Preprints
https://doi.org/10.5194/hess-2021-75
https://doi.org/10.5194/hess-2021-75

  26 Feb 2021

26 Feb 2021

Review status: this preprint was under review for the journal HESS but the revision was not accepted.

River-enhanced non-linear overtide variations in river estuaries

Leicheng Guo1, Chunyan Zhu1,2, Huayang Cai3, Zheng Bing Wang1,2,4, Ian Townend5, and Qing He1 Leicheng Guo et al.
  • 1State Key Lab of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
  • 2Department of Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft 2600GA, the Netherlands
  • 3School of Marine Engineering and Technology, Sun Yat-Sen University, Guangzhou, China
  • 4Marine and Coastal Systems Department, Deltares, Delft 2629 HV, the Netherlands
  • 5School of Ocean and Earth Sciences, University of Southampton, Southampton, UK

Abstract. Tidal waves traveling into estuaries are modulated in amplitude and shape due to bottom friction, funneling planform and river discharge. The role of river discharge on damping incident tides has been well-documented, whereas our understanding of the impact on overtide is incomplete. Inspired by findings from tidal data analysis, in this study we use a schematized estuary model to explore the variability of overtide under varying river discharge. Model results reveal significant M4 overtide generated inside the estuary. Its absolute amplitude decreases and increases in the upper and lower parts of the estuary, respectively, with increasing river discharge. The total energy of the M4 tide integrated throughout the estuary reaches a transitional maximum when the river discharge to tidal mean discharge (R2T) ratio is close to unity. We further identify that the quadratic bottom stress plays a dominant role in governing the M4 variations through strong river-tide interaction. River flow enhances the effective bottom stress and dissipation of the principal tides, and reinforces energy transfer from principal tide to overtide. The two-fold effects explain the nonlinear M4 variations and the intermediate maximum threshold. The model results are consistent with data analysis in the Changjiang and Amazon River estuaries and highlight distinctive tidal behaviors between upstream tidal rivers and downstream tidal estuaries. The new findings inform study of compound flooding risk, tidal asymmetry, and sediment transport in river estuaries.

Leicheng Guo et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-75', Xiao Hua Wang, 08 Apr 2021
    • AC1: 'Reply on RC1', Leicheng Guo, 16 Apr 2021
      • RC2: 'Reply on AC1', Xiao Hua Wang, 17 Apr 2021
        • AC2: 'Reply on RC2', Leicheng Guo, 28 May 2021
  • RC3: 'Comment on hess-2021-75', Anonymous Referee #2, 27 Apr 2021
    • AC3: 'Reply on RC3', Leicheng Guo, 28 May 2021
  • RC4: 'Comment on hess-2021-75', Anonymous Referee #3, 29 Apr 2021
    • AC4: 'Reply on RC4', Leicheng Guo, 28 May 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-75', Xiao Hua Wang, 08 Apr 2021
    • AC1: 'Reply on RC1', Leicheng Guo, 16 Apr 2021
      • RC2: 'Reply on AC1', Xiao Hua Wang, 17 Apr 2021
        • AC2: 'Reply on RC2', Leicheng Guo, 28 May 2021
  • RC3: 'Comment on hess-2021-75', Anonymous Referee #2, 27 Apr 2021
    • AC3: 'Reply on RC3', Leicheng Guo, 28 May 2021
  • RC4: 'Comment on hess-2021-75', Anonymous Referee #3, 29 Apr 2021
    • AC4: 'Reply on RC4', Leicheng Guo, 28 May 2021

Leicheng Guo et al.

Leicheng Guo et al.

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Short summary
Overtide is a shallow water tidal component and its interaction with astronomical tides induces tidal wave deformation, which is an important process that controls sediment transport. We use a numerical tidal model to examine overtide changes in estuaries under varying river discharges and find spatially nonlinear changes and the threshold of an intermediate river that benefits maximal overtide generation. The findings inform management of sediment transport and flooding risk in estuaries.