Calibration of acoustic doppler current profiler apparent bedload velocity to bedload transport rate

Rennie, C. D., Vericat, D., Williams, R. D. , Brasington, J. and Hicks, M. (2017) Calibration of acoustic doppler current profiler apparent bedload velocity to bedload transport rate. In: Tsutsumi, D. and Laronne, J. B. (eds.) Gravel-Bed Rivers: Process and Disasters. John Wiley & Sons: Chichester, pp. 209-233. ISBN 9781118971406 (doi:10.1002/9781118971437.ch8)

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Abstract

The bias in aDcp bottom tracking induced by near-bed particle motion provides a measure of apparent bedload velocity (va ). Previous site specific field and laboratory calibration exercises to relate bedload transport rate (gb ) to va are reviewed. Good linear relations have been obtained, with r2 ranging from 0.30 to 0.91. The calibration relations differ as a function of both bed material and aDcp operating parameters. In general, for a given value of va , higher mass transport is observed in gravel-bed rivers than sand-bed rivers. The influence of bedload grain size is evaluated in detail using a new data set of 144 paired va and gb samples obtained at the braided gravel-bed Rees River, New Zealand. The bed material of the Rees River includes both sand and gravel, with subsurface median (D50) grain size of 7.5 mm, and the D50 of collected bedload samples ranging from 0.2 mm to 13 mm. Relatively poor gb-va correlation was observed for the entire Rees River data set (r2 = 0.29). However, excluding samples with <69% good bottom track data and classifying the remaining samples into subpopulations by bedload grain size (sand, sand with > 10% gravel, gravel with > 10% sand, and gravel) improved gb-va calibration relations (r2 ranging from 0.45 to 0.98). The implications for utilization of such size-dependent gb-va calibration relations in rivers with mixed gravel-sand beds are discussed.

Item Type:Book Sections
Status:Published
Glasgow Author(s) Enlighten ID:Williams, Dr Richard
Authors: Rennie, C. D., Vericat, D., Williams, R. D., Brasington, J., and Hicks, M.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Publisher:John Wiley & Sons
ISBN:9781118971406
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