Effect of flood hydrograph duration, magnitude, and shape on bed load transport dynamics

Phillips, C. B., Hill, K. M., Paola, C., Singer, M. B. ORCID: https://orcid.org/0000-0002-6899-2224 and Jerolmack, D. J. 2018. Effect of flood hydrograph duration, magnitude, and shape on bed load transport dynamics. Geophysical Research Letters 45 (16) , pp. 8264-8271. 10.1029/2018GL078976

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Abstract

Bed load sediment transport is an inherently challenging process to measure within a river, which is further complicated by the typically transient nature of the hydrograph. Here we use laboratory experiments to explore how sediment flux under transient—unsteady and intermittent—flow differ from those under steady flow. For a narrow unimodal sediment distribution, we calculated fluid stress and measured sediment flux for a range of hydrograph durations, magnitudes, shapes, and sequences. Within a hydrograph, we find considerable variability in sediment flux for a given stress above the threshold for motion. However, cumulative bed load flux resulting from a flood scales linearly with the integrated excess transport capacity (flow impulse). This scaling indicates that, to first order, flow magnitude, duration, shape, and sequence are only relevant to bed load flux in terms of their contribution to the total flow impulse, in agreement with prior field results. The flood impulse represents a quantitative parameter through which the effects of transient flow on coarse sediment transport may be parsed.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	American Geophysical Union (AGU)
ISSN:	0094-8276
Date of First Compliant Deposit:	14 November 2018
Date of Acceptance:	23 July 2018
Last Modified:	20 Nov 2024 00:00
URI:	https://orca.cardiff.ac.uk/id/eprint/114620

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