Investigation of Morphological Changes in the Tamsui River Estuary Using an Integrated Coastal and Estuarine Processes Model

Round 1

Reviewer 1 Report

Re-review of “Investigation of Morphological Changes in Tamsui River Estuary Using Integrated Coastal and Estuarine Process Model” by Hsieh et al.

I re-reviewed this article. The authors have carefully revised the original manuscript based on the editor’s and reviewer’s comments, but it’s insufficient to publish this research as a paper of “Water”. My comments are as follows. You should revise the manuscript again, and then resubmit it.

• Basically, the citation should be shown using the only reference number in an article of “Water”. But you showed the author name and year with the reference number, such as Lines 76-85, Lines 132-136. Please carefully read “Instructions for Authors”. https://www.mdpi.com/journal/water/instructions
• Figures: Please show the meaning of the symbols/lines/colors in the caption or panel. In particular, it is very difficult to see the characters in Figure 3. The area of Figure 3 should be shown in Figure 1. The broken line area differs from the area of Figure 3. By the way, isn’t it necessary to show the copyright of the satellite image of Figure 3? As mentioned by the previous review, Water will publish an article under a CC By open access license. You should carefully use the satellite images.
• Lines 317-330: I doubt how to evaluate the difference between the calculated results and observed values. You defined E_i as the error between the simulated and observed values (i.e., m_i-O_i). Considering RMSE based on this definition, RMSE is as follows.

Is this correct? I think that E_i should be the simulated values. Please check other equations (eqs. (3)-(6)). And you should clarify why you need four parameters for evaluating the difference between simulation and observation. In particular, you shouldn’t use R² because R² is the proportion of the variance in the dependent variable that is predictable from independent variables. Thus, R² is usually shown when demonstrating the validity of modeling, such as a regression analysis. If necessary, this should be the Pearson correlation coefficient.

• Lines 371-387: This validation is very important for your research. But I don’t understand the validity of your simulation. Can you justify the simulation of morphological changes more clearly? You should demonstrate that the accuracy of your simulation is enough to discuss the bed changes by the construction of the Amuping desilting tunnel.
• Lines 398-401: I don’t understand the sediment delivery ratio in the base scenario. Why do you select 36.2%?
• Lines 432-433: Figure 16(b)?
• Line 435: I don’t understand how to calculate the sediment flux. What values are 0.0021 and 2640?
• Figure 13: Is the difference between the simulation results with and without the Amuping desilting tunnel statistically significant?
• Line 479: What are Q₅₀ and Q₁₀₀?
• Lines 474-478: I don’t understand why you select the monsoon event in 2010 and the typhoon event in 2004 for comparison of the morphological changes during the typhoon and monsoon periods.
• I don’t understand the necessary of the section 4. In the section 4, you validated the simulation results in three Typhoon events in 2008. On the other hand, you simulated the morphological changes by the monsoon in 2010, Typhoon Aere in 2004 and Typhoon Soulik in 2013. Why did you validate your numerical model in these events in the section 4? I understand that the section 5 is the most important argument in your research. If so, you should validate the relevant model parameters in these events.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Reviewer report

 

Journal: Water

 

Title: Investigation of Morphological Changes in Tamsui River Estuary Using Integrated Coastal and Estuarine Processes Model

 

Authors: Tung-Chou Hsieh, Yan Ding , Keh-Chia Yeh , Ren-Kai Jhong

 

 

General comment

The paper deals with a case study and discusses the morphological changes of the Tamsui River estuary subject to typhoon and monsoon forcing; the CCHE2D-Coast model was adopted to reproduce the flow field, the sediment transport, the erosion and aggradation along the coast, along with scouring of the estuarine sandbar at the river estuary.

The model was then used to explore the desilting effects on the downstream river channel, and to compare the sediment transport characteristics during a period with monsoon and typhoon-induced flood.

The results  showed that during the typhoon-induced flood period the upstream flood transported a large amount of sediment to be deposited in the estuary, and parts of sediment are transported by currents to reach the sand spit where they are deposited.

The paper is a resubmission of a previous version and appears to be improved with respect to the former manuscript. Some minor revisions –typos are reported below for correction.

 

Minor points

Line 78 : typo Fredsue

Line 100: reference in incorrect, should be Faraci et al (2012)

Line 280: could the authors specify how the numerical grid was made? Where and how does it become thicker?

Figure 8: close to Shalun area in the north direction, the simulated bed changes predict a significant erosion which is not visible in the observed topography. Can the authors comment on this occurrence?

Line 479: what are Q50 and Q100? Have they been defined elsewhere?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have improved the manuscript according to my comments. At present, I agree to publish this article as a paper of “Water”. The authors, however, don’t satisfy my comment of the coefficient of determination. Thus, they should revise the manuscript again according to the following point.

The coefficient of determination differs from the correlation coefficient. When comparing between simulation and observation, you should use the correlation coefficient, but not the coefficient of determination. As commented before, R² is the proportion of the variance in the dependent variable that is predictable from independent variables. Thus, R²is usually shown when demonstrating the validity of modeling, such as a regression analysis.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

please see the attached report

Comments for author File: Comments.pdf

Reviewer 2 Report

Review of “Investigation of Morphological Changes in Tamsui River Estuary Using Integrated Coastal and Estuarine Process Model” by Hsieh et al.

 

In order to assess the impact of a reservoir sediment flush scenario from the upstream on the river morphology downstream, the authors investigated the morphological changes in the Tamsui River Estuary in Taiwan by multiple physical processes using an integrated coastal and estuarine process model (CCHE2D-Coast). They demonstrated that the morphological changes significant differed between during the monsoon and typhoon periods.

The authors eagerly performed several simulations using the coupled models to investigate the morphological changes in the estuary. I positively evaluated the plans and efforts of their research. The authors, however, need many works. Their major weaknesses are a lengthy text and many insufficient and inadequate descriptions. Therefore, at present, the authors don’t prepare to consider this article as a publishing paper of Water. I encourage the authors to resubmit their work after carefully concisely rewriting the paper according to the following comments.

Firstly, the article is too lengthy because of the unnecessary description about the model validation (i.e., Section 4). This description isn’t contributed to your conclusion. You should remove this description from main text for readability, and then move this description to Supplementary materials.

Next, the quality of all figures and the explanations of all symbols/colors in the figure caption are insufficient, and also the order of the figures are inadequate. You should improve the all figures according to the following comments.

Figure 1: Is Figure 1 necessary? I think that the contents are included into Figure 2. Figure 2: Where has the drawing/photograph in Figure 2 been obtain from? Do you or your co-author create/take them? Water will publish an article under a CC BY open access license. If you don’t create/take them, please ensure that they are acknowledged in your figure legend. Figure 3: Figure 3 should be shown in the Introduction. You explain the background of your study, but it would be difficult to understand your explanation because many readers are unfamiliar with your study field. Figure 4: The area of Figure 4 is shown in Figure 3. Figure 5 is better to combine into Figure 4 because the readers are easy to understand your simulation domain. Figure 5: There are no unit of scalebar and axes in Figure 5. And when is the data of initial bed condition in Figure 5? Figure 6: Figure 6 is unnecessary because it’s not very important. Figure 7: Figure 7 is low quality. How time interval of discharge and sediment concentration are? And also, the label of the second vertical axis is inadequate. Probably, the label should be “sediment flux (kg/s)”. And you should clarify the sediment vertical or horizontal fluxes throughout this article. Figure 8: I doubt the accuracy of the tidal simulation. Why does the normalized bias between observation and simulation cause? The astronomical tide level is relatively accurately simulated. And where are Stn. 20, 22, and 23? You should show in any figures. Figure 9: I seem to propagate the errors of Hs and Ts during the simulation time. Why is the error gradually larger? And please discuss how these errors propagate to the simulation of sediment transport. Figure 10: What does the contour line mean? What is DZ? Please explain more clearly in the figure caption. I don’t understand the comparison between measurement and simulation in Line 316-327. I think that you should discuss the bed changes during the three typhoons based on the measured bed changes. Why do you explain based on the simulated bed changes? Figure 11: This is the same comment. If necessary, please show it in the supplementary materials. Figure 12 and 13: It’s better to combine these figures because the difference is more clear. At present, it is difficult to understand the effect of the operation of the Amuping desilting tunnel. Figure 16: What is Qs? Figure 17 and 18: I don’t understand the difference between these figures. If you emphasize the operation effect of the Amuping desilting tunnel, you should combine these figures. Figure 19: Is panel (a) necessary? I think that there is no difference among Figure 17a, 18a and 19a. Please avoid to combine between the table and figure shown in panel (b). Figure 20: What do the red arrows mean? Figure 21: What is Qs? Where is this? Why do you show the legend arrow? I don’t the unit of sediment flux. Why is m²/s? The number character in the figure is too small.