Toward a general calibration of the Swiss plate geophone system for fractional bedload transport
<p>Substantial uncertainties in bedload transport predictions in steep streams have encouraged intensive efforts towards the development of surrogate monitoring technologies. One such system, the Swiss plate geophone (SPG), has been deployed and calibrated in numerous steep channels, mainly in...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2022-09-01
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Series: | Earth Surface Dynamics |
Online Access: | https://esurf.copernicus.org/articles/10/929/2022/esurf-10-929-2022.pdf |
Summary: | <p>Substantial uncertainties in bedload transport predictions in
steep streams have encouraged intensive efforts towards the development of
surrogate monitoring technologies. One such system, the Swiss plate geophone
(SPG), has been deployed and calibrated in numerous steep channels, mainly
in the Alps. Calibration relationships linking the signal recorded by the
SPG system to the intensity and characteristics of transported bedload can
vary substantially between different monitoring stations, likely due to
site-specific factors such as flow velocity and bed roughness. Furthermore,
recent flume experiments on the SPG system 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, we present a hybrid calibration procedure derived from flume
experiments and an extensive dataset of 308 direct field measurements at
four different SPG 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 10 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.</p> |
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ISSN: | 2196-6311 2196-632X |