Bed Particle Displacements and Morphological Development in a Wandering Gravel‐Bed River

Abstract

Bed particles were tracked using passive integrated transponder tags in a wandering reach of the San Juan River, British Columbia, Canada, to assess particle movement around three major bars in the river. In‐channel topographic changes were monitored through repeat LiDAR surveys during this period and used in concert with the tracer data set to assess the relationship between particle displacements and changes in channel morphology, specifically, the development and re‐working of bars. This has direct implications for virtual velocity and morphologic based estimates of bedload flux, which rely on accurate estimates of the variability and magnitude of particle path lengths over time. Tracers were deployed in the river at three separate locations in the Fall of 2015, 2016, 2017, and 2018, with recovery surveys conducted during the summer low‐flow season the year after tracer deployment and multiple mobilizing events. Tracers exhibited path length distributions reflective of both morphologic controls and year to year differences related to the annual flow regime. Annual tracer transport was restricted primarily to less than one riffle‐pool‐bar unit, even during years with a greater number of peak floods and duration of competent flow. Tracer deposition and burial was focused along bar margins, particularly at or downstream of the bar apex, reflecting the downstream migration and lateral bar accretion observed on Digital Elevation Models of difference. This highlights the fundamental importance of bar development and re‐working underpinning bedload transport processes in bar‐dominated channels.

Flow Strength and Bedload Sediment Travel Distance in Gravel Bed Rivers

“…10.1029/2022WR032296 3 of 23 McQueen et al, 2021). To account for this effect, used variable morphologic lengths to collapse the relation between peak flow metrics and 𝐴𝐴 𝐿𝐿 .…”

Annual and decadal net morphological displacement of a small gravel‐bed channel

“…Probabilistic thresholds with confidence intervals of 95% (e.g., Brasington et al, 2000; Cucchiaro et al, 2019; James et al, 2020; Milan et al, 2007; Picco et al, 2013; Wheaton et al, 2013), 80% (e.g., Antoniazza et al, 2019; McQueen et al, 2020), and 68% (e.g., Cienciala & Hassan, 2013; Lane et al, 2003) have been used in past studies and were applied to the thresholded DoDs to determine significance using each as a level of detection (LoD). Three sets of new DoDs were then created with only the cells containing significant topographic changes, each set using a different LoD.…”

A multi-spatiotemporal scale strategy to evaluate factors controlling pebble mobility and its interactions with bedforms in a lowland gravel-bed river

“…Furthermore, the influence of bed morphology on travel distance, real or presumed, is more or less explicit in numerous studies (e.g., Beechie 2001;Hassan and Church, 1992;Hassan et al, 1991;Hassan and Bradley, 2017;Kasprak et al, 2015;Kondolf and Matthews, 1986;Lamarre and Roy, 2008;McDowell and Hassan, 2020;McDowell et al, 2021; This preprint research paper has not been peer reviewed. Electronic copy available at: https://ssrn.com/abstract=4151707 P r e p r i n t n o t p e e r r e v i e w e d McEwan, 2001;McQueen et al, 2021;Papangelakis and Hassan, 2016;Pyrce and Ashmore, 2003a, 2003bSchmidt and Gintz, 1995;Sear, 1996;.…”