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A new method for in‐situ measurement of the erosion threshold of river channels

Dunne, K. B. J. and Arratia, P. E. and Jerolmack, D. J. (2022) A new method for in‐situ measurement of the erosion threshold of river channels. Water Resources Research . ISSN 0043-1397. doi:10.1029/2022wr032407. (In Press)

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The vast majority of alluvial deposits have some degree of cohesion, typically due to the presence of clays and/or organic matter. Determining the threshold fluid shear stress, τ꜀, necessary to entrain these sediments is essential for predicting erosion rates and morphodynamics of rivers, tidal channels, and coasts. Cohesive sediments present a greater challenge than non-cohesive sand and gravel beds due to the sensitivity of τ꜀ to such factors as compaction, aggregation and particle surface chemistry. All of those factors may be altered if bed and bank sediments are extracted for later analysis in the laboratory. Environments with mixed cohesive and non-cohesive materials are common, such as sand-bedded rivers with muddy banks; it is therefore desirable to have a method for in-situ measurement of τ꜀ across a very wide range. We present a novel instrument that is capable of reproducibly determining τ꜀ for submerged cohesive and non-cohesive sediments in-situ. The instrument has several advantages over alternative methods, including ease of implementation in the field, and a fluid shear that is more representative of natural flows. The device incorporates common and low-cost components integrated with an Arduino micro-controller, which may receive commands from a mobile phone. We demonstrate our instrument’s capabilities in gravel, sand and clay-sand mixtures prepared in the laboratory, and present a proof-of-concept field deployment in a wadeable stream. Additionally, we provide the necessary schematics, parts lists, code and calibration procedures for the interested reader to build their own version of the instrument.

Item Type:Article
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URLURL TypeDescription Information ItemOperating code and data
Dunne, K. B. J.0000-0003-0995-7629
Arratia, P. E.0000-0002-2566-2663
Jerolmack, D. J.0000-0003-4358-6999
Additional Information:© 2022 American Geophysical Union. Accepted manuscript online: 17 August 2022. Manuscript accepted: 11 August 2022. Manuscript revised: 09 August 2022. Manuscript received: 19 March 2022. We thank Feifei Qian, Sonia Roberts, and Larry Galloway for their advice relating to the construction and wiring of the instrument. The research was sponsored by the Army Research Laboratory and was accomplished under grant number W911-NF-16-1-0290. Open Research: The parts list used for the prototype design and recommended Arduino pin assignments are available in Tables 1 and 2 of the Supplemental Material. Operating code and data used to detect the threshold of the various experimental substrates and in the field are available at this OSF data repository:
Funding AgencyGrant Number
Army Research LaboratoryW911-NF-16-1-0290
Record Number:CaltechAUTHORS:20220817-897502000
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Official Citation:Dunne, K. B. J., Arratia, P. E., & Jerolmack, D. J. (2022). A new method for in-situ measurement of the erosion threshold of river channels. Water Resources Research, 58, e2022WR032407.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116354
Deposited By: George Porter
Deposited On:17 Aug 2022 20:55
Last Modified:17 Aug 2022 20:55

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