Dynamics of Volumetric Moisture in Sand Caused by Injection Irrigation—Physical Model
Round 1
Reviewer 1 Report
The idea of the study is about high-pressure subsoil irrigation, which I have not heard before. The cited literature regarding this topic is also from the same authors from 2013 but unfortunately unavailable for me (incorrect ISBN number). Thus I can not judge the relevance of this method. In addition, some other key references are in Polish and therefore also unavailable for the reader.
I think the introduction is too long. It reviews the practical aspects of injection irrigation. In contrast, the study aims to investigate water dynamics in pure sand. Sand is a simple and easy to model system, even though it is far from real aggregated soil. Accordingly, if the injection method is in a field trial phase, the water movement in pure sand is without relevance; otherwise, if the method is not tested yet, please rewrite the introduction.
The authors are writing about soil along the study, however, the applied sand is not soil.
The methods chapter is also long, even though it does not contain information regarding crucial questions. It is not clear, for example, how the monolith was constructed. Is it a natural monolith, or some sand compacted? How is it stored? In a closed flume with no air movement thru the sides? How were the sensors placed in their right position? How did this process not affected the structure of the monolith? How many monoliths were measured? Was each replication in a separate monolith? Nothing is given about the porosity of the monolith. A bulk density value is cited for coarse sand, which is not comparable with the present case.
The presented values are single numbers. I have no idea what the mentioned replications used for? Some results are presented as a finding of a single volume injection. But nothing is presented regarding the other volumes.
I am not quite sure whether 11 figures are really needed for such a study to present.
My additional comments and questions are in the attached text.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
thank you for your comments. We made every effort to include each of the remarks. Each of the comments improved the quality of the manuscript. In the attachment we present the responses to individual comments.
Authors of "Dynamics of volumetric moisture in a sandy soil caused by injection irrigation – physical model"
Author Response File: Author Response.pdf
Reviewer 2 Report
This manuscript describes the results of a laboratory experiment in which a volume of water was injected at a point under high pressure into a sandy soil block. The results demonstrate how the injected water redistributes within the soil block following injection. This work has practical implications for the design and use of injection systems for the irrigation of row crops.
I found this paper to be interesting and it would likely be of interest to readers of Water. The paper is well written, but in my opinion is much too long. The paper is structured and reads like a research project report rather than a research paper for a professional peer-reviewed journal. I suggest that the manuscript be condensed significantly to clearly present the experimental setup and the results. The contribution of this paper is a well-designed experimental setup and results depicting the redistribution of moisture following injection. With a focus on these contributions, the paper would be much easier to read and follow and would get higher readership.
The excellent water balance immediately following injection indicates that the experimental setup is well designed in terms of sensor spacing and accuracy. The long-term decline in the calculated water content of the experimental soil block though raises issues regarding the experimental design. I think the discussion of this issue should be simplified and clearly hypothesized to be due to sensor density in deeper horizon. It should be clearly noted that this issue does effect that results observed in terms of moisture redistribution in early time following injection.
I only have some minor comments on content.
- Consistency in use of “.” and “,”. For example on lines 230-232 both “28.29” and “28,29” are used in referring to the same value.
- The abbreviation “e.g.” meaning “for example” in my opinion is overused in the manuscript. In many contexts within the manuscript I think it could be deleted.
- Lines 308-310 and elsewhere it is implied that the Richard’s equation is a numerical method. It should be clearly stated that numerical methods are used to solve differential equations such as the Richard’s equation.
- Lines 88-89 --- not clear what processes are not included in Richard’s equation. I would think that main process not included is soil structure deformation.
- Line 298 “od” should be “of”
- Line 304, not clear where elementary volumes should have identical dimensions. If they do not, simple correction to account for differences in volumes among the elementary volumes.
- Lines 512-513. I would think a potential causes of the relative error of mass balances is the potential error in the amount of injected water.
Author Response
Dear Reviewer,
thank you for your comments. We made every effort to include each of the remarks. Each of the comments improved the quality of the manuscript. In the attachment we present the responses to individual comments.
Authors of "Dynamics of volumetric moisture in a sandy soil caused by injection irrigation – physical model"
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors addressed most of my comments thus, the article was improved relevantly. However, the title still refers to the investigation made in "soil" instead of the pure sand.
But my biggest concern is about the lack of replications. The whole study reports the result of a single measurement even though the abstract promises results regarding various water quantities. Scientifically, a single experiment without replications and, therefore, estimation on errors is not relevant.
Author Response
Dear Reviewer,
we would like to thank you for Review Report (round 2). According to your comments, we have removed “soil” from the title of the manuscript. In the abstract, we have exchanged “soil” for “sand”, “sand monolith” and “porous material”.
The scope of the experiment did not include repetitions of the same water doses injections. Undoubtedly, such repetitions would be very valuable and would improve the quality of the work. In our opinion, it is very important, but not crucial. The water balance calculations demonstrate that the planned methodology and execution each of the experiments were accurate. Moreover, the ratios between the injected water and the intensity of volumetric moisture changes are noticeable. The higher water dose, the more significant the volumetric moisture changes. It was shown in figures 7 and 8, as well as it was mentioned in the text of the manuscript. We would like to emphasize that this is a preliminary study whose results could provide a basis for verification and validation of a numerical model describing water movement in a porous medium under injection irrigation conditions. Therefore, in our opinion, the research design enabled achieving the research objectives.
Yours sincerely,
Amadeusz Walczak
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors appropriately modified the manuscript in response to my initial comments. In my opinion, the manuscript is acceptable.
Author Response
Dear Reviewer,
we would like to thank you for your valuable review. As we mentioned, your comments have significantly improved the quality of the manuscript.
Yours sincerely,
Amadeusz Walczak
