System-Wide Effects of Local Bed Disturbance on the Morphological Evolution of a Bifurcating Channel Network

Journal Article (2024)
Author(s)

Weilun Gao (Guangdong University of Technology)

Dongdong Shao (Beijing Normal University)

Zheng Bing Bing Wang (TU Delft - Coastal Engineering, Deltares)

Zhenchang Zhu (Southern Marine Science and Engineering Guangdong Laboratory, Guangdong University of Technology)

Zhifeng Yang (Southern Marine Science and Engineering Guangdong Laboratory, Guangdong University of Technology)

Research Group
Coastal Engineering
Copyright
© 2024 Weilun Gao, Dongdong Shao, Zhengbing Wang, Zhenchang Zhu, Zhifeng Yang
DOI related publication
https://doi.org/10.1029/2023JF007514
More Info
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Publication Year
2024
Language
English
Copyright
© 2024 Weilun Gao, Dongdong Shao, Zhengbing Wang, Zhenchang Zhu, Zhifeng Yang
Research Group
Coastal Engineering
Issue number
3
Volume number
129
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Abstract

Deltaic channel networks are important conduits for water and material supplies to the fluvial and coastal communities. However, increasing human interventions in river deltas have altered the topology and geometry of channel networks as well as their long-term evolution. While the morphological evolution of a single channel has received extensive studies, the system-wide morphological responses of channel networks to local disturbances remain largely unclear. Here we investigate the morphological responses of a bifurcating channel network subject to local disturbance of channel deepening due to dredging and sand mining through idealized simulations, and further compare the results with the reference scenarios of a single channel and theoretical analysis of the phase plane. The results show that the infilling of the local deepening is associated with the erosion of the entire branch, which also causes system-wide effects on the siltation of the other branch. The morphological responses of the bifurcating channel network consist of a relatively short stage for the infilling of the local deepening followed by a relatively long stage for recovering the equilibrium configuration of the river bifurcation. The system-wide effects of the local disturbance arise from the altered water surface slope and water partitioning downstream of the bifurcation due to the local deepening. Also, the prolonged recovery of the equilibrium configuration is consistent with theoretical analysis, which reveals a slow evolution of the bifurcation when approaching the equilibrium. Our results can help understand the long-term morphological responses of large-scale complex channel networks and inform water managements under increasing human interventions.

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