Simulation Study on Water Quality of Paddy Field Ditches Considering the Effects of Rainfall and Sediment Release
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors, please see the recommendations in the attachment.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors! I with interest read your manuscript entitled: “Simulation Study on Water Quality of Rice Field Ditches Considering the Effects of Rainfall and Sediment Release”. The topic of article is actual and fits to Sustainability journal scope. Also the paper is suitable for consideration in other MDPI journals like Land, Water, Hydrology, etc. I have the following comments and recommendations:
1. Abstract is OK.
2. In Keywords better avoid “words” which already were mentioned in the Title of article, also please reduce the length some of “keywords” (now some of them looks like sentence).
3. L. 40. runoff/erosion induced by rainfall.
4. “TP” here provide full name of abbreviation or add on L. 42 total phosphorus (TP). What the maximum permissible level of nitrogen and phosphorus concentrations?
5. Please revise sentence LL. 46-49.
6. L. 76. 50 а? what a unit?
7. L. 163. Please check correctness of unit (kg/hm2).
8. In section 2.1. I suggest to add climatic data of study area (temperature, etc.) More attention please give about rainfalls. What an average annual amount of precipitations, what type of them (rain or snow), what is an intensity and amount of rainfalls in months. What a soil type and short description of their properties.
9. Fig. 1. Suggest also indicate where the study area located within China.
10. I suggest read the article about pollutant (Cs) migration during erosional runoff events (“Siltation and radiocesium pollution of small lakes in different catchment types far from the Fukushima Daiichi nuclear power plant accident site”); it related to your research and could be useful to you as well could improve the Introduction section.
11. L. 302. “rate of degradation of the pollutant in the water column” degradation?
12. Why only for such periods (June and July-September)? In other months no runoff? And what about of post-effect of fertilization?
13. Fig. 6. I cannot understand why the high rainfall intensity on 4 h? а – year?
14. Fig. 7. If you have… you could add a photo of plot to scheme.
15. Fig. 9. The units of runoff better to provide in mm. What a coefficient of runoff (the ratio of precipitation to runoff).
16. Fig. 10 and text related to it. Nitrogen and phosphorus discharge in kg? From what area, better kg/ha.
17. Please check the journal rules, probably the References list need to fix.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsComments and Suggestions for Authors:
The manuscript “Simulation study on water quality of rice field ditches considering the effects of rainfall and sediment release” investigated the effects of rainfall return periods and sediment release on the ditch water quality. As a simulation study, my primary concern is the calibration and validation of the model. However, the article's explanation of model calibration and validation is very vague. Thus, it's hard to evaluate the reliability of this article. The author must solve the problem clearly.
Please carefully read the following suggestions to improve the quality of the manuscript:
1. Abstract: This section is poor.
(1) Only phenomena are described. The key data and conclusion are lacking.
(2) Are all the concentrations mentioned total nitrogen or total phosphorus concentrations? Please rephrase to be clearer.
2. Introduction: This section is too rough.
(1) A lot of research progress related to this manuscript is lacking, such as the research on the treatment of pollutants in farmland drainage ditch, the impact factors affecting pollution release, and the simulation of farmland drainage ditch.
(2) There are a large number of unrelated research progress in the abstract, e.g., Lines 72-106 and Lines 117-129.
(3) The effects of different rainfall return periods and ditch sediment release on water quality in paddy field drainage may be limited. However, there's a lot of research on the water quality in paddy field drainage. The author should analyze the research progress in this field.
3. Materials and Methods and Model building and validation: The two parts should be merged and reorganized
(1) The main purpose of this section is to explain how the model is calibrated and validated. The statistical verification parameters were only relative errors, and it was not enough for this model. Other statistical verification parameters should be provided, e.g., NSE, PBIAS, bootstrapping coefficient, and concordance correlation coefficient.
(2) The fitting curve in Figure 3 is an important empirical formula in the model, however, why is it a polynomial relationship? It's hard to be convinced without reason or literature.
(3) All parameters required for the model should be sourced.
4. Results and discussion
The mechanistic discussion seems ambiguous. Most content is a description of the model results. Mechanism analysis should be further discussed and analyzed.
Comments on the Quality of English LanguageExtensive editing of English language required
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsDear author, please see the comments in the attached file.
Comments for author File: Comments.pdf
Author Response
Thank you very much indeed for your comments. We have adopted your suggestions and made changes. This change is in lines 383,400, 401, and 402 of the revised version. Thanks again for your advice.
Reviewer 3 Report
Comments and Suggestions for AuthorsI think the manuscript has been improved.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
Thank you very much indeed for your comments. We have recorrected and edited the manuscript for the English language. Thanks again for your advice.
