TY - JOUR
T1 - The Advective-Diffusive Morphodynamics of Mixed Bedrock-Alluvial Rivers Subjected to Spatiotemporally Varying Sediment Supply
AU - Zhang, Li
AU - Stark, Colin
AU - Schumer, Rina
AU - Kwang, Jeffrey
AU - Li, Tiejian
AU - Fu, Xudong
AU - Wang, Guangqian
AU - Parker, Gary
N1 - Funding Information:
The participation of Parker and Stark was made possible in part by a grant from the U.S. National Science Foundation (EAR-1124482). The participation of Parker was also made possible in part by the National Center for Earth-surface Dynamics, a Science and Technology Center funded by the U.S. National Science Foundation (EAR- 0120914). This paper is supported by National Natural Science Foundation of China 51569026. The code of MRSAA-c model is available at https://github. com/csdms-contrib/MRSAA. All the data in this paper are shown in the support ing information. John Buffington, Mikaël Attal, and three anonymous reviewers greatly strengthened this paper.
PY - 2018/8
Y1 - 2018/8
N2 - Mountain rivers subject to earthquakes and intense precipitation have highly variable sediment supply rates. Here we consider the morphodynamics of 1-D mixed bedrock-alluvial rivers with temporally varying sediment supply rates. We use a periodic sedimentograph, characterized by short periods of high sediment feed rate and longer periods of low sediment feed rate. We study the problem with a corrected Macroroughness Saltation-Abrasion-Alluviation model. In this model, incision is driven by bedload colliding with bedrock, but incision can be turned off by either zero sediment transport or complete alluviation. The formulation is advective-diffusive, the former capturing upstream-migrating knickpoints and the latter capturing smearing of the sedimentograph downstream. The steady state balance between incision and uplift is characterized by a bedrock slope that varies downstream, exhibiting low values at the upstream end of the domain and higher values farther downstream. Sufficiently far downstream, the bedrock slope approaches that predicted for constant feed rates. The zone of low slope near the feed point corresponds to a pocket (zone of locally depressed bedrock slope) in the longitudinal profile, which is repeatedly drowned in and flushed of sediment. The steady state slope profile of a shorter reach is a truncated version of that of a longer reach. A limiting reach length including the pocket defines a sedimentograph boundary layer, where the effects of sediment feed fluctuation are felt.
AB - Mountain rivers subject to earthquakes and intense precipitation have highly variable sediment supply rates. Here we consider the morphodynamics of 1-D mixed bedrock-alluvial rivers with temporally varying sediment supply rates. We use a periodic sedimentograph, characterized by short periods of high sediment feed rate and longer periods of low sediment feed rate. We study the problem with a corrected Macroroughness Saltation-Abrasion-Alluviation model. In this model, incision is driven by bedload colliding with bedrock, but incision can be turned off by either zero sediment transport or complete alluviation. The formulation is advective-diffusive, the former capturing upstream-migrating knickpoints and the latter capturing smearing of the sedimentograph downstream. The steady state balance between incision and uplift is characterized by a bedrock slope that varies downstream, exhibiting low values at the upstream end of the domain and higher values farther downstream. Sufficiently far downstream, the bedrock slope approaches that predicted for constant feed rates. The zone of low slope near the feed point corresponds to a pocket (zone of locally depressed bedrock slope) in the longitudinal profile, which is repeatedly drowned in and flushed of sediment. The steady state slope profile of a shorter reach is a truncated version of that of a longer reach. A limiting reach length including the pocket defines a sedimentograph boundary layer, where the effects of sediment feed fluctuation are felt.
KW - advective-diffusive morphodynamics
KW - bedrock-alluvial river
KW - channel evolution
KW - sediment supply
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U2 - 10.1029/2017JF004431
DO - 10.1029/2017JF004431
M3 - Article
AN - SCOPUS:85052393928
VL - 123
SP - 1731
EP - 1755
JO - Journal of Geophysical Research: Earth Surface
JF - Journal of Geophysical Research: Earth Surface
SN - 2169-9003
IS - 8
ER -