coefficients for ten different grain-size fractions. The amplitude-frequency method results in more homogeneous signal responses across all sites and significantly improves the accuracy of fractional sediment flux and grain-size estimates. We attribute the remaining site-to-site discrepancies to large differences in flow velocity, and discuss further factors that may influence the accuracy of these bedload estimates.

Tobias Nicollier et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2022-7', Anonymous Referee #1, 11 Mar 2022
  • RC2: 'Comment on esurf-2022-7', Dan Cadol, 16 Mar 2022
  • CC1: 'Comment on esurf-2022-7', Roger Kuhnle, 08 Apr 2022
    • RC3: 'Reply on CC1', Anonymous Referee #3, 27 Apr 2022

Tobias Nicollier et al.

Data sets

Field and Flume Claibration Datasets Tobias Nicollier, Gilles Antoniazza, Dieter Rickenmann https://www.envidat.ch/#/metadata/sediment-transport-observations-in-swiss-mountain-streams

Tobias Nicollier et al.

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Short summary
Monitoring sediment transport is relevant for flood safety and river restoration. However, the spatial and temporal variability of sediment transport processes make their prediction challenging. We investigate the feasibility of a general calibration relationship between sediment transport rates and the impact signals recorded by metal plates installed in the channel bed. We present a new calibration method based on flume experiments and apply it to an extensive dataset of field measurements.