Impacts of Riverine Floods on Morphodynamics in the Yellow River Delta

Round 1

Reviewer 1 Report

Impacts of riverine floods on morphodynamics in the Yellow River Delta:

·        Discuss the most important reasons for the Bathymetric changes induced by high riverine flows in the flood seasons.

·        “The superposition of low sediment loads and extreme riverine floods can cause significant variations in erosion/deposition patterns of deltas”. Explain.

·        “Most mega-deltas are currently undergoing irreversible changes triggered by diminishing sediment supply, rising sea level, intensive human interferences, and frequent catastrophic events”. Explain.

·        In the Tables, highlight values that are more important and discuss them for better understanding readers.

·        Focus on the advantages/disadvantages of the proposed method concerning the obtained results.

·        How can expand the results to other regions with similar/different climates?

·        At the end of the manuscript, explain the implications and future works considering the outputs of the current study.

 

·        The quality of the language needs to be improved for grammatical style and word use.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript describes a study that uses a three-dimensional hydrodynamic model to investigate hydrodynamic changes in the Bohai Sea. The authors set up the model using the Delft3D model and validated the model by comparing the modelled and observed data for water levels and flow velocities. The authors considered six different runoff scenarios to simulate low, moderate, and high runoff during the flood season. The hydrodynamic parameters, including water level, flow velocity, and bed shear stress, were obtained through post-processing with Delft3D-QUICKPLOT. The authors examined the hydrodynamic effects of high-energy riverine floods by contrasting high and low runoffs during the flood seasons.

The authors suggest that high runoff during the flood season can cause significant changes in fluvial-tidal hydrodynamics, particularly in the abandoned delta lobe. This can lead to high flow velocities and bed shear stresses near the abandoned river mouth, resulting in changes in the erosion-accretion patterns of the submerged delta. Furthermore, the authors discuss the impact of high riverine floods on sediment transport and resuspension processes, leading to the formation of high-turbidity zones. The authors also discuss the role of sufficient sediment supply in the geomorphic evolution of the river-dominated delta.

The manuscript suggest that the superposition of low sediment loads and extreme riverine floods can cause significant variations in erosion/deposition patterns of deltas.  and explained the detailed and informative, covering various aspects related to the effects of river discharge on deltaic hydrodynamics and sediment transport processes.

Although, the study has some limitations. Firstly, the authors did not consider water temperature, sediment, salinity, and wind waves, which can affect hydrodynamics in the Bohai Sea. Secondly, the study only considered a 45-day period (from 17 July 2018 to 31 August 2018), and the model results for the latter 30 days were used for subsequent analysis to remove the initial influence in the former 15 days lead-in phase. Therefore, the findings may not be representative of the long-term hydrodynamic changes in the Bohai Sea. Thirdly, the Manning coefficient was calculated using bathymetric data, which may have introduced errors in the model. The study did not discuss the limitations of the Delft3D model, which has some limitations, such as the assumption of hydrostatic pressure and the lack of consideration of sub-grid turbulence. Finally, the discussion could benefit from a more detailed explanation of the methodology used to obtain the results presented. Additionally, the authors could discuss the implications of their findings for future research in the field of deltaic hydrodynamics and sediment transport processes. Bathymetric variations can present hydrodynamics changes and sediment delivery.

 

The study provides valuable insights into the hydrodynamic changes in the Bohai Sea. However, the findings should be interpreted with caution due to the limitations of the study. Future studies could consider the factors that were not included in this study and use more sophisticated models to investigate hydrodynamic changes in the Bohai Sea.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I appreciate the authors addressing the comments. The manuscript can be accepted in its current form. Congrats!

Reviewer 2 Report

the authors addressed the reviewer's comments and greatly improved the manuscript text. 

the manuscript may be accepted for the publication