1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
Abstract : The Bayanbulak Grassland, Tianshan, China is located in an intramountane sedimentary basin where meandering and braided gravel-bed streams coexist under the same climatic and geological settings. We report on measurements of their discharge, width, depth, slope and grain size. Based on this data set, we compare the morphology of individual threads from braided and meandering streams. 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 streams. 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 streams. This suggests that a braided river is a collection of intertwined channels, which individually resemble isolated streams. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the channels to be wider than predicted by the threshold theory.
https://hal-insu.archives-ouvertes.fr/insu-03579369 Contributor : Nathalie PothierConnect in order to contact the contributor Submitted on : Friday, February 18, 2022 - 10:15:58 AM Last modification on : Thursday, March 17, 2022 - 10:08:29 AM Long-term archiving on: : Thursday, May 19, 2022 - 6:30:35 PM
F. Métivier, O. Devauchelle, H. Chauvet, E. Lajeunesse, P. Meunier, et al.. Morphology of meandering and braided gravel-bed streams from the Bayanbulak Grassland, Tianshan, China. Earth Surface Dynamics Discussions, 2015, 3, pp.1289-1316. ⟨10.5194/esurfd-3-1289-2015⟩. ⟨insu-03579369⟩