Abstract
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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1731-1755 |
| Number of pages | 25 |
| Journal | Journal of Geophysical Research: Earth Surface |
| Volume | 123 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 2018 |
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Keywords
- advective-diffusive morphodynamics
- bedrock-alluvial river
- channel evolution
- sediment supply
ASJC Scopus subject areas
- Geophysics
- Forestry
- Oceanography
- Aquatic Science
- Ecology
- Water Science and Technology
- Soil Science
- Geochemistry and Petrology
- Earth-Surface Processes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
- Palaeontology
Cite this
The Advective-Diffusive Morphodynamics of Mixed Bedrock-Alluvial Rivers Subjected to Spatiotemporally Varying Sediment Supply. / Zhang, Li; Stark, Colin; Schumer, Rina; Kwang, Jeffrey; Li, Tiejian; Fu, Xudong; Wang, Guangqian; Parker, Gary.
In: Journal of Geophysical Research: Earth Surface, Vol. 123, No. 8, 08.2018, p. 1731-1755.Research output: Contribution to journal › Article
}
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
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
UR - http://www.scopus.com/inward/record.url?scp=85052393928&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85052393928&partnerID=8YFLogxK
U2 - 10.1029/2017JF004431
DO - 10.1029/2017JF004431
M3 - Article
AN - SCOPUS:85052393928
VL - 123
SP - 1731
EP - 1755
JO - Journal of Geophysical Research D: Atmospheres
JF - Journal of Geophysical Research D: Atmospheres
SN - 0148-0227
IS - 8
ER -