Geometry of meandering and braided gravel-bed threads from the Bayanbulak Grassland, Tianshan, P. R. China

The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individu...

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Bibliographic Details
Published in:Earth surface dynamics 2016-01, Vol.4 (1), p.273-283
Main Authors: Métivier, François, Devauchelle, Olivier, Chauvet, Hugo, Lajeunesse, Eric, Meunier, Patrick, Blanckaert, Koen, Ashmore, Peter, Zhang, Zhi, Fan, Yuting, Liu, Youcun, Dong, Zhibao, Ye, Baisheng
Format: Article
Language:English
Subjects:
Bed load
Braided rivers
Braiding
Current meandering
Datasets
Depth
Discharge
Earth Sciences
Environmental conditions
Geometry
Geomorphology
Geophysics
Grain size
Grasslands
Gravel
Hydrologic data
Laboratories
Meandering
Morphology
River meanders
Rivers
Scaling
Scaling laws
Sciences of the Universe
Sediment transport
Sedimentary basins
Sediments
Statistical distributions
Statistics
Theories
Topography
Velocity
Width
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Summary:The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individual threads from these braided and meandering rivers. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed rivers. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering threads. This suggests that a braided river is a collection of intertwined threads, which individually resemble those of meandering rivers. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the threads to be wider than predicted by the threshold theory.
ISSN:2196-632X
2196-6311
2196-632X
DOI:10.5194/esurf-4-273-2016