Hydrodynamic Modelling Techniques for Bays and Estuaries: Simulation Methodology and Practical Application

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a novel simulation methodology for hydrodynamic modeling in bays and estuaries, addressing the critical issue of data scarcity. By simplifying calibration to a single parameter—bed friction—it offers a practical and innovative approach for regions with limited field data. The methodology is rigorously developed, grounded in mass and momentum conservation equations, and validated through comprehensive comparisons with analytical solutions.

Minor grammatical corrections are suggested for clarity:

"shoes" should be corrected to "shows" (Line 344),

"towerds" to "towards" (Line 338),

and "designeers" to "designers" (Line 332).

The study's relevance lies in its potential application for pre-feasibility studies, optimizing water resource management. I recommend the manuscript for publication with these minor revisions.

Author Response

Dear Reviewer:

Please take a look at the file I've attached.

Kind regards,

The authors

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

please find attached.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer:

Please take a look at the file I've attached.

Kind regards,

The authors

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript addresses the topic in hydrodynamic modeling by proposing a simplified simulation methodology tailored to bays and estuarine systems with data-scarce conditions. The research provides a novel approach using a single calibration parameter (bed friction) and applies it to a one-dimensional linear open channel for validation. However, some aspects require clarification, refinement, and additional analysis for better comprehension and broader impact. The following points outline specific feedback and recommendations for improvement.

1. The overall writing lacks the rigor expected of a journal article. The manuscript should be rewritten to meet the quality standards of the journal.

2. Please address consistency issues in the governing equations by clearly explaining the inclusion or exclusion of terms such as viscosity, Coriolis force, and density variations. Issues with equations include:

   a. The Coriolis force in Equation (9b) is not accurately represented.

   b. The source of the bottom friction term in Equations (9) should be clarified, and the meaning of the coefficient C should be explicitly defined.

   c. The term F(x) in Equation (9a) changes to F_x in Equation (10). This transformation is not explained and needs clarification.

   d. The hydraulic radius R in Equation (11) becomes R_x in Equation (12). The difference and the rationale for this transformation should be clarified to ensure it is reasonable.

   e. The description of the discretization process for the equations is imprecise and requires more detailed explanation.

3. The study redefines the hydraulic radius in the discretized grid (Table 1) to calculate frictional forces rather than using the traditional definition for channels. However, the manuscript does not cite precedents for this approach or provide a theoretical justification for its validity. Additionally, the potential limitations or inaccuracies of this redefinition should be discussed, particularly regarding its applicability to real-world scenarios and its consistency with physical principles.

4. The friction factor f mentioned in Section 3.2 is not included in the fundamental equations, making its role and significance unclear. This should be addressed to improve the reader's understanding.

5. Figures 1 and 2 are overly similar and do not provide enough distinct information. Consider consolidating or differentiating them.

6. For Figures 7 to 9, if they represent comparisons between numerical and analytical solutions, the numerical and analytical solutions should be explicitly labeled.

7. Figure 10 requires a legend to indicate the f values represented by each line. Additionally, the unit of the horizontal axis (Position) should be specified.

8. The comparison presented in Figures 12 to 14 does not effectively demonstrate the variation of velocity (and water level) over time and space. Given that this is a simple case with an analytical solution, it should be feasible to compare the temporal and spatial distributions of water level and velocity directly. This would provide a clearer and more comprehensive validation of the model.

Author Response

Dear Reviewer:

Please take a look at the file I've attached.

Kind regards,

The authors

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The revised manuscript has addressed most of the previous review comments; however, several critical issues remain unresolved. The following revisions are recommended to enhance the quality of the manuscript to meet the standard for publication:

1. In Eq. (8b), the Coriolis force term should be -f_c U instead of -f_c V. The current form appears to be incorrect.
2. The original momentum conservation equation (Eq. (6)) is formulated as the inviscid Euler equations. However, in Eq. (8), frictional force terms at the solid boundary are introduced. This creates an inconsistency in the derivation of the governing equations, which undermines the rigor of the manuscript. Since the final depth-averaged shallow water equations include bed friction terms, the initial governing equations should also account for viscosity.
3. On Page 21, Line 550, the definition of A (used for computing s as s = AT) is not provided. Please clarify this in the manuscript.
4. The manuscript presents only a one-dimensional straight channel problem, which is insufficient to demonstrate the capabilities of the proposed model. It is strongly recommended to include a two-dimensional meandering channel simulation to better illustrate the model’s effectiveness. Furthermore, in the one-dimensional test cases presented in the paper, each channel cross-section consists of only one computational grid, meaning that only a single hydraulic radius is used per section. As a result, the validity of the hydraulic radius calculation methods proposed in Table 1 cannot be properly assessed. The authors should select a simple two-dimensional meandering case to better evaluate the model’s performance.
5. In Appendix A, using a linear-wave solution to validate the ratio of local acceleration term to convective acceleration term appears to be a misplaced approach. Since the analytical solution is linear, it inherently implies that the convective acceleration terms are relatively small. Instead of using a linear-wave solution to justify the ratio, the authors should refer to the conventional treatment in shallow water models when discussing this issue.

By addressing these points, the manuscript can be significantly improved and made suitable for publication.

Author Response

Dear Reviewer 3: 

Please see the enclosed file.

Kind regards, 

The authors

Author Response File: Author Response.pdf