Integrative Study on Flow Characteristics and Impact of Non-Submerged Double Spur Dikes on the River System

Round 1

Reviewer 1 Report

The present work studied the flow characteristics and impact of non-submerged double spur dikes on the river system through numerical simulation and laboratory experiment. The flow structure and turbulence characteristics around dikes are analyzed, and it is found that there is an obvious turbulence accumulation effect between dikes. The criterion of spacing threshold is proposed after examining the interaction rules of non-submerged double spur dikes. The present work is of great significance to the river improvement of artificial science and the health assessment of river system under human activities. This study can be considered for publishing after addressing the following questions and comments:

1.    In lines 147-149, the dimension of models is different between the experimental and numerical ones. The authors should expound how the dimension was determined for the test model, and if there is a similarity relation for model dimension?

2.     The text in some pictures is blurred, i.e., Fig.5, Fig.6. It is recommended to replace them with high quality pictures.

3.  Figure 10, multiple curves overlapped together. It is difficult to identify the difference between the curve for s=1.5 and the curve for larger spacings. It is recommended to adjust the scale of horizontal axis to make the difference visible.   

4.     What standard did the authors consider to determine the different spacings between two spur dikes (i.e.,1.5m, 4.8m and 9m)? Is there a critical distance between the two dikes that do not affect each other?

5.  The authors should carefully check the whole article to avoid the mistakes of inconsistence font, i.e., line 25 “flume experiment”.

6.  The pictures for numerical model and complete experimental model were not presented in the article, which should be supplemented.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This paper analyzes the flow characteristics near groin fields using a 3D numerical model. In general, this paper carried out detailed measurements in the flume experiment and the simulation results of the model are reliable. However, there are some vital flaws in this paper, and the authors may resubmit it after a major revision.

1. The language issue of this paper is evident. This issue seriously affects my reading process. I hope the author can carefully revise the language of the paper, not only the grammar issues but also the academic expressions.

2. The literature reviewed in this paper is not enough. Groin fields are long-standing research objects, and there is a large amount of relevant literature. However, the literature listed in the introduction section is insufficient. For example, a large amount of research work has been conducted on the effect of groin spacing on flow fields, whereas the authors did not make a comprehensive summarization of the research.

3. The contribution of this paper is not clearly stated. This issue is related to the previous one. The authors need to carry out a comprehensive summarization of existing research and then they can pinpoint what the contribution of this study is. The authors need to clearly specify the knowledge gap of related research.

4. The numerical model part needs more details, and some key information is lacking. For example, the authors provided the total number of grids, which is not enough. The authors need to tell the reader the distribution of grids in the x y z directions, especially the grid distribution near the groins. A grid-independence test should be carried out to prove that the grid is appropriate for the simulation. The authors used a first-order upwind format, while I am not sure why such a low-precision format was used. The authors use the free outflow boundary condition, but the flume experiments are certainly not, so this is different from the actual flume boundary conditions, and the authors do not explain the effect of this treatment.

Based on the above considerations, I suggest the authors revise the manuscript carefully and then resubmit it.

Author Response

Please see attached file

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Please polish the manuscript with a native speaker or a language editing service company.

Author Response

Dear Reviewer,

Thanks for your advice. We have  polished the manuscript.