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Channel morphology and bedload pulses in braided rivers: a laboratory study
Author(s) -
Hoey Trevor B.,
Sutherland Alex J.
Publication year - 1991
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.3290160506
Subject(s) - bed load , aggradation , geology , streams , channel (broadcasting) , hyperconcentrated flow , geomorphology , hydrology (agriculture) , sediment , deposition (geology) , sediment transport , geotechnical engineering , fluvial , computer network , structural basin , computer science , engineering , electrical engineering
Bedload pulses in gravel‐bed rivers have been widely reported in recent years and attempts have been made to relate them to channel morphology. Bedload transport and channel morphology were measured in a small‐scale generic model of braided gravel‐bed streams. Two experiments are described in which braided channels developed in a 14 m × 3 m sand tray. Total bedload output from the tray was weighed every 15 minutes. Stream bed geometry was surveyed every four hours. Pulses were observed in the bedload output time series, and were qualitatively related to the channel morphology immediately upstream of the measuring section. The Bagnold (1980) bedload equation generally overpredicts measured bedload transport rates when applied to channels that were in equilibrium or aggrading. Underprediction occurred when applied to degrading channels. Aggradation was associated with channel multiplication and bar deposition. Channel pattern simplification occurred when degradation took place, and bars emerged from the water flow. Development of phases of aggradation and degradation is dependent upon the three‐dimensional geometry of the stream beds. Spatial and temporal feedback loops can be identified, enabling links between channel morphology and bedload transport rate to be directly identified.