Title
A historical review of sediment export–import shift in the North Branch of Changjiang Estuary
Author
Guo, Leicheng (East China Normal University)
Xie, Weiming (East China Normal University)
Xu, Fan (East China Normal University)
Wang, Xianye (East China Normal University)
Zhu, C. (TU Delft Coastal Engineering; East China Normal University)
Meng, Yi (East China Normal University)
Zhang, Weiguo (East China Normal University)
He, Qing (East China Normal University)
Date
2021
Abstract
Net sediment transport is predominantly seaward in fluvial-dominated estuaries worldwide. However, a distributary branch in the Changjiang Estuary, the North Branch, undergoes net landward sediment transport, which leads to severe channel aggradation. Its controlling mechanism and the role of human activities remain insufficiently understood, although such knowledge is necessary for better management and restoration opportunities. In this study we revisit the centennial hydro-morphodynamic evolution of the North Branch based on historical maps, field data, and satellite images and provide a synthesis of the regime change from ebb to flood dominance. The North Branch was once a major river and ebb-dominant distributary channel. Within which alternative meandering channels and sand bars developed. Deposition of river-borne sediment leads to infilling of the branch, while tidal flat embankment reduces the bankfull width and modifies the channel configuration, resulting in a profound decline in the sub-tidal flow partition rate. The North Branch then becomes tide-dominant with an occurrence of tidal bores and elongated sand ridges. Once tidal dominance is established, extensive tidal flat reclamation enhances the funnel-shaped planform, amplifying the incoming tides and initiating a positive feedback process that links tidal flat loss, sediment import, and channel aggradation. Overall, the shift in branch dominance is a combined result of a natural southeastward realignment of the deltaic distributary channels and extensive reclamation. One management option to mitigate channel aggradation is to stop the aggressive reclamation and allow tidal flats to build up, which might reduce the sediment import and eventually lead to a morphodynamic equilibrium in the longer term. Understanding the impact of tidal flat reclamation is informative for the management of similar tidal systems under strong human interference.
Subject
Changjiang
flood dominance
morphodynamics
reclamation
regime shift
To reference this document use:
http://resolver.tudelft.nl/uuid:ab6bccc6-d8ba-4a3c-99d0-fe7a156c53da
DOI
https://doi.org/10.1002/esp.5084
Embargo date
2021-07-29
ISSN
0197-9337
Source
Earth Surface Processes and Landforms, 47 (1), 5-16
Bibliographical note
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
Part of collection
Institutional Repository
Document type
review
Rights
© 2021 Leicheng Guo, Weiming Xie, Fan Xu, Xianye Wang, C. Zhu, Yi Meng, Weiguo Zhang, Qing He