Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

Xie, Dongfeng; Pan, Cunhong; Gao, Shu; Wang, Zhengbing

doi:10.1016/j.margeo.2018.09.003

Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

Title

Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

Author

Xie, Dongfeng (Zhejiang Institute of Hydraulics and Estuary; Zhejiang Provincial Key Laboratory for Estuarine and Coastal Research)
Pan, Cunhong (Zhejiang Institute of Hydraulics and Estuary; Zhejiang Provincial Key Laboratory for Estuarine and Coastal Research)
Gao, Shu (East China Normal University)
Wang, Zhengbing (TU Delft Coastal Engineering; Deltares)

Date

2018

Abstract

The importance of seasonal variations in river discharge on the morphological development of estuaries has been recognized in recent years, yet in situ observations about such variations are rare. Here we report a long-term dataset of bathymetry in the middle reach of the Qiantang Estuary, China, characterized by the presence of a large inner bar. Moreover, a hydrographic survey was carried out in the Yanguan reach where one of the largest tidal bores in the world occurs, covering a spring-neap tidal cycle in 2015. Meanwhile, detailed seasonal bathymetric data together with daily river discharges of 2015 were collected. The bed morphology shows strong seasonal and inter-annual variations. During the high flow season, the river flow erodes the bed and transports a large amount of sediments seaward. A good power-law relationship exists between the high river discharge and the channel volume at the upper estuary. Flood tides dominate under usual river flow condition. In particular, the tidal bore during spring and intermediate tides is characterized by large current velocity and high suspended sediment concentration, and transports a large amount of sediment landward. Over a year, a dynamic morphological equilibrium can be maintained. Moreover, the estuary has also been significantly influenced by the large-scale embankment in recent decades, constraining the lateral thalweg migration, bank erosion and point bar deposition, which usually occur in natural sinuous estuaries.

Subject

Morphodynamic equilibrium
Sediment transport
River discharge
Tidal bore
Qiantang Estuary
Hangzhou Bay

To reference this document use:

http://resolver.tudelft.nl/uuid:5609ed78-47f5-468a-97c0-65814153746a

DOI

https://doi.org/10.1016/j.margeo.2018.09.003

Embargo date

2020-09-11

ISSN

0025-3227

Source

Marine Geology, 406, 27-33