Optimizing Non-Point Source Pollution Management: Evaluating Cost-Effective Strategies in a Small Watershed within the Three Gorges Reservoir Area, China
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is generally well-organized and clearly written. The results have practical meaning to understand local pollution current status and the future BMPs application strategies. Below are some comments needed to be addressed before publication.
1. How the land use type is related to the crops should be described, terrace field is cultivated with rice or wheat or corn, and how about the paddy field, is it single rice or rice-wheat rotation? Etc.
2. Fig. 2. The simulation of TN and TP seem to underestimate in March and the low-flow months (8-12). Can you explain why? Estimation under specific periods may indicate underestimation of specific sources, such as the point like sources such as residential sources, which may influence the other results. I expect more discussion on this.
3. Table 4. The results show paddy fields have the highest TP loss rate, and even particulate phosphorus rate, can you explain why? Usually, orchards and sloping fields usually have higher soil loss potential than paddy fields. Paddy fields are usually on relatively flat terrains and its ponding water cultivation makes only extra water exceeding a specific ponding depth can be discharged. So usually the particulate phosphorus loss from paddy field should be not high. Do you use the paddy field modules in SWAT to represent the special ponding water cultivation characteristics？
Author Response
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Reviewer 2 Report
Comments and Suggestions for AuthorsDear authors, thank you for your valuable effort for writing this manuscript. It is very interesting and will add valuable information related to the loads of N and P at the outlet of the basin. Although, it is very important clarify some paragraphs.
My comments:
The paper is well-written and provides essential information for decision-makers, specifically in the area of influence of the watershed. However, although the methodology used is not relevant, it can be applied in other places, considering the factors that influence the movement of N and P elements to the watershed outlet. In addition, it is vital to consider the available information on these elements since their measurement is minimal, and the lack of measured data could seriously influence the results.
Another important aspect is the calibration and validation of the SWAT model, which requires daily information to perform the simulation. In this study, only 11 years were used to simulate monthly (so, did they simulate with daily data and analyze monthly, or did they only simulate monthly?). Taking into consideration the phases of the hydrological cycle, at the moment of rainfall, the first factor before surface runoff that intervenes in the hydrological cycle process is the vegetation cover, which should be the first element to be calibrated (biomass) since it operates as a rain attenuator and depending on the percentage of vegetation cover, the proportion that will runoff will depend on the percentage of vegetation cover. Therefore, the steps to calibrate the SWAT model, in general, should be biomass, surface runoff, sediments, and finally N and P.
In Figure 2, only one year of N and P calibration is shown due to a lack of data, according to the authors. Then, how could one rely on the information of the following years, i.e., the behavior of the N and P elements in the years before and after 2015 is not known? Their behavior could be assumed based on the information obtained from the SWAT model since it was calibrated and validated, but is this information reliable? How can this information be made reliable, considering that the behavior of N and P does not have a linear relationship in time and space? It is suggested to the authors to clarify this part.
Although the methodology describes the use of the entropy weight method, it is unclear where and how it is applied; only the results are shown. It would be essential to clarify how the weights of the factors, scenarios, or combinations were obtained.
The description of Tables 5 and 6 is not clear; it is suggested that the authors revise what was written and try to rewrite these paragraphs to better understand the tables. Thank you.
I should mention that not all the doubts, suggestions, and/or comments described here are not necessary for the authors to clarify in the manuscript. It is left to their consideration whether or not to integrate them, but I suggest that they add what they consider will improve the reading comprehension of the manuscript.
kind regards
Comments for author File: 
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Minor editing of English languaje required
Author Response
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