Influence of Subsoiling on the Effective Precipitation of Farmland Based on a Distributed Hydrological Model

Round 1

Reviewer 1 Report

Authors have addressed all points raised by me and the quality of the manuscript has been improved.

There are some minor editorial errors and author’s can get a support from a third party person to read it and get corrected those errors. Such as “water holding” VS “water-holding”

 

Some additional comments are;

Line 36-37: “leakage” and “deep leakage” is not technical terms in soil hydrology. Use “percolation” and “deep percolation” or any other commonly use technical term.

Line 40: “cropland structure” – what is this?

Line 44: land cover on soil water “permeability” or “infiltration”?

Line 53-54: “Soil plays an important role in the utilization of farmland precipitation” – a very general statement and not suitable here. Better to move to the initial paragraph or modify this sentence to be more specific.

Line 160: “The effect of subsoiling on the soil pore structure mainly increases soil capillaries”- this is not always correct. Subsoiling some times increase macropores and then reduces capillary. Capillary can be increased by increasing micropores.

Line 161: “strengthens soil permeability” – what is meant by strengthen? Or “increases”?

Line 164: “0-300 cm” or is this “0-30 cm”?

Line 195: “vertical model” – 1D model?

Line 205: “did not change significantly” – did you do the statistical analysis? If yes, give the “P” value here.

Line 208: “did not change significantly” – same comment as above.

Authors use “did not change significantly” in different places. I do not see any statistical analysis to use term “significant”. How do you know whether it is significant or not without doing statistical analysis?

Authors use “farmland runoff” – but Figure 6 has “Agriculture runoff”?

It is a good contribution for readers of the journal and I would like to congratulate authors.

Author Response

Thanks for your detailed comments on our paper. Your suggestion makes our paper more perfect. We revised the paper according to your comments. The revisions are listed as follows:

1. There are some minor editorial errors and author’s can get a support from a third party person to read it and get corrected those errors. Such as “water holding” VS “water-holding”

Reply:

We consulted scholars of soil hydrology and consulted relevant literature. Make sure that the more academic expression is water-holding capacity. Therefor, we changed the water holding capacity in the text to water-holding capacity. The modified part has been highlighted in yellow.

2. Line 36-37: “leakage” and “deep leakage” is not technical terms in soil hydrology. Use “percolation” and “deep percolation” or any other commonly use technical term.

Reply:

According to the opinion, we changed the leakage to percolation.

3. Line 40: “cropland structure” – what is this?

Reply:

By consulting the original reference, the corrected word is land resources utilization.

4. Line 44: land cover on soil water “permeability” or “infiltration”?

Reply:

Land cover affects the soil surface, so it is infiltration. Therefor, we have made corresponding change in the new manuscript.

5. Line 53-54: “Soil plays an important role in the utilization of farmland precipitation” – a very general statement and not suitable here. Better to move to the initial paragraph or modify this sentence to be more specific.

Reply:

We moved the sentence to the introduction section, the second sentence of the second paragraph. As shown in line 36 of new manuscript.

6. Line 160: “The effect of subsoiling on the soil pore structure mainly increases soil capillaries”- this is not always correct. Subsoiling some times increase macropores and then reduces capillary. Capillary can be increased by increasing micropores.

Reply:

The explanation you said made me learn a lot. It was my mistake. What I want to write was soil porosity. The final sentence should be “The effect of subsoiling on the soil pore structure mainly increases soil porosity, …”

7. Line 161: “strengthens soil permeability” – what is meant by strengthen? Or “increases”?

Reply:

What I want to express is the meaning of increase. The correct statement is: increases soil permeability.

8. Line 164: “0-300 cm” or is this “0-30 cm”?

Reply:

We checked the literature, the expression in the original text is: 0-300cm.

9. Line 195: “vertical model” – 1D model?

Reply:

I guess your doubt is the “verified model”. This is because we constructed and verified the WEP model in the study area in section 2.3. The verified model was used for scenario simulation, in section 2.4. In order to make the expression clearer, we added the word WEP. As shown in the new manuscript.

10. Line 205: “did not change significantly” – did you do the statistical analysis? If yes, give the “P” value here.

Line 208: “did not change significantly” – same comment as above.

Authors use “did not change significantly” in different places. I do not see any statistical analysis to use term “significant”. How do you know whether it is significant or not without doing statistical analysis?

Reply:

At the beginning of this article, there was no statistical analysis, and the conclusion was obtained through observation. After your reminder, I realized that I was not rigorous in scientific research. Therefore, we did the significance test. We used a one-way analysis of variance with a confidence of 0.05. The calculated result P was 0.99, indicating that the simulation results of surface runoff (P3 vs P1 and P4 vs P2) and evapotranspiration (P3 vs P1, P4 vs P2 and P5 vs P3) were the same. So, we use did not change instead of did not change significant. In other words, we deleted the word: significant.

11. Authors use “farmland runoff” – but Figure 6 has “Agriculture runoff”?

Reply:

We have corrected the Agriculture runoff in Figure 6 to Farmland runoff.

Author Response File: Author Response.pdf

Reviewer 2 Report

The Authors have made significant improvements in the resubmitted version of the manuscript. Also their explanations to the reviewers remarks are satisfactory. It is recommended to accept the paper for publication in present form.

Author Response

Thank you for your recognition and encouragement, we will continue to work hard.

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

The paper analyzes effects of subsoiling on changes in distribution of precipitation with the use of a distributed hydrologic model. In my opinion the submission is interesting and deserves attention. However, there exist shortcomings, which require improvements prior to its final acceptance for publication. They are as follows:

1. Location of the study area in Shandong province and in China, respectively, should be shown on additional maps.
2. P. 2, l. 74-75: “The Sihe River, which ORIGINATED (…)”. Does it mean that the river is dried up and does not run water any longer? Please explain.
3. P. 2, l. 79 and Figure 1: elevations should be expressed in meters above sea level (m a.s.l.). Please correct.
4. As the Authors underline in “Abstract”, precipitation is crucial for the crop growth. So, please add more detailed information on the climate of the study area with special regard to precipitation and its seasonal distribution.
5. Data source: what is the time step (daily, monthly or other) of the analyzed data sets? Please specify.
6. Table 1: The scenarios P1-P6 need to be described in a more detailed way, preferably in a separate sub-chapter.
7. P. 5, l. 144: “…” and the years 1968-1995 were selected as the calibration period and 1991-2015 as the verification period of the model”. Figure 6 and Table 2 show that the calibration period is 1968-1990, so please check the correctness of that sentence.
8. The figures presented in the paper are too small and thus hardly readable. They need to be enlarged.
9. The figure captions are not informative and need to be corrected. It is also strongly recommended not to split figures, as for example “Fig. 8(a)”, “Fig. 8(b)”, “Fig. 8(c)”, but rather describe them as: “Figure 8. Results of…: (a) surface runoff, (b) evapotranspiration, (c) agriculture runoff”.
10. The “Conclusions” chapter needs to be enlarged. Alternatively, it can be merged into one chapter with “Discussion”.

Author Response

Thanks for your detailed comments on our paper. Your suggestion makes our paper more perfect. We revised the paper according to your comments. The revisions are listed as follows:

1. Location of the study area in Shandong province and in China, respectively, should be shown on additional maps.

Reply:

The location of the study area in Shandong province and in China has been shown in Fig. 2 in the new manuscript.

2. 2, l. 74-75: “The Sihe River, which ORIGINATED (…)”. Does it mean that the river is dried up and does not run water any longer? Please explain.

Reply:

The river has not dried up, and there has been water in it all the time. The word ORIGINATED means to describe the origin or source of the river.

3. 2, l. 79 and Figure 1: elevations should be expressed in meters above sea level (m a.s.l.). Please correct.

Reply:

The Figure 1 has been corrected.

4. As the Authors underline in “Abstract”, precipitation is crucial for the crop growth. So, please add more detailed information on the climate of the study area with special regard to precipitation and its seasonal distribution.

Reply：

The climate information of the study area has been added to research area part (section 2.1) of the article.

5. Data source: what is the time step (daily, monthly or other) of the analyzed data sets? Please specify.

Reply:

The time step  is daily. We have specified in the data source part (section 2.2) of the article.

Daily data of three meteorological stations (Fig. 3(e)) (including stations around the basin) were collected from 1968 to 2015, including wind speed, temperature, illumination time and relative humidity data, which comes from the National Meteorological Information Center.

6. Table 1: The scenarios P1-P6 need to be described in a more detailed way, preferably in a separate sub-chapter.

Reply:

In order to better describe the scenarios p1-p6, we adjusted the position of Table 1 and explained the basis and function of the scenarios setting, as shown in section 2.4.2 of the article.

7. 5, l. 144: “…” and the years 1968-1995 were selected as the calibration period and 1991-2015 as the verification period of the model”. Figure 6 and Table 2 show that the calibration period is 1968-1990, so please check the correctness of that sentence.

Reply:

There was something wrong with the writing. We have corrected the sentence and revised the corresponding sentence in the article. The correct sentence is “…” and the years 1968-1990 were selected as the calibration period and 1991-2015 as the verification period of the model.

8. The figures presented in the paper are too small and thus hardly readable. They need to be enlarged.

Reply:

We have modified the size of the picture to ensure that the reader can read it easily.

9. The figure captions are not informative and need to be corrected. It is also strongly recommended not to split figures, as for example “Fig. 8(a)”, “Fig. 8(b)”, “Fig. 8(c)”, but rather describe them as: “Figure 8. Results of…: (a) surface runoff, (b) evapotranspiration, (c) agriculture runoff”.

Reply:

We have corrected the captions and layout of figures.

10. The “Conclusions” chapter needs to be enlarged. Alternatively, it can be merged into one chapter with “Discussion”.

Reply:

We modified and expanded the results according to the research objectives and results.

Author Response File: Author Response.pdf

Reviewer 2 Report

Very interesting piece of work based on the scenario analysis through a modeling exercise. Authors tried to understand/explain what would happen to soil hydrology and therefore effective precipitation when sub-soiling is introduced. This would be a good paper for readers of the journal, but there are some confusing points, structure, methodology and discussion. Therefore, before recommendation for publication, I think authors should re-structure and re-write the manuscript, avoid repetitions.

All my major and minor comments are given in the annotated manuscript and few major points are given below;

 

Methodology section is not clear and confusing. Especially with respect to Table 1 and setting for Scenario Analysis. Need to clearly give the theoretical justification. Basic soil properties are not given (or have I missed those?)

 

Lines 186-247: I think too much information here;

1. some points can go to the background justification- Introduction
2. some points can be used in discussion
3. some points can be deleted since they are very general.
4. then reduce the content here to the most important for selecting your scenario analysis.

 

Surface runoff, watershed runoff, agriculture runoff, farmland runoff is confusing terms used. Need to very clearly give what is meant by each term and what they represent.

 

Think of reorganizing Figures 1~4 as one figure

Hope these points and comments/suggestions given in the manuscript would help to improve it.

All the best

Comments for author File: Comments.pdf

Author Response

We have learned much from the comments, which are fair, encouraging and constructive. After carefully studying the comments and your advices, we made corresponding changes.

We have modified the abstract, introduction, material and methods, results, discussion and conclusion. The details are shown below and highlighted in yellow in the manuscript:

Abstract:

1. “…on local precipitation efficiency of the basin scale”. The sentence was intended to express the effective precipitation in the basin. So, we revise the sentence to “…on effective precipitation of the basin”
2. “soil ploughing layer” refers to the part of the soil layer that can be used for crop cultivation. It is different from “sub-soiling” and the layered structure of the soil was shown in Fig. 5 in the new manuscript.
3. We have deleted the sentence “Considering the changes of all factors, the results showed that subsoiling not only improved the effectiveness of local precipitation but also reduced the runoff of farmland”.

Introduction:

1. “precipitation effectiveness” is the same as “effective precipitation”. We changed “precipitation effectiveness” to “effective precipitation”
2. We re-read the reference and revised the sentence to make it clear. We changed “The Budyko framework was integrated into the traditional crop coefficient approach to simplify the coefficients of determination and calculated the crop evapotranspiration” to “The Budyko framework, which was used to explore the relationship between crop evapotranspiration and regional total evapotranspiration in regional water-energy balance, was applied to access virtual water content of agricultural crops”
3. “The effect of soil tillage and land cover on soil water infiltration was evaluated by measuring this parameter in areas under bare soil, soybeans”. “this parameter” refers to “water infiltration”. The word “this parameter” make the sentence confused. So, we deleted it. The final sentence: The effect of soil tillage and land cover on soil water infiltration was evaluated in areas under bare soil, soybeans (conventional tillage and no-tillage) and pasture.
4. “the relationship between the subsoiling and precipitation”. This sentence is likely to express the qualitative effect of subsoiling on effective precipitation, positive or negative? The article expresses the process from qualitative to quantitative. So, we revised the sentence to that “Two problems are observed: qualitative effect of subsoiling on effective precipitation and quantitative effect of subsoiling on soil properties and their impact on the effectiveness of precipitation.”

Material and methods:

1. About Table 1. In order to describe the scenarios p1-p6, we adjusted the position of Table 1 and explained the basis and function of the scenarios setting, as shown in section 2.4.2 of the article.
2. “underlying surface” is a hydrology vocabulary, which represents the interface between the atmosphere and the solid ground or liquid water surface. It is a general term for all coverings on the ground, such as cultivated land, forest, grass, water bodies, buildings etc.
3. We have changed “verification” to “validation”
4. The “correlation coefficient” is for the relationship between measured surface runoff and predicted one. The measured surface data comes from the hydrological station, which was the actual flow data after human beings draw water from the river. Based on the measured data, we restore the river water intake data of the river and deserve the natural runoff. The result of the model simulation is the natural runoff, without considering the influence of human water intake. We calculate the correlation coefficients between the simulation results of the model and the measured runoff to indicate whether the model simulation results are good or bad. There are two reasons why the two series will not show a linear relationship at 1:1. One is the basic data. It is uncertain whether restoration of measured data of hydrological stations is the runoff data that should be available without human activities. However, the result of model simulation is the runoff process without human activity. Therefore, the simulation results and the measured data are difficult to form a 1:1 relationship. The second is that the current hydrological cycle in the model is not exactly the same as the actual situation. Two uncertain factors result that the relationship between the measured data and the simulated data is not 1:1.
5. “Fig 7. The effect of subsoiling on soil structure”. This picture is a brief display of the effects of subsoiling on the plough layer. This article mainly studies three aspects: the thickness of plough layer, the saturated soil moisture content and the infiltration rate. So, we have revised the diagram and renamed it.

Results:

1. The difference between surface runoff and agriculture runoff. There are different surface types in the basin, such as forest, grassland, cultivated land, etc. The surface runoff refers to runoff generated by rainfall in the whole basin. The agriculture runoff refers to the runoff generated by rainfall in areas where the surface is cultivated land. Agriculture runoff is part of surface off. Their schematics were shown in Fig. 6 in the new manuscript.
2. In 3.2, 3.3 and 3.4 sections, we described in detail the basis of the scene setting in section 2.4.2 and adjusted the position of Table 1. This study is mainly to study the effect of subsoiling on effective precipitation caused by the change of soil characteristics (thickness, saturated water content and infiltration rate). According to the literature survey, two sets of comparison scenarios were set for each element. The results of section 3.1, 3.2 and 3.3 were simulation results of the comparison of each element scenario. Section 3.4 was a comparative scenario where all three elements have changed.
3. We have unified the Y-axis of all the figures in the results section.

Discussion:

According to the opinion, we have revised the unclear expression in the discussion and deleted words that were not useful in the text.  

Conclusion:

We have improved conclusion, according to the objectives of the paper.

Reply to specific comments：

1. Methodology section is not clear and confusing. Especially with respect to Table 1 and setting for Scenario Analysis. Need to clearly give the theoretical justification. Basic soil properties are not given (or have I missed those?)

Reply:

At the beginning of the methodology section, we added a paragraph to explain the structure and analysis process of the article. We adjusted the Table 1 and explained the detailed process of the scenarios setting, as shown in section 2.4.2 of the article.

Basic soil properties have been given in the section 2.1.

2. Lines 186-247: I think too much information here;

• some points can go to the background justification- Introduction
• some points can be used in discussion
• some points can be deleted since they are very general.
• then reduce the content here to the most important for selecting your scenario analysis.

Reply:

According to the comments, we have revised lines 186-247. In this part, we mainly deleted. What we deleted is to introduce other scholars to the experiment process. Because this part has little relevance to this article. Our main concern is the methods and conclusion of other scholars.

3. Surface runoff, watershed runoff, agriculture runoff, farmland runoff is confusing terms used. Need to very clearly give what is meant by each term and what they represent.

Reply:

According to the comments, we have explained each term. As show in section 2.4.3.

4. Think of reorganizing Figures 1~4 as one figure.

Reply:

We have combined Figures 1~4 as a new figure 3 in the new manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

While the Authors have made some corrections in the submission, some minor shortcomings still require improvements. These include:

1. Figure 2: two separate scale bars should be drawn on the newly added maps showing the location of the study area in Shandong province and the investigated watershed, respectively (the two rectangle maps on the right side of the map of China.
2. P. 2, l. 80: “The Sihe River, which ORIGINATED (…)”. Does it mean that the river is dried up and does not run water any longer? Or maybe this is only a language error and it should be written “ORIGINATES”? Please explain.
3. P. 3, l. 91-92: elevations should be expressed in meters above sea level (m a.s.l.), NOT IN METERS. Please correct.
4. Figure 3a (Legend): elevations should be expressed in meters above sea level (m a.s.l.), NOT IN METERS. Please correct.

Author Response

Thanks again for your patient comments and guidance. Your suggestion makes our paper more perfect. We revised the paper according to your comments. The revisions are listed as follows:

1. Figure 2: two separate scale bars should be drawn on the newly added maps showing the location of the study area in Shandong province and the investigated watershed, respectively (the two rectangle maps on the right side of the map of China.

Reply：

According to the opinion, we have made corresponding changes to Figure 2. As highlighted in yellow in the new manuscript.

2. 2, l. 80: “The Sihe River, which ORIGINATED (…)”. Does it mean that the river is dried up and does not run water any longer? Or maybe this is only a language error and it should be written “ORIGINATES”? Please explain.

Reply：

I am very sorry for my language error. I didn’t accurately understand what you mean last time. The river has not dried up, and there has been water in it all the time. The correct word is “ORIGINATES”. And we have modified this word in the new manuscript.

3. 3, l. 91-92: elevations should be expressed in meters above sea level (m a.s.l.), NOT IN METERS. Please correct.

Reply：

According to the comment. We have made corresponding corrections.

4. Figure 3a (Legend): elevations should be expressed in meters above sea level (m a.s.l.), NOT IN METERS. Please correct

Reply：

According to the opinion. We have corrected the Figure3a(Legend).

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have addressed all comments and suggestions given and the manuscript has improved substantially. I would like to congratulate the authors.

A couple of minor points though;

1. The authors have included a new section to explain the scenario analysis related to Table 2. Here they use smaller case p [p1~p6] where has other places including in the table, they use upper case [P1~P6]. This has to be corrected.

 

2. Use of fundamental terms related to “Effect of sub-soiling on saturated moisture content and infiltration”

The main scenario is “saturated moisture content” and the author’s found this as the most effective parameter. I think this should be “porosity”. I know authors have assumed when the soil is saturated, the moisture content is equal to the porosity. That is fine and is a fundamental characteristic. However, especially with respect to this experiment of infiltration and water holding capacity, this has to be very carefully used.

1. a) When your infiltration under saturated moisture content is considered, that is the lowest infiltration rate (basic infiltration rate). When soil is dry (not saturated) infiltration rate is high (initial infiltration rate) and will decrease with time.
2. b) On the other hand, when porosity increases, infiltration, and water holding capacity within the soil profile increase. That is the main idea of this experiment as well.
3. c) Saturated moisture content is a temporary factory (temporally variable) and porosity is not that time-sensitive (depends on the bulk density) unless compaction or tillage occurs (temporally stable – at least for the short term).

Therefore, I would like to recommend using “porosity” instead of “saturated moisture content”. If you decide to change, make sure to change in Table 2, Abstract and Conclusion as well.

Author Response

Thanks again for your patient comments and guidance. Your suggestion makes our paper more perfect. We revised the paper according to your comments. The revisions are listed as follows:

1. The authors have included a new section to explain the scenario analysis related to Table 2. Here they use smaller case p [p1~p6] where has other places including in the table, they use upper case [P1~P6]. This has to be corrected.

Reply:

We have changed all smaller case p [p1~p6] to upper case P [P1~P6]. At the same time, we have changed “original” to “Original” to make the scenario name in the text consistent with the table.

2. Use of fundamental terms related to “Effect of sub-soiling on saturated moisture content and infiltration” The main scenario is “saturated moisture content” and the author’s found this as the most effective parameter. I think this should be “porosity”. Therefore, I would like to recommend using “porosity” instead of “saturated moisture content”. If you decide to change, make sure to change in Table 2, Abstract and Conclusion as well.

Reply：

Thanks for your patience to explain the meaning and physical process of “saturated moisture content” and “porosity”, which has made me learn a lot. I very much agree with you. Replacing “saturated moisture content” with “porosity” will make this article more reasonable and meaningful. Therefor, we have made corresponding changes in the text and highlighted it in yellow.

Author Response File: Author Response.pdf