Preprints
https://doi.org/10.5194/egusphere-2022-175
https://doi.org/10.5194/egusphere-2022-175
 
22 Apr 2022
22 Apr 2022

Quantifying the impacts of the Three Gorges Dam on the spatial-temporal water level dynamics in the Yangtze River estuary

Huayang Cai1,2, Hao Yang1,2, Pascal Matte3, Haidong Pan4, Zhan Hu5, Tongtiegang Zhao6, and Guangliang Liu7 Huayang Cai et al.
  • 1Institute of Estuarine and Coastal Research/State and Local Joint Engineering Laboratory of Estuarine Hydraulic Technology, School of Ocean Engineering and Technology, Sun Yat-sen University, Guangzhou, 510275, China
  • 2Guangdong Provincial Engineering Research Center of Coasts, Islands and Reefs/Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China
  • 3Meteorological Research Division, Environment and Climate Change Canada, Quebec, QC G1J 0C3, Canada
  • 4First Institute of Oceanography, and Key Laboratory of Marine Science and Numerical Modeling, Ministry of Natural Resources, Qingdao, 266061, China
  • 5School of Marine Sciences, Sun Yat-sen University, Zhuhai, 519082, China
  • 6School of Civil Engineering, Sun Yat-sen University, Zhuhai, 519082, China
  • 7Shandong Provincial Key Laboratory of Computer Networks, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China

Abstract. Understanding the alterations in spatial-temporal water level dynamics caused by natural and anthropogenic changes is essential for water resources management in estuaries, as this can directly impact the estuarine morphology, sediment transport, salinity intrusion, navigation conditions, and other factors. Here, we propose a simple triple linear regression model linking the water level variation on a daily timescale to the hydrodynamics at both ends of an estuary. The model was applied to the Yangtze River estuary (YRE) for examining the influence of the world’s largest dam, the Three Gorges Dam (TGD), on the spatial-temporal water level dynamics within the estuary. It is shown that the regression model can accurately reproduce the water level dynamics in the YRE, with a root mean squared error (RMSE) of 0.063–0.151 m seen at five gauging stations for both the pre- and post-TGD periods. This confirms the hypothesis that the response of water level dynamics to hydrodynamics at both ends is mostly linear in the YRE. The regression model calibrated during the pre-TGD period was used to reconstruct the water level dynamics that would have occurred in absence of the TGD's freshwater regulation. Results show that the spatial-temporal alterations in water levels during the post-TGD period are mainly driven by the variation in freshwater discharge due to the regulation of the TGD, which results in increased discharge during the dry season (from December to March) and a dramatic reduction in discharge during the wet-to-dry transitional period. The presented method to quantify the separate contributions made by changes in boundary conditions and geometry on spatial-temporal water level dynamics is particularly useful for determining scientific strategies for sustainable water resources management in dam-controlled estuaries worldwide.

Huayang Cai et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-175', Anonymous Referee #1, 31 May 2022
    • AC1: 'Reply on RC1', Guangliang Liu, 11 Jun 2022
  • RC2: 'Comment on egusphere-2022-175', XI FENG, 16 Aug 2022
    • AC2: 'Reply on RC2', Guangliang Liu, 29 Aug 2022

Huayang Cai et al.

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Short summary
Quantifying the spatial-temporal water level dynamics is essential for water resources management in estuaries. In this study, we propose a simple yet powerful regression model to examine the influence of the world’s largest dam, the Three Gorges Dam (TGD), on the spatial-temporal water level dynamics within the Yangtze River estuary. The presented method is particularly useful for determining scientific strategies for sustainable water resources management in dam-controlled estuaries worldwide.