Transport and storage of bed material in a gravel-bed channel during episodes of aggradation and degradation: a field and flume study
Article first published online: 29 SEP 2011
Published in 2011 by John Wiley and Sons, Ltd.
Earth Surface Processes and Landforms
Volume 36, Issue 15, pages 2028–2041, December 2011
How to Cite
Pryor, B. S., Lisle, T., Montoya, D. S. and Hilton, S. (2011), Transport and storage of bed material in a gravel-bed channel during episodes of aggradation and degradation: a field and flume study. Earth Surf. Process. Landforms, 36: 2028–2041. doi: 10.1002/esp.2224
- Issue published online: 1 DEC 2011
- Article first published online: 29 SEP 2011
- Accepted manuscript online: 31 AUG 2011 01:27AM EST
- Manuscript Accepted: 6 AUG 2011
- Manuscript Revised: 30 JUL 2011
- Manuscript Received: 3 DEC 2010
- bed material transport;
- sediment storage;
The dynamics of sediment transport capacity in gravel-bed rivers is critical to understanding the formation and preservation of fluvial landforms and formulating sediment-routing models in drainage systems. We examine transport-storage relations during cycles of aggradation and degradation by augmenting observations of three events of channel aggradation and degradation in Cuneo Creek, a steep (3%) gravel-bed channel in northern California, with measurements from a series of flume runs modeling those events. An armored, single-thread channel was formed before feed rates were increased in each aggradation run. Output rates increased as the channel became finer and later widened, steepened, and braided. After feed rates were cut, output rates remained high or increased in early stages of degradation as the incising channel remained fine-grained, and later decreased as armoring intensified. If equilibrium was not reached before sediment feed rate was cut, then a rapid transition from a braided channel to a single-thread channel caused output rates for a given storage volume to be higher during degradation than during aggradation. Variations in channel morphology, and surface bed texture during runs that modeled the three cycles of aggradation and degradation were similar to those observed in Cuneo Creek and provide confidence in interpretations of the history of change: Cuneo Creek aggraded rapidly as it widened, shallowed, and braided, then degraded rapidly before armoring stabilized the channel. Such morphology-driven changes in transport capacity may explain the formation of flood terraces in proximal channels. Transport-storage relations can be expected to vary between aggradation and degradation and be influenced by channel conditions at the onset of changes in sediment supply. Published in 2011. This article is a US Government work and is in the public domain in the USA.