Review Reports - Factors Influencing the Spatiotemporal Variability in the Irrigation Requirements of Winter Wheat in the North China Plain under Climate Change

Round 1

Reviewer 1 Report

Overall, this manuscript is scientifically sound and well presented. However, I have the following comments:

1. Abstract: The abstract needs to be significantly improved. Clearly highlight what is known and unknown regarding spatiotemporal variability in IR. What gaps are being addressed? Why is the research important? Why specially do the research in this region? Is there water scarcity problem in the region?

2. Title: The authors need to consider whether to include the terms "climate change' in the title. It is clear from the Abstract and the Introduction that the variability in IR being investigated is linked to climate change. I believe include of "climate change" in the title will help the readers.

3. Check lines 18-20 of page 1. Not clear what you mean by"..decreased substantially ..." Also in line 21 of page 1, clarify what you mean by "..water deficit..". Do you mean water for irrigation? What is causing the deficit?

4. Introduction: This section is well written. I note that most of the answers to the above questions are found in the Introduction. In other words, the key messages should be reflected in the Abstract.

5. This modelling done in this research covered the period 2001-2020. I wonder why the authors did not talk about the actual/real data of irrigation requirements covering this period? Are these measurements available for this region? How do they compare with the modelled data?

Author Response

Dear Reviewer 1,

Thank you for your comments on our manuscript entitled “Factors influencing the spatiotemporal variability in the irrigation requirements of winter wheat in the North China Plain”. Those comments are very helpful for revising and improving our paper, as well as the important guiding significance to other research. According to your detailed suggestions, we have made a careful revision on the original manuscript. All revised portions are marked in red in the revised manuscript which we would like to submit for your kind consideration.

Point 1: The abstract needs to be significantly improved. Clearly highlight what is known and unknown regarding spatiotemporal variability in IR. What gaps are being addressed? Why is the research important? Why specially do the research in this region? Is there water scarcity problem in the region?

Response 1: I have revised the abstract.

The evaluations were performed considering not only the combined effects of meteorological factors and phenological period, but also the various growth stages of winter wheat, which can help in making better irrigation decisions to develop targeted measures for timely water replenishment during critical periods. The North China Plain is a key agricultural production base, with 70% of the country’s wheat grown in this region. However, winter wheat is short of water in the region because rainfall is concentrated from June to October, and winter wheat grows from October to June.

Point 2: The authors need to consider whether to include the terms "climate change' in the title. It is clear from the Abstract and the Introduction that the variability in IR being investigated is linked to climate change. I believe include of "climate change" in the title will help the readers.

Response 2: Your opinion is quite reasonable. I have revised the title.

Point 3: Check lines 18-20 of page 1. Not clear what you mean by"..decreased substantially ..." Also in line 21 of page 1, clarify what you mean by "..water deficit..". Do you mean water for irrigation? What is causing the deficit?

Response 3: According to the results of significance test, wind speed and net solar radiation showed a significant downward trend (P<0.01and P<0.05, respectively, showed in Figure 2), I have revised in the paper (L22-23). The highest probability of exceedance of IR was observed in the P2 stage, I have revised in the paper (L25-26).

Point 4: Introduction: This section is well written. I note that most of the answers to the above questions are found in the Introduction. In other words, the key messages should be reflected in the Abstract.

Response 4: Thank you for your comments.

Point 5: This modelling done in this research covered the period 2001-2020. I wonder why the authors did not talk about the actual/real data of irrigation requirements covering this period? Are these measurements available for this region? How do they compare with the modelled data?

Response 5: The IR calculated in this study is the theoretical irrigation water requirements when the winter wheat reach the optimal growth condition. IR of the growth period was calculated by daily cumulative IR. However, in actual applications, winter wheat is usually irrigated 2-6 times during the crop growing season. Winter wheat is usually irrigated empirically, so there can be overirrigation or underirrigation. Therefore, IR is not suitable for strict verification and comparison with the consumption of irrigation water in actual applications. Those measurements were not available, this study aims to provide guidance and help for irrigation decision-making.

Once again, thank you very much for your constructive comments and suggestions which would help us both in English and in depth to improve the quality of the paper.

Kind regards.

Nan Wang (first author)

E-mail: 1547643865@nwafu.edu.cn

Corresponding author: Xiaoyi Ma

E-mail: xma@nwafu.edu.cn

Reviewer 2 Report

This article deals with the use of images to determine irrigation.

Some points are necessary for the authors to verify.

- Citations are outside the standard required by the journal;

- Some figures are in low resolution, making it difficult to understand.

- verify the citation correctly from the google database that was used

- the article has no discussion;

Fallow more details the manuscript.

Abstract: The summary is well written, however it lacks detailed information on how the modeling was carried out. It would also be important to contextualize the study region.

Keywords: Suggestion would be to change or insert words that are not in the abstract and title.

Introduction.: Some citations were performed incorrectly. Check journal rules. It is important in this section to seek to contextualize the work, lacking state-of-the-art information. Why this type of study? What crop is grown in the region? What models exist in the literature?
In addition, make clear the prolematics and its hypothesis.
Lino 18-30 is confused

M&M

Suggestion to better detail the models that were used. Also check how is the citation of the database that were used. In addition, I suggest improving the form of presentation of the figure, small letters make it difficult to read. Also the subtitles are not clear.
I strongly suggest that you make clear the reason for this region of the study. contextualization would be important.
What are the validation methods? Why did you use it?

Check line 130-135; 140-147; 162-166 is confused.

Results
The results are well presented, but I strongly suggest checking the image quality.
In addition, the article does not present discussions.

Lines 209-213; 222-234 Check is confused.

Describe more clearly legends of figures and tables. Insert the meanings in the legend of the figures.

Author Response

Dear Reviewer 2,

Point 1: Citations are outside the standard required by the journal.

Response 1: I have corrected it in detail as required by the journal.

Point 2: Some figures are in low resolution, making it difficult to understand.

Response 2: I have replaced the low-resolution figures with higher-resolution ones.

Point 3: Verify the citation correctly from the google database that was used.

Response 3: Thank you for your opinion, I have revised in the paper.

Point 4: The article has no discussion.

Response 4: The Discussion is ranged in 361-414 lines.

Point 5: Abstract: The summary is well written, however it lacks detailed information on how the modeling was carried out. It would also be important to contextualize the study region.

Line 18-30 is confused

Response 5: Thank you for your opinions, I have revised the Abstract.

Point 6: Keywords: Suggestion would be to change or insert words that are not in the abstract and title.

Response 6: Thank you for your opinion, I have revised the keywords in the paper.

Point 7: Introduction.: Some citations were performed incorrectly. Check journal rules. It is important in this section to seek to contextualize the work, lacking state-of-the-art information. Why this type of study? What crop is grown in the region? What models exist in the literature?

In addition, make clear the prolematics and its hypothesis.

Response 7: Due to the shortage of water resources, we should make efficient and reasonable use of water resources. And climate change inevitably affects CWR and IR, in turn, affects crop yield and quality. Therefore, this paper studied the irrigation water requirement for different winter wheat growth stages, aiming at making better irrigation decisions to develop targeted measures for timely water replenishment during critical periods (L38-39 , L52-60). Each stage of winter wheat requires different amounts of water, so the IR needs to be evaluated at different stages (L108-109). The prominent crops grown in this region are winter wheat and summer maize (L43-44). The models include crop models and the water balance model in the literature (L95-101).

Point 8: M&M: Suggestion to better detail the models that were used. Also check how is the citation of the database that were used. In addition, I suggest improving the form of presentation of the figure, small letters make it difficult to read. Also the subtitles are not clear.

I strongly suggest that you make clear the reason for this region of the study. contextualization would be important.

What are the validation methods? Why did you use it?

Check line 130-135; 140-147; 162-166 is confused.

Response 8:. I have increased the details of the model (L156-161), and also checked the citation of the database. The figures have been already modified to make it clearer. The reason for this region of the study is in 124-126 lines.

The IR calculated in this study is the theoretical irrigation water requirements when the winter wheat reach the optimal growth condition. IR of the growth period was calculated by daily cumulative IR. However, in actual applications, winter wheat is usually irrigated 2-6 times during the crop growing season. Winter wheat is usually irrigated empirically, so there can be overirrigation or underirrigation. Therefore, IR is not suitable for strict verification and comparison with the consumption of irrigation water in actual applications. Those measurements were not available, this study aims to provide guidance and help for irrigation decision-making.

Line 130-135; 140-147; 162-166 have been revised.

Point 9: Results: The results are well presented, but I strongly suggest checking the image quality. In addition, the article does not present discussions.

Lines 209-213; 222-234 Check is confused.

Describe more clearly legends of figures and tables. Insert the meanings in the legend of the figures.

Response 9: The discussion in ranged in lines 361-414. Lines 209-213; 222-234 have been revised. The figures and tables have been devised by us.

Once again, thank you very much for your constructive comments and suggestions which would help us both in English and in depth to improve the quality of the paper.

Kind regards.

Nan Wang (first author)

E-mail: 1547643865@nwafu.edu.cn

Corresponding author: Xiaoyi Ma

E-mail: xma@nwafu.edu.cn

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear editor

The authors carried out the suggestions forwarded in the initial review.