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Modeling deltaic lobe‐building cycles and channel avulsions for the Yellow River delta, China

Moodie, Andrew J. and Nittrouer, Jeffrey A. and Ma, Hongbo and Carlson, Brandee N. and Chadwick, Austin J. and Lamb, Michael P. and Parker, Gary (2019) Modeling deltaic lobe‐building cycles and channel avulsions for the Yellow River delta, China. Journal of Geophysical Research. Earth Surface, 124 (11). pp. 2438-2462. ISSN 2169-9003. https://resolver.caltech.edu/CaltechAUTHORS:20191014-133706256

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Abstract

River deltas grow by repeating cycles of lobe development punctuated by channel avulsions, so that over time, lobes amalgamate to produce a composite landform. Existing models have shown that backwater hydrodynamics are important in avulsion dynamics, but the effect of lobe progradation on avulsion frequency and location has yet to be explored. Herein, a quasi‐2‐D numerical model incorporating channel avulsion and lobe development cycles is developed. The model is validated by the well‐constrained case of a prograding lobe on the Yellow River delta, China. It is determined that with lobe progradation, avulsion frequency decreases, and avulsion length increases, relative to conditions where a delta lobe does not prograde. Lobe progradation lowers the channel bed gradient, which results in channel aggradation over the delta topset that is focused farther upstream, shifting the avulsion location upstream. Furthermore, the frequency and location of channel avulsions are sensitive to the threshold in channel bed superelevation that triggers an avulsion. For example, avulsions occur less frequently with a larger superelevation threshold, resulting in greater lobe progradation and avulsions that occur farther upstream. When the delta lobe length prior to avulsion is a moderate fraction of the backwater length (0.3–0.5L_b), the interplay between variable water discharge and lobe progradation together set the avulsion location, and a model capturing both processes is necessary to predict avulsion timing and location. While this study is validated by data from the Yellow River delta, the numerical framework is rooted in physical relationships and can therefore be extended to other deltaic systems.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019jf005220DOIArticle
ORCID:
AuthorORCID
Moodie, Andrew J.0000-0002-6745-036X
Nittrouer, Jeffrey A.0000-0002-4762-0157
Ma, Hongbo0000-0002-6017-8113
Carlson, Brandee N.0000-0002-5369-9746
Chadwick, Austin J.0000-0002-2552-0083
Lamb, Michael P.0000-0002-5701-0504
Parker, Gary0000-0001-5973-5296
Additional Information:© 2019 American Geophysical Union. Received 21 JUN 2019; Accepted 20 SEP 2019; Accepted article online 15 OCT 2019. A. J. M., J. A. N., H. M., B. N. C., A. J. C., M. P. L., and G. P. acknowledge support from the National Science Foundation (NSF) EAR‐1427262 Coastal SEES grant. A. J. M. was supported by a NSF Graduate Research Fellowship under Grant 1842494. A. J. C. was supported by the Resnick Sustainability Institute at Caltech. G. P. was supported by the NSF Grant EAR‐1209402. The authors sincerely thank Vamsi Ganti and two anonymous reviewers for their thoughtful critique of this manuscript. The model code and supporting data can be obtained online (https://github.com/amoodie/paper_resources/Moodie_deltaiclobebuilding).
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NSFEAR-1427262
NSF Graduate Research FellowshipDGE-1842494
Resnick Sustainability InstituteUNSPECIFIED
NSFEAR-1209402
Subject Keywords:river avulsion; lowland deltas; backwater; deltaic lobe
Issue or Number:11
Record Number:CaltechAUTHORS:20191014-133706256
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191014-133706256
Official Citation:Moodie, A. J., Nittrouer, J. A., Ma, H., Carlson, B. N., Chadwick, A. J., Lamb, M. P., & Parker, G. (2019). Modeling deltaic lobe‐building cycles and channel avulsions for the Yellow River delta, China. Journal of Geophysical Research: Earth Surface, 124, 2438–2462. https://doi.org/10.1029/2019JF005220
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99254
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Oct 2019 21:15
Last Modified:04 May 2020 17:39

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