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Physics of estuaries and coastal seas
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Investigation into the spatial and temporal tide-river dynamics and the underlying controlled factors in the Yangtze estuary
P-P1-04-S
Huang Jingzheng* , Institute of Estuarine and Coastal Research, School of Marine Sciences ,Sun Yat-sen University
Cai Huayang, Institute of Estuarine and Coastal Research, School of Marine Sciences ,Sun Yat-sen University
Wu Zheng, College of Water Conservancy and Hydropower Engineering, Hohai University
Presenter Email: 956884377@qq.com |
| Abstract: As tidal waves propagate into the estuary, they are featured by significant longitudinal variation in seasonal scale due to the nonlinear interactions between tide and river discharge. In this study, the variations of tide-river dynamics in terms of tidal damping rate, wave celerity and residual water level slope were explored based on long-term time series of tidal water levels from 2002 to 2014 along the Yangtze estuary (including the Tianshenggang, Jiangyin, Zhenjiang, Nanjing, Maanshan and Wuhu stations) in together with the monthly averaged river discharge observed at Datong hydrological stations. Subsequently, the underlying controlled factors that influence the tidal wave propagation were discussed. It was shown that the seasonal difference in tide-river dynamics was gradually reduced in the seaward direction. We identified a transitional zone located between the Tianshenggang and Jiangyin stations, where the seasonal differences in tidal range are +0.01 m and -0.04 m, respectively. Generally, upstream from Jiangyin station the dynamics character was river-dominated, while in the lower reaches it was mainly controlled by the tidal forcing. In addition, we show that there exists a threshold in river discharge in the upper reaches of the Yangtze estuary due to the increase of residual water level and hence water depth caused by the residual water level slope. This phenomenon was particularly true in the upstream reach between Maanshan to Wuhu, where the threshold of river discharge was approximately 33000 m3s-1. The results obtained from this study can enhance our understanding of tide-river interaction, and will, hopefully, provide guidelines for water resources management in the Yangtze estuary.
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