Cumulative effect of baroclinic gradient on the residual water level in estuaries and its underlying mechanism

Yang Hao; Ou Suying; Yao Peng; Guo Xiaojuan; Yang Qingshu; Cai Huayang

doi:10.3969/j.issn.0253-4193.2019.01.003

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Yang Hao, Ou Suying, Yao Peng, Guo Xiaojuan, Yang Qingshu, Cai Huayang. Cumulative effect of baroclinic gradient on the residual water level in estuaries and its underlying mechanism[J]. Haiyang Xuebao, 2019, 41(1): 21-31. doi: 10.3969/j.issn.0253-4193.2019.01.003

Citation:

Yang Hao, Ou Suying, Yao Peng, Guo Xiaojuan, Yang Qingshu, Cai Huayang. Cumulative effect of baroclinic gradient on the residual water level in estuaries and its underlying mechanism[J]. Haiyang Xuebao, 2019, 41(1): 21-31. doi: 10.3969/j.issn.0253-4193.2019.01.003

Citation:

Yang Hao, Ou Suying, Yao Peng, Guo Xiaojuan, Yang Qingshu, Cai Huayang. Cumulative effect of baroclinic gradient on the residual water level in estuaries and its underlying mechanism[J]. Haiyang Xuebao, 2019, 41(1): 21-31. doi: 10.3969/j.issn.0253-4193.2019.01.003

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Cumulative effect of baroclinic gradient on the residual water level in estuaries and its underlying mechanism

doi: 10.3969/j.issn.0253-4193.2019.01.003

Institute of Estuarine and Coastal Research, School of Marine Engineering and Technology, Sun Yat-sen University, Guangzhou 510275, China;State and Local Joint Engineering Laboratory of Estuarine Hydraulic Technology, Guangzhou 510275, China

Received Date: 2017-11-25
Rev Recd Date: 2018-07-11

Abstract

Abstract

Residual water level (i.e. the tidally averaged water level) is mainly controlled by the tide-river interaction, and understanding its formation and evolution is important with regard to water resources management in estuaries. In this study, based on the three-dimensional baroclinic hydrodynamic numerical results under different tide-river conditions and the Chebyshev polynomial decomposition approach, the impact of the baroclinic gradient on residual water level variation was explored for given idealized geometry with a convergent width and a linear bed slope. Model results show that the variation of residual water level along the estuary axis is determined by freshwater discharge, tidal amplitude, convergent topography and baroclinic gradient. In particular, the influence of the baroclinic gradient on the residual water level is featured by an accumulative effect over the whole backwater zone, with a significant spring-neap and wet-dry changes. Information of water level and velocity field are provided by numerical model, making use of Chebyshev polynomial decomposition, it is possible to decompose the residual water level into different components, linking to tide, river and tide-river interaction, respectively. When compared with the residual water level induced by baroclinic gradient, it is shown that, the residual water level in backwater zone is primarily controlled by the tide-river interaction. Effect of baroclinic gradient on the residual water level becomes important during the neap tide and may become the dominant factor on the residual water level.
- idealized geometry,
- residual water level,
- baroclinic gradient,
- Chebyshev polynomial decomposition,
- numerical simulation

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