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Origin of a preferential avulsion node on lowland river deltas

Chadwick, A. J. and Lamb, M. P. and Moodie, A. J. and Parker, G. and Nittrouer, J. A. (2019) Origin of a preferential avulsion node on lowland river deltas. Geophysical Research Letters, 46 (8). pp. 4267-4277. ISSN 0094-8276. doi:10.1029/2019gl082491.

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River deltas are built by cycles of lobe growth and abrupt channel shifts, or avulsions, that occur within the backwater zone of coastal rivers. Previous numerical models differ on the origin of backwater‐scaled avulsion nodes and their consistency with experimental data. To unify previous work, we developed a numerical model of delta growth that includes backwater hydrodynamics, river mouth progradation, relative sea level rise, variable flow regimes, and cycles of lobe growth, abandonment, and reoccupation. For parameter space applicable to lowland deltas, we found that flow variability is the primary mechanism to cause persistent avulsion nodes by focusing aggradation within the backwater zone. Backwater‐scaled avulsion nodes also occur under less likely scenarios of initially uniform bed slopes or during rapid relative sea level rise and marine transgression. Our findings suggest that flow variability is a fundamental control on long‐term delta morphodynamics.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemData ItemCode
Chadwick, A. J.0000-0002-2552-0083
Lamb, M. P.0000-0002-5701-0504
Moodie, A. J.0000-0002-6745-036X
Parker, G.0000-0001-5973-5296
Nittrouer, J. A.0000-0002-4762-0157
Additional Information:© 2019 American Geophysical Union. Received 17 FEB 2019; Accepted 31 MAR 2019; Accepted article online 4 APR 2019; Published online 25 APR 2019. We acknowledge National Science Foundation grant EAR 1427262 and the Resnick Sustainability Institute at Caltech for support. We thank Vamsi Ganti, Gail Kineke, Ben Hobbs, Hongbo Ma, Brandee Carlson, Kensuke Naito, and Lisa Kumpf for insightful discussions, and Elizabeth Hajek and Wonsuck Kim for constructive reviews. Data are available at: Code is available at:
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Resnick Sustainability InstituteUNSPECIFIED
Subject Keywords:river avulsion; avulsion node; delta apex; lowland deltas; flood variability; backwater
Issue or Number:8
Record Number:CaltechAUTHORS:20190409-112905807
Persistent URL:
Official Citation:Chadwick, A. J., Lamb, M. P., Moodie, A. J., Parker, G., & Nittrouer, J. A. (2019). Origin of a preferential avulsion node on lowland river deltas. Geophysical Research Letters, 46, 4267–4277.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94588
Deposited By: Tony Diaz
Deposited On:09 Apr 2019 19:27
Last Modified:16 Nov 2021 17:06

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