Soil and Water Losses with Simulated Rainfall Considering Experimental Plots and Rainfall Patterns

Round 1

Reviewer 1 Report

1. When introducing the experimental land, the length, width, and area of the rectangular plot used should be detailed in the same way as the circular plot

2. If each physical quantity in formula 1 has dimensions, the unit must be indicated

3. Using a beaker to measure the volume of water in the third paragraph of section 2.2 may result in lower measurement accuracy. Please supplement the reason for using a beaker instead of a measuring cylinder

4. In the sentence "models relating PI with rotation were adjusted for the two plots","two plots" should specify in detail two situations: circular and rectangular collectors

5. The depth mentioned in the fourth paragraph of section 2.2 does not specify any depth, but should be the depth of rainfall in the collector

6. The fifth paragraph of section 6.2.2 describes the depth of the soil layer. The first text is "0.0-0.34m", and the second text is "0-0.18m". The number of decimal places before and after the text should be consistent

7. The naming of soil layers in Table 1 should be explained

8. There is a cross page situation in Table 1 and Table 2. Please indicate "Continued Table" for explanation

9. Figures 5 and 6 are described in the text as "The spatial distribution of PI", but the title of the figure is " Spatial distribution of the RI". There is no explanation in the text for RI. Are PI and RI the same?

10.  What does the coefficient of variation CV reflect? How to calculate it?

11. The CV value of the coefficient of variation in Table 4 is too high, even exceeding 30%, indicating poor data stability

12.  The English alphabet in Table 4 explain that “Lowercase/Uppercase letters compare mean”,which is not clear.You can illustrate with examples what "±" ,"a", "B" and "C" in "10.6±1.2aBC" represent respectively

13. There are many English abbreviations in the article. It is recommended to explain the meaning of each English abbreviation uniformly before the article

Author Response

Thank you for comments and suggestions

1. When introducing the experimental land, the length, width, and area of the rectangular plot used should be detailed in the same way as the circular plot. This information was added in the text (lines 100-101).
2. If each physical quantity in formula 1 has dimensions, the unit must be indicated. Done (lines 114-115)
3. Using a beaker to measure the volume of water in the third paragraph of section 2.2 may result in lower measurement accuracy. Please supplement the reason for using a beaker instead of a measuring cylinder. Thanks for the comment. In fact, we use a graduated cylinder with a measuring scale of 1.0 mm. Therefore, there was no lack of precision in the measurement. (lines 123-124).
4. In the sentence "models relating PI with rotation were adjusted for the two plots","two plots" should specify in detail two situations: circular and rectangular collectors. Done (line 127)
5. The depth mentioned in the fourth paragraph of section 2.2 does not specify any depth, but should be the depth of rainfall in the collector. The expression “depth of 30 mm” was removed from the text as it is not essential. In fact, an event with a PI of 45 mm h^-1 and a duration of 40 min represents a depth of rainfall of 30 mm (line 135).
6. The fifth paragraph of section 6.2.2 describes the depth of the soil layer. The first text is "0.0-0.34m", and the second text is "0-0.18m". The number of decimal places before and after the text should be consistent. Ok. The text was changed on line 151 and in Table 1.
7. The naming of soil layers in Table 1 should be explained. Thanks for the comment. According to Pedology experts, the subdivision of horizons is very variable and depends on the combination of a lot of information. We added information in Table 1 as a footnote, citing the Brazilian Soil Classification System (Santos et al., 2018) (line 166). Basically, A and B refer to the surface and subsurface horizons, respectively. The Ap horizon is one that has been altered by anthropogenic actions (mechanization), while the Bt horizon represents clay accumulation.
8. There is a cross page situation in Table 1 and Table 2. Please indicate "Continued Table" for explanation. We understand that this formatting issue is the responsibility of the journal's editorial team. In any case, we chose to change the position of the text to avoid page breaks in the tables.
9. Figures 5 and 6 are described in the text as "The spatial distribution of PI", but the title of the figure is " Spatial distribution of the RI". There is no explanation in the text for RI. Are PI and RI the same? Exactly. There was a mistake and the text was corrected for PI. Thanks for the observation (lines 216 and 219).
10. What does the coefficient of variation CV reflect? How to calculate it? CV is a measure of the dispersion of a data set and is calculated as the ratio between the standard deviation and the mean of the data.
11. The CV value of the coefficient of variation in Table 4 is too high, even exceeding 30%, indicating poor data stability. Thanks for the comment. However, this existing variation is related to the natural variability of soils and does not compromise the quality of the data obtained. It is common to find CVs even higher than these.
12. The English alphabet in Table 4 explain that “Lowercase/Uppercase letters compare mean”,which is not clear.You can illustrate with examples what "±" ,"a", "B" and "C" in "10.6±1.2aBC" represent respectively. In our study, two experimental plots and 4 precipitation patterns were evaluated. According to the note below the Table, the lowercase letter compares the runoff and soil loss values between the two plot formats, for the same pattern (evaluation on the line). The Uppercase letter refers to the comparison of values between precipitation patterns, for the same experimental plot (evaluation in the column). The expression "±" represents the variation of the data around the average value (more or less). It is a very common way of presenting experimental data. The value 10.6±1.2 aBC means that the soil loss in the circular plot and in the delayed pattern was 10.6 g m^-2, with a variation of more or less than 1.2 g m^-2. This value is statistically equal to the value found in the rectangular plot (14.1±7.5) (letter a) and lower than the soil loss obtained in the Advanced pattern (letter A), but similar to the values obtained in the Intermediate (letter B) and constant (letter C) patterns. In the footnote of Table 4, the terms "depth and soil loss" were added for better understanding by readers (lines 237-238).
13. There are many English abbreviations in the article. It is recommended to explain the meaning of each English abbreviation uniformly before the article. Abbreviations are always displayed when they first appear in the text. We thought it was better to use them so that the expressions didn't become too repetitive. Explanation of the meaning of each abbreviation before the text is a criterion of the journal's editing department, and we can make a consultation. Thanks

All comments were important and we included those we considered most relevant in the text. Thank you very much for reviewing our manuscript.

Reviewer 2 Report

The paper is fine

I suggest reading the key papers by Professor Cerdà about rainfall simulations

see here

Cerdà, A., Rodrigo-Comino, J., Giménez-Morera, A., Novara, A., Pulido, M., Kapović-Solomun, M., & Keesstra, S. D. (2018). Policies can help to apply successful strategies to control soil and water losses. The case of chipped pruned branches (CPB) in Mediterranean citrus plantations. Land Use Policy, 75, 734-745.

Cerdà, A., Rodrigo-Comino, J., Yakupoğlu, T., Dindaroğlu, T., Terol, E., Mora-Navarro, G., ... & Vaverková, M. D. (2020). Tillage Versus No-Tillage. Soil Properties and Hydrology in an Organic Persimmon Farm in Eastern Iberian Peninsula. Water, 12(6), 1539.

Author Response

Thank you for indicating the texts. The articles are very interesting and aimed at simulated rain, but their objectives are: to assess the effects of chipped pruned branches on soil and water losses after a decade of CPB cover in citrus orchards; and to determine the impact of No-Tillage on organic farms (with weed cover) in controlling soil and water losses in areas that were previously tilled.

These topics are very important but they do not concern our research, which evaluated the effect of precipitation patterns and the shape of the experimental plot on soil erosion, in an area without soil cover. It is worth mentioning that we used 3 other articles by Professor Cerdà in our text [5, 11, 30].

Thank you very much for reviewing our manuscript.

Reviewer 3 Report

Dear Authors, 
Please find my comments in the attached file.

Comments for author File: Comments.pdf

Author Response

Thank you for comments and suggestions.

Specific comments

1. What is the main objective of the study? This is not clearly specified in the text. The objective of the research is presented in lines 78-80. In any case, we added the expression “main” (line 79) and we added the text in lines 82-84, characterizing the secondary objectives.
2. What was the duration of simulated rainfalls? Was it always the same (40 minutes) or does it change for different tests? It is not clearly said in the text. Exactly. The duration of simulated rain was always the same for all precipitation patterns evaluated (40 min). This information is present in lines 135, 194, 205, 236, and 242.
3. What was the soil moisture content before the simulated rainfall occurred? Thanks for the comment. Without a doubt, the soil moisture content before the rain is one of the main factors that influence the infiltration process and, consequently, surface runoff, in addition to the stability of soil aggregates. The natural soil moisture before the tests varied, considering the meteorological conditions in the region. However, in order to standardize the moisture conditions before the tests, the experimental plot was always pre-wetted. This information is presented in lines 156-159.
4. Do you have the information about kinetic energy of the raindrops? Yes, and this is a very important characteristic that rain simulators must present: simulated rainfall kinetic energy similar to that of natural rain. InfiAsper is frequently evaluated for droplet diameter, kinetic energy and erosivity of the rain being simulated. In this study, the average kinetic energy, considering the constant pattern (CT) (45 mm h^-1), was 16,81 J m^-2 min^-1, 87% similar to natural rain, according to the computational routine proposed by Alves Sobrinho et al. (2008). For patterns with variable PI, the kinetic energy varied from 11.20 J m^-2 min^-1 (30 mm h-1) to 41.08 J m^-2 min^-1 (110 mm h^-1) (Figure 4). This information was added in lines 137-139.
5. How many simulations under the each plot did you take in total? Was it always in this same conditions? The simulations were always carried out in independent plots, that is, the equipment was changed position for each simulated rain event. To meet the statistical design, rainfall was simulated in 32 positions (lines 152-155).
6. The title of the article suggests, that it also contains information on soil erosion. However, I have the impression that the weight of the information contained in it is focused on the characteristics of the simulated rain. The loss of soil is less prominently featured, although it comes first in the title. The results of soil losses should be more widely commented and discuss. We appreciate your comment, but we understand that the title can be presented in different ways and, certainly, different opinions can arise. The main focus of the study was to evaluate soil and water losses from different experimental plots and precipitation patterns. As for patterns, our research group has been working for some time and we have published information, including those cited in the text (Carvalho, D.F.; Macedo, P.M.S.; Pinto, M.F.; Almeida, W.S.; Schultz, N. Soil loss and runoff obtained with customized precipitation patterns simulated by InfiAsper. International Soil and Water Conservation Research 2022, 10, 407–413. https://doi.org/10.1016/j.iswcr.2021.12.003; Macedo, P.M.S.; Pinto, M.F.; Alves Sobrinho, T.; Schultz, N.; Coutinho, T.A.R.; Carvalho, D.F. A Modified portable rainfall simulator for soil erosion assessment under different rainfall patterns. Journal of Hydrology 2021, 596, 126052. https://doi.org/10.1016/j. jhydrol.2021.126052). However, InfiAsper had not yet been used with a circular plot, which required complete characterization before starting field tests. Therefore, the text was divided into several items (3.1,....,3.4), representing the sequence in which the data was obtained, initially in the laboratory. After hydraulic characterization, field tests were carried out, making it possible to obtain soil and water losses. We understand that the field information/data is properly presented. Thanks for the comment.
7. Soil microrelief, as same as vegetation cover, has an impact on infiltration and water erosion. Did you consider this?  These characteristics certainly influence the infiltration and soil erosion processes. However, as mentioned, the objective of this study was to evaluate the effect of precipitation patterns and experimental plot shape on soil erosion. For this reason, ground surface conditions were kept uniform for all tests.
8. How the  results  of  your  work  can  be  used  in  the  practice  of  soil  erosion protection? Thanks for the question. The objective of this study was to evaluate the effect of precipitation patterns and the shape of the experimental plot on soil erosion, and not to propose soil management and conservation practices in order to protect it against erosion. The question is pertinent but was not part of our objective.

I think the above information should be included in the text. All comments were important and we included those we considered most relevant in the text. Thank you very much for reviewing our manuscript.