Soil Erosion Characteristics in Tropical Island Watersheds Based on CSLE Model: Discussion of Driving Mechanisms

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Some parts of the manuscript are not sufficiently detailed, and others are excessively cumbersome, requiring further optimization.

Specific recommendations are as follows:

Introduction:

1. Lines 79-82, it is suggested to move "on the other hand" to the beginning of the sentence to highlight the comparison between USLE, RUSLE, and CSLE models.

2. Check the correctness of the writing of Pearson correlation analysis in lines 123-124.

Results:

3. Lines 292-301, the use of "CC" to indicate correlation coefficient values needs explanation. It seems you are referring to Pearson correlation, but there is no explanation of "CC" in the results or lines 167-169 of the methodology. It is recommended to add an explanation in the methodology section.

4. In Section 4.3 (Lines 292-301), it is suggested to present the data from Table 2 and Table 3 quantitatively in the text description.

5. In Section 4.4 (Lines 323-324), where the results of spatial attribution analysis of soil erosion are discussed with different scenarios, it is recommended to modify the sentence "Soil erosion is driven by a combination of natural and anthropogenic factors, both when there is a decreasing change and when there is an increasing change (Figure 6)" by adding a reference to Table 1 to indicate the corresponding scenarios.

Discussion:

6. Lines 346-356, it is suggested to add references to support further discussion. For example, "Understanding the relationship between drivers and changes in soil erosion can help us better assess soil erosion dynamics." Adding references to relevant studies can support this statement.

7. In Section 5.1, the first paragraph provides a detailed explanation of the soil erosion driving factors in different climatic zones. To make a comparison with the soil erosion situation in the three major watersheds of Hainan Island, it is recommended to provide a more detailed analysis of the influence of human factors on soil erosion in these watersheds.

8. Lines 412-416, it is recommended to provide references to support the statement "In the context of considering the influence of natural conditions such as climate and topography, people use water resources from some rivers and reservoirs for hydraulic engineering measures such as flood control and storage, inter-basin water transfer, and hydropower generation," which leads to a decrease in soil erosion.

9. In Section 5.3, "Causes and countermeasures of watersheds with dense spatial distribution," there is excessive content. It is recommended to streamline the analysis of causes and measures.

Author Response

Reply to the comments

 

Dear Editor and Reviewers:

We thank the referees for their positive evaluation of our manuscript and for their insightful comments, which have been a great help in improving the quality of our paper. We carefully revised the paper according to these comments and suggestions. The related parts of the paper have been rewritten and improved. For your easy reading and evaluation, the changed parts are marked using RED COLORED text in the revised version. Please note that the line numbers mentioned in reviewers’ comments refer to the original version, while in our reply refer to the revised version.

 

We hope the revised version is satisfactory for publication, and of course, we are more than happy to improve the paper again according to further comments and suggestions they might come.

 

Reply to the comments from Reviewer #1

Some parts of the manuscript are not sufficiently detailed, and others are excessively cumbersome, requiring further optimization.

Detailed comments:

Introduction:

1. Lines 79-82, it is suggested to move "on the other hand" to the beginning of the sentence to highlight the comparison between USLE, RUSLE, and CSLE models.

Reply: Thank you for your kind suggestion. We have made modifications to the sentence as per your suggestion, please refer to lines 72-75 for details.

 

2. Check the correctness of the writing of Pearson correlation analysis in lines 123-124.

Reply: Thank you for your reminder. We have reviewed the entire manuscript and made corrections to the presentation of the Pearson correlation analysis.

 

Results:

3. Lines 292-301, the use of "CC" to indicate correlation coefficient values needs explanation. It seems you are referring to Pearson correlation, but there is no explanation of "CC" in the results or lines 167-169 of the methodology. It is recommended to add an explanation in the methodology section.

Reply: Thank you for your reminder. We have added explanations about "CC" in the Method. Please refer to lines 212-213 for details.

 

4. In Section 4.3 (Lines 292-301), it is suggested to present the data from Table 2 and Table 3 quantitatively in the text description.

Reply: Thank you for your kind suggestion. We have appropriately included the data from Table 2 and Table 3 in Section 4.3. Please refer to lines 398-405 for details.

 

5. In Section 4.4 (Lines 323-324), where the results of spatial attribution analysis of soil erosion are discussed with different scenarios, it is recommended to modify the sentence "Soil erosion is driven by a combination of natural and anthropogenic factors, both when there is a decreasing change and when there is an increasing change (Figure 6)" by adding a reference to Table 1 to indicate the corresponding scenarios.

Reply: Thank you for your kind suggestion. We have made modifications to the paragraph. Specifically, it now reads as follows: "The scenarios driven by a combination of natural and anthropogenic factors have the most pronounced impact on the variation of soil erosion (Figure 6)." Please refer to lines 412-413 for the details.

 

Discussion:

6. Lines 346-356, it is suggested to add references to support further discussion. For example, "Understanding the relationship between drivers and changes in soil erosion can help us better assess soil erosion dynamics." Adding references to relevant studies can support this statement.

Reply: Thank you for your kind suggestion. We have added a reference to the sentence. Please refer to the manuscript's reference [54] for further details.

Reference:

54. Guo, X.; Shao, Q. Spatial pattern of soil erosion drivers and the contribution rate of human activities on the Loess Plateau from 2000 to 2015: A boundary line from northeast to southwest. Remote Sens 2019, 11, 2429. https://doi.org/10.3390/rs11202429

 

7. In Section 5.1, the first paragraph provides a detailed explanation of the soil erosion driving factors in different climatic zones. To make a comparison with the soil erosion situation in the three major watersheds of Hainan Island, it is recommended to provide a more detailed analysis of the influence of human factors on soil erosion in these watersheds.

Reply: Thank you for your kind suggestion. In order to provide a detailed analysis of the impact of human factors on watershed water and soil loss, we have outlined various anthropogenic factors (such as land development, urbanization, and agricultural expansion) that can potentially affect soil erosion in tropical watersheds. Additionally, the construction of reservoirs and roads alters water flow paths and land use patterns, thereby increasing the risks of soil erosion and water and soil loss. Please refer to the revised version of the manuscript, lines 466-472, for specific modifications.

 

8. Lines 412-416, it is recommended to provide references to support the statement "In the context of considering the influence of natural conditions such as climate and topography, people use water resources from some rivers and reservoirs for hydraulic engineering measures such as flood control and storage, inter-basin water transfer, and hydropower generation," which leads to a decrease in soil erosion.

Reply: Thank you for your kind suggestion. We have added relevant references, please refer to Reference 58 in the manuscript for details.

Reference:

58. Xin, Z.; Ran, L.; Lu, X. Soil erosion control and sediment load reduction in the Loess Plateau: policy perspectives. Int J Water Resour D 2012, 28, 325-341. https://doi.org/10.1080/07900627.2012.668650

 

9. In Section 5.3, "Causes and countermeasures of watersheds with dense spatial distribution," there is excessive content. It is recommended to streamline the analysis of causes and measures.

Reply: Thank you for your kind suggestion. We have simplified the conclusions. Please see Section 5.3 in the revised version.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer #2 comments:

Manuscript number: land-2867980

Manuscript title: Soil erosion characteristics in tropical island watersheds based on CSLE model: discussion of driving mechanisms

 

Dear Authors, I have now read and assessed your manuscript with the abovementioned details. The topic of the manuscript is interesting. However, more work should be put to improve the overall quality. Please, see my queries/specific comments below.

1.     L15-16 – how can you justify this claim?

2.     The abstract should be revised. It abstract should be able concisely answer the questions about the background of study and novelty/knowledge gap(s), what was done, why it was done, how it was done, the major findings, and the conclusion and/or implication(s) of the findings.

3.     Please, justify the novelty in the introduction.

4.     Literature review in the introduction should be focused.

5.     Figure 1 – improve the legibility of texts.

6.     All equations should be cited in main text.

7.     The results and discussion sections should be robust and also be supported by literature-based data, justifications, and comparisons.

8.     There are many complex sentences that could throw your readers off. Keep the writeup simple. Your readers should be able to follow you in bits.

9.     The conclusions should be concise. This section should be able to summarize the findings and provide conclusive statement(s). Do so in line with the aim and objectives of the study. Justify the novelty and significances of the study more in the conclusions.

10.  The limitations of the study should be highlighted. Also, provide perspectives for future research.

Best wishes.

 

Comments on the Quality of English Language

Needs revision

Author Response

Reply to the comments

 

Dear Editor and Reviewers:

We thank the referees for their positive evaluation of our manuscript and for their insightful comments, which have been a great help in improving the quality of our paper. We carefully revised the paper according to these comments and suggestions. The related parts of the paper have been rewritten and improved. For your easy reading and evaluation, the changed parts are marked using RED COLORED text in the revised version. Please note that the line numbers mentioned in reviewers’ comments refer to the original version, while in our reply refer to the revised version.

 

We hope the revised version is satisfactory for publication, and of course, we are more than happy to improve the paper again according to further comments and suggestions they might come.

 

Reply to the comments from Reviewer #2

Main comment for the full paper:

Dear Authors, I have now read and assessed your manuscript with the abovementioned details. The topic of the manuscript is interesting. However, more work should be put to improve the overall quality. Please, see my queries/specific comments below.

1. L15-16 – how can you justify this claim?

Reply: Thank you for your reminder. We apologize for the oversight in the spelling of "Pearson correlation analysis." We have thoroughly reviewed the entire document and made the necessary corrections.

 

2. The abstract should be revised. It abstract should be able concisely answer the questions about the background of study and novelty/knowledge gap(s), what was done, why it was done, how it was done, the major findings, and the conclusion and/or implication(s) of the findings.

Reply: Thank you for your comments and kind suggestions. We have revised the abstract according to the framework of research background and novelty, what we did, why we did it, how we did it, main findings, and conclusions. Please refer to lines 12-32 of the revised manuscript for the modified version.

 

3. Please, justify the novelty in the introduction.

Reply: Thank you for your kind suggestion. We have added a new paragraph in the revised version of the manuscript to illustrate the novelty of our research. Additionally, in the last paragraph of the introduction, we have provided a supplementary description of the significance of conducting soil erosion research in the study area. Please refer to lines 105-123 and 137-152 for more details.

 

4. Literature review in the introduction should be focused.

Reply: Thank you for your kind suggestion. We have added some necessary literature reviews to the introduction section. Please refer to the content in the third and fifth paragraphs of the introduction for more details.

 

5. Figure 1 – improve the legibility of texts.

Reply: Thank you for your kind suggestion. We have made revisions to Figure 1 to enhance the readability and smoothness of the text.

 

6. All equations should be cited in main text.

Reply: Thank you for your kind suggestion. We have supplemented the method description and formulas for transition matrix method and the Chinese Soil Loss Equation model in the main text. Please refer to lines 256-269 and 295-309 for detailed information.

 

7. The results and discussion sections should be robust and also be supported by literature-based data, justifications, and comparisons.

Reply: Thank you for your kind suggestion. We have added more relevant references to the conclusion and discussion sections to support the reliability of the study. Please refer to the results and discussion sections for more details. The added references are listed as follows.

References:

54. Guo, X.; Shao, Q. Spatial pattern of soil erosion drivers and the contribution rate of human activities on the Loess Plateau from 2000 to 2015: A boundary line from northeast to southwest. Remote Sens 2019, 11, 2429. https://doi.org/10.3390/rs11202429
55. Leh, M.; Bajwa, S.; Chaubey, I. Impact of land use change on erosion risk: an integrated remote sensing, geographic infor-mation system and modeling methodology. Land Degrad Dev 2013, 24, 409-421. https://doi.org/10.1002/ldr.1137
56. Xin, Z.; Ran, L.; Lu, X. Soil erosion control and sediment load reduction in the Loess Plateau: policy perspectives. Int J Water Resour D 2012, 28, 325-341. https://doi.org/10.1080/07900627.2012.668650

 

8. There are many complex sentences that could throw your readers off. Keep the writeup simple. Your readers should be able to follow you in bits.

Reply: Thank you for your kind suggestion. We have simplified and rephrased complex sentences in the manuscript, such as streamlining the discussion section in Section 5.3 and rewriting portions of Lines 466-472.

 

9. The conclusions should be concise. This section should be able to summarize the findings and provide conclusive statement(s). Do so in line with the aim and objectives of the study. Justify the novelty and significances of the study more in the conclusions.

Reply: Thank you for your kind suggestion. We have streamlined the content of the summary section, highlighting the novelty and significance of the study. We then summarize the findings of the investigation and provide conclusive statements. Please refer to lines 598-618 for a detailed overview.

 

10. The limitations of the study should be highlighted. Also, provide perspectives for future research.

Reply: Thank you for your kind suggestion. We have incorporated a description of the limitations of the study and prospects for future research into the conclusion section. Specifically, we have added the following statement: "This study identifies that climate-human activity scenarios jointly contribute to the largest proportion of the observed increase in soil water erosion. However, the study primarily describes human activities through changes in land use. Therefore, it is crucial to conduct research on the impact and contribution of extreme climate events, major engineering projects, and other factors to soil water erosion. Such studies are of significant importance for identifying the driving forces behind soil water erosion." Please refer to lines 619-624 for further details.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

land-2867980 titled "Soil erosion characteristics in tropical island watersheds based on CSLE model: discussion of driving mechanisms”

 

My comments on the manuscript are as follow:

 

1.     I have gone through the manuscript thoroughly, the paper is important and may of interest to a wider community. The authors have used used CSLE model to predict the present and future potential Soil erosion characteristics in three major watersheds of Hainan island.

 

2.     Abstract section: This is not clear at all, and will not communicate a clear message to reader at present and needs substantial re-phrasing for clarity and flow of the text along information/meaning. There are ambiguous statements and the details in results sections are not exactly the same. For example see:

 

L17-27: “…..The scenario involving both natural and anthropogenic factors had the largest impact on soil erosion changes, with co-driven increase affecting 53.56% of the area ……………. Anthropogenic factors (IH=77.73%) drove increased soil erosion in the Nandu River basin, while a combination of climate and anthropogenic factors (DB=69.24%) influenced decreased changes…….” Where the later statement is contradictory to the statement above it (both needs to be in synchrony).

 

Similarly, in L22-23: “………….Climate and human activities contributed to soil erosion increase (IB=22.40%) in the Changhua River basin, while human activities mainly caused the decrease  (DH=27.58%)” for readers it is put forwarded as/like if the effects of both (Climate and human activities) in conjunction (i.e. A+B or 22.40%) is less than that of individual (A or B alone, i.e. the human activities mainly caused the decrease  DH=27.58%). This do not communicate the exact message needed.

L24: “….. Climate increased soil erosion (IC=34.99%), while human activities decreased it  (DH=36.16%) in the Wanquan River basin………”

Some more elaboration of the “Climate” is needed, furthermore neither the data provided above (in abstract section) nor in subsequent sections is supportive of the claims. In conclusion for instance: “….The study showed that both human activities and natural factors drove soil erosion in tropical regions, with greater impact from human activities….”

Phrases like these would need stringent rephrasing for clarity of meaning and flow of uniform and consistent information.

 

3.     Keywords: the rest are OK but “drive mechanism” may not be that much helpful for keywords

 

4.     Introduction: The MS is based on/dealing with Soil erosion characteristics in tropical island/s. However, there are no details in introduction section how erosion will be defined at first in such islands? It is such a broad area/term and limitations of the model used is not documented explicitly as it is mentioned for RUSLE for instance. Needless, to mention but it is a model after all (based on predictions). Also, how cropping pattern altered the overall structure and layering patterns in results or had it any potential to alter? It I could not locate these information in introduction section and that needs to be mentioned/elaborated to help readers and future endeavors in the same field.

 

5.     I would specifically like to learn on how is this modelling approach (predicted here) is fitting into a real world scenarios particularly for identification of soil erosion hotspots in the area. As the same areas/allied regions have been studied earlier or at least information is available using other approaches. Such information will be very handy and may be provided in any relevant section.

 

6.     Also the rationale, why from 1991 to 2020 time frame specifically is chosen? I understand there would be a reason of course for that, but at the moment it is not clear form the provided text. Such information would be very handy and particularly if there are any/some recorded extreme events that could be mapped by the model used here to the relevant. This would further authenticate the results and application of the model more widely (outside China) .  

 

7.     It is commendable that the objectives are laid down explicitly in the introduction section. However, this MUST be overseen with great care, that results given in Results section and summarized in the abstract section are not coherent to objectives laid out here.

 

8.     Lines 128-129: “…The study is of great theoretical and practical importance for improving land productivity in red soil hilly areas, effectively controlling soil erosion and maintaining ecological security in similar areas……” similar lines may be added at the end of conclusion section or may be added as a wary forward how this study is helpful to drive/complement other studies.

 

9.     Materials and Methods: This section is OK and has appropriate details and could be reproduced by everyone with similar expertise. However, I will encourage the authors to re-visit the whole text for clarity of the text and meaning to be consistently used. Further, the references/citation may overlooked again so that exact primary references/sources are cited.

 

10.  Results and Discussion:

 

11.  L320-321: “…..The land use transfer matrix was used to identify land use changes for the 31 years between 1990 and 2020……” Is that correct? Or it is form 1991 for 30 years as described elsewhere in the MS.

 

12.  Figures for example Figure 6, is hot highlighting the different scenarios clearly. Also for all keys used there MUST be some sort of information so that the Figures and their legends are self-explanatory. Tables may also be treated likewise.  

 

13.  I also could not see the ethical approval of the study, who/which body approved this study if the data contain collection from restricted/reserved parks or areas.

 

 

14.  All abbreviations needs to be described in full at their first place of mention in the MS and then the abbreviated forms could be used.

 

15.  Conclusions:

Objectives for the study were laid out as:

(1) to analyze the annual average variation of each hydrothermal factor (rainfall, temperature, reference crop potential evapotranspiration) and aridity index using GIS technology and slope trend analysis methods, as well as the spatial variation trends multi-year.

(2) to analyze the spatial correlation between soil erosion and aridity index, and to explore the effect of land use shift changes on soil erosion using the land use shift matrix.

(3) to identify, through spatial attribution analysis, the dominant drivers influencing soil erosion change - natural, anthropogenic or combined natural-anthropogenic drivers.

 

However, the conclusions are not really complementing the objectives. There must be coherence of the objectives and conclusions and described loudly along the novelty. It is understandable that the conclusions provided here in this sections are important to mention, but they must be judiciously linked to the specific objectives. So that the flow of information from title to the conclusion are all handy and supporting /conceiving  the same rationale/problem studied.

 

In general the English language is good and conveys what it meant to do. However, it is desirable that English language may be critically reviewed once more, there are few typos and grammar related minor issues within the MS. Similarly, all intext references may be double checked with the list at the end and vice versa for availability.

 

 

Decision:

While the study is within the scope of the journal, and information may be handy and of wider interest and the MS may be accepted for publication after inclusion of the aforementioned suggestions”.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

see the report attached or as copied above. 

Author Response

Reply to the comments

 

Dear Editor and Reviewers:

We thank the referees for their positive evaluation of our manuscript and for their insightful comments, which have been a great help in improving the quality of our paper. We carefully revised the paper according to these comments and suggestions. The related parts of the paper have been rewritten and improved. For your easy reading and evaluation, the changed parts are marked using RED COLORED text in the revised version. Please note that the line numbers mentioned in reviewers’ comments refer to the original version, while in our reply refer to the revised version.

 

We hope the revised version is satisfactory for publication, and of course, we are more than happy to improve the paper again according to further comments and suggestions they might come.

 

Reply to the comments from Reviewer #3

1. I have gone through the manuscript thoroughly the paper is important and may of interest to a wider community. The authors have used CSLE model to predict the present and future potential Soil erosion characteristics in three major watersheds of Hainan Island.

Main comment for the full paper:

2. Abstract section: This is not clear at all, and will not communicate a clear message to reader at present and needs substantial re-phrasing for clarity and flow of the text along information/meaning. There are ambiguous statements and the details in results sections are not exactly the same.

For example see: L17-27: “…..The scenario involving both natural and anthropogenic factors had the largest impact on soil erosion changes, with co-driven increase affecting 53.56% of the area ……………. Anthropogenic factors (IH=77.73%) drove increased soil erosion in the Nandu River basin, while a combination of climate and anthropogenic factors (DB=69.24%) influenced decreased changes…….” Where the later statement is contradictory to the statement above it (both needs to be in synchrony).

Similarly, in L22-23: “…………Climate and human activities contributed to soil erosion increase (IB=22.40%) in the Changhua River basin, while human activities mainly caused the decrease (DH=27.58%)” for readers it is put forwarded as/like if the effects of both (Climate and human activities) in conjunction (i.e. A+B or 22.40%) is less than that of individual (A or B alone, i.e. the human activities mainly caused the decrease DH=27.58%). This do not communicate the exact message needed.

L24: “…. Climate increased soil erosion (IC=34.99%), while human activities decreased it (DH=36.16%) in the Wanquan River basin………” Some more elaboration of the “Climate” is needed, furthermore neither the data provided above (in abstract section) nor in subsequent sections is supportive of the claims. In conclusion for instance: “…The study showed that both human activities and natural factors drove soil erosion in tropical regions, with greater impact from human activities….” Phrases like these would need stringent rephrasing for clarity of meaning and flow of uniform and consistent information.

Reply: Thank you for your kind suggestion. We apologize for the lack of clarity in that section. To clarify, the main logic of the section is as follows: "…The scenario involving both natural and anthropogenic factors had the largest impact on soil erosion changes, with co-driven increase affecting 53.56% of the area…" represents the identification results for the primary driving factors in the entire study area, followed by the identification results for distinguishing the primary driving factors in three different watersheds.  In the description of the proportions of driving increases and driving decreases in the three different watersheds, the combined influence of climate and human activities is not calculated as A+B. Detailed proportion information can be found in Table 4, while the scenario differentiations are shown in Table 1.

We differentiate the section by modifying "…The scenario involving both natural and anthropogenic factors had the largest impact on soil erosion changes, with co-driven increase affecting 53.56% of the area…" to " The research results indicate that scenarios driven by the combined of natural and human fac-tors have the greatest impact on soil erosion changes in the entire study area. Co-driven in-creases affected 53.56% of the area, while co-driven decreases affected 21.74%." In order to distinguish the research results for identifying the primary driving factors in the entire study area and the research results for distinguishing the primary driving factors in three different watersheds. Please see lines 22-30 for details.

 

3. Keywords: the rest are OK but “drive mechanism” may not be that much helpful for keywords

Reply: We appreciate your suggestion, and we have removed "drive mechanism" from the keywords.

 

4. Introduction: The MS is based on/dealing with Soil erosion characteristics in tropical island/s. However, there are no details in introduction section how erosion will be defined at first in such islands? It is such a broad area/term and limitations of the model used is not documented explicitly as it is mentioned for RUSLE for instance. Needless, to mention but it is a model after all (based on predictions). Also, how cropping pattern altered the overall structure and layering patterns in results or had it any potential to alter? It I could not locate these information in introduction section and that needs to be mentioned/elaborated to help readers and future endeavors in the same field.

Reply: Thank you for your kind suggestion. For a detailed definition of soil erosion on tropical islands, we have added the following statement: " The proposal of ecological conservation and the development strategy of building Hai-nan Province into an international tourist island have raised new and higher requirements for soil and water conservation. In order to promote soil erosion prevention and control, as well as the protection and rational utilization of soil and water resources, dynamic monitoring of soil erosion has been conducted in various regions of Hainan Province. According to the 2017 National Government Work Report, the entire island of Hainan has been designated as a prone area for soil and water loss." To elucidate the background, progress, and current state of soil erosion research on Hainan Island.

We have supplemented the advantages and limitations of the CSLE model. The advantages include considering a wide range of slope steepness and slope length, as well as taking into account the impact of vegetation cover on soil erosion. However, the limitations lie in the need to adjust and calibrate parameters based on specific regions and vegetation types. Please find the specific explanations added to lines 72-75 and 76-80 of the introduction.

 

5. I would specifically like to learn on how is this modelling approach (predicted here) is fitting into a real world scenarios particularly for identification of soil erosion hotspots in the area. As the same areas/allied regions have been studied earlier or at least information is available using other approaches. Such information will be very handy and may be provided in any relevant section.

Reply: Thank you for your kind suggestion. The CSLE model is based on physical processes and empirical formulas to assess the erosion intensity in different regions by calculating the soil erosion modulus within a watershed. When applying the CSLE model, the first step is to collect and process relevant input data, including terrain data (such as elevation, slope, and aspect), rainfall data, soil characteristic data, and vegetation data. These data are used for parameter setting and terrain analysis in the model.

The modeling approach of the CSLE model takes into account factors such as slope, slope length range, and vegetation cover's influence on soil erosion. By incorporating these factors into the model, it is possible to calculate the soil erosion amount in different areas within the watershed and generate spatial distribution maps of soil erosion intensity. By analyzing these results, it is possible to identify hotspots of soil erosion, which are areas with higher erosion intensity.

However, to improve the model's adaptability and accuracy, parameter adjustment and calibration are necessary based on the specific characteristics of the region. This means that in practical applications, the model's parameters need to be appropriately adjusted considering the specific conditions and measured data of the region to better align with the soil erosion situation in that area.

This aspect can be elucidated through an explanation of the advantages and limitations of CSLE. Please see lines 72-75 and 76-80 for details.

 

6. Also the rationale, why from 1991 to 2020 time frame specifically is chosen? I understand there would be a reason of course for that, but at the moment it is not clear form the provided text. Such information would be very handy and particularly if there are any/some recorded extreme events that could be mapped by the model used here to the relevant. This would further authenticate the results and application of the model more widely (outside China).

Reply: The decision to specifically examine the time span from 1991 to 2021 for studying soil erosion in the three major basins of tropical Hainan Island holds significance due to its inclusion of key events and policy measures. This period encompasses the years before and after the implementation of China's Grain for Green Program in 1999, as well as the pivotal announcement in 2010 declaring Hainan Island build an international tourist island. Additionally, the study concludes in 2021, coinciding with the official launch of the Hainan Free Trade Port in 2020.

Furthermore, the research period witnessed notable extreme events in the study area. The Changhua River Basin faced significant impacts from "Super Typhoon Rammasun" in 2014 and "Severe tropical storm Dianmu" in 2016. In 2014, the highest total precipitation occurred in Changjiang Li Autonomous County, while in 2016, the area of Bawangling in Changjiang Li Autonomous County experienced the highest recorded rainfall, reaching nearly 1000 mm.

Considering the changes in land use, human factors, and natural factors during the implementation of these key events and policy measures is crucial for comprehending the study area's soil erosion dynamics.

 

7. It is commendable that the objectives are laid down explicitly in the introduction section. However, this MUST be overseen with great care, that results given in Results section and summarized in the abstract section are not coherent to objectives laid out here.

Reply: Thank you for your kind suggestion. We have made revisions to the abstract and conclusion sections, with the conclusion section now used to summarize the research findings in relation to the stated objectives. The abstract primarily presents an overview of the main task of the entire paper, which is the spatial attribution analysis of soil erosion. Please refer to the revised version, lines 12-32 and 598-624, for more details.

 

8. Lines 128-129: “…The study is of great theoretical and practical importance for improving land productivity in red soil hilly areas, effectively controlling soil erosion and maintaining ecological security in similar areas……” similar lines may be added at the end of conclusion section or may be added as a wary forward how this study is helpful to drive/complement other studies.

Reply: Thank you for your kind suggestion. We have taken your suggestion into account and placed the mentioned content at the end of the first paragraph in the conclusion section. Please refer to lines 615-618 for more details.

 

9. Materials and Methods: This section is OK and has appropriate details and could be reproduced by everyone with similar expertise. However, I will encourage the authors to re-visit the whole text for clarity of the text and meaning to be consistently used. Further, the references/citation may overlooked again so that exact primary references/sources are cited.

Reply: Thank you for your kind suggestion. We have reviewed the text content in the Methods section to ensure clarity and consistent usage of terms. We have also added the appropriate primary references. Please refer to the Methods section and the following references for more details.

References:

50. Liu, B.; Pan, L.; Qi, Y.; Guan, X.; Li, J. Land use and land cover change in the Yellow River Basin from 1980 to 2015 and its impact on the ecosystem services. Land 2021, 10, 1080. https://doi.org/10.3390/land10101080
51. Zhang, H.; Zhang, R.; Qi, F.; Liu, X.; Niu, Y.; Fan, Z.; Zhang, Q.; Li, J.; Yuan, L.; Song, Y.; Yang, S.; Yao, X. The CSLE mod-el based soil erosion prediction: Comparisons of sampling density and extrapolation method at the county level. Catena 2018, 165, 465-472. https://doi.org/10.1016/j.catena.2018.02.007

 

10. Results and Discussion:
11. L320-321: “…The land use transfer matrix was used to identify land use changes for the 31 years between 1990 and 2020……” Is that correct? Or it is form 1991 for 30 years as described elsewhere in the MS.

Reply: Thank you for your kind suggestion. We apologize for not providing an explanation in this section. Due to data availability, the land use data we used was sourced from the Resource and Environmental Science Data Center of the Chinese Academy of Sciences (http://www.resdc.cn/). This dataset includes land use data for the years 1990 and 2020. Therefore, we used it as an approximation year for the years 1991 and 2021 to conduct the analysis of land use transfer matrices. The data source information has been added to the Methods section, in lines 193-195.

 

12. Figures for example Figure 6, is hot highlighting the different scenarios clearly. Also for all keys used there MUST be some sort of information so that the Figures and their legends are self-explanatory. Tables may also be treated likewise.

Reply: Thank you for your kind suggestion. We have added explanations for the scenarios corresponding to the different abbreviations in the legend of Figure 6.

 

13. I also could not see the ethical approval of the study, who/which body approved this study if the data contain collection from restricted/reserved parks or areas.

Reply: Our research does not involve human subjects, human materials, human tissues, human data, or animal research. It also does not include any confidential data. The ethical approval has been placed after the conclusion. Additionally, we have provided information on the data source in the Method section, in lines 187-196.

 

14. All abbreviations needs to be described in full at their first place of mention in the MS and then the abbreviated forms could be used.

Reply: Thank you for your reminder. We have reviewed the content that includes the section with abbreviations and made the necessary modifications.

 

15. Conclusions:

Objectives for the study were laid out as:

(1) to analyze the annual average variation of each hydrothermal factor (rainfall, temperature, reference crop potential evapotranspiration) and aridity index using GIS technology and slope trend analysis methods, as well as the spatial variation trends multi-year.

(2) to analyze the spatial correlation between soil erosion and aridity index, and to explore the effect of land use shift changes on soil erosion using the land use shift matrix.

(3) to identify, through spatial attribution analysis, the dominant drivers influencing soil erosion change - natural, anthropogenic or combined natural-anthropogenic drivers. However, the conclusions are not really complementing the objectives. There must be coherence of the objectives and conclusions and described loudly along the novelty. It is understandable that the conclusions provided here in this sections are important to mention, but they must be judiciously linked to the specific objectives. So that the flow of information from title to the conclusion are all handy and supporting /conceiving the same rationale/problem studied.

In general the English language is good and conveys what it meant to do. However, it is desirable that English language may be critically reviewed once more, there are few typos and grammar related minor issues within the MS. Similarly, all intext references may be double checked with the list at the end and vice versa for availability.

Reply: Thank you for your kind suggestion. Based on your suggestions, we have revised the conclusion section. Firstly, we summarized the research findings corresponding to the objectives. Secondly, we highlighted the novelty and significance of the study. Lastly, we addressed the limitations of the research and provided future prospects. Please refer to lines 598-624 for further details.

 

Decision:

While the study is within the scope of the journal, and information may be handy and of wider interest and the MS may be accepted for publication after inclusion of the aforementioned suggestions”.

 

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

In this study, authors used various soil erosion models, including slope trend analysis, Person correlation analysis, land use transfer matrix, and spatial attribution analysis, in three watersheds of Hainan Island, China. The study found that both climate and human activities significantly contribute to soil erosion in the study area. The study highlights the challenges that land managers face in addressing soil erosion and its contributing factors. The paper is well written and worth publishing. However, there are a few queries that need to be addressed before it can be accepted.

 1. Figure 1 should be included in the “Methodology” section with legible text and high resolution.

2. How does the study address any limitations or uncertainties in the data or model used?
3. Add the significance of the current study in the introduction section.

4. A paragraph about recent literature should also be added in the introduction section.

5. The last paragraph of the “Introduction” section should discuss other scientific studies about soil erosion models done in the study area in the past (If any). Further, the usefulness of this study from the viewpoints of national/regional and international research communities should also be mentioned.

6. Provide more details about the statistical parameters used to assess the model's performance.

 

7. Recheck the references and correct them where required according to the journal format.

 

I appreciate your scientific effort to produce this manuscript. I recommended this manuscript for publication with minor corrections. 

Comments on the Quality of English Language

The quality of the English language is good.

Author Response

Reply to the comments

 

Dear Editor and Reviewers:

We thank the referees for their positive evaluation of our manuscript and for their insightful comments, which have been a great help in improving the quality of our paper. We carefully revised the paper according to these comments and suggestions. The related parts of the paper have been rewritten and improved. For your easy reading and evaluation, the changed parts are marked using RED COLORED text in the revised version. Please note that the line numbers mentioned in reviewers’ comments refer to the original version, while in our reply refer to the revised version.

 

We hope the revised version is satisfactory for publication, and of course, we are more than happy to improve the paper again according to further comments and suggestions they might come.

 

Reply to the comments from Reviewer #4

Main comment for the full paper:

In this study, authors used various soil erosion models, including slope trend analysis, Person correlation analysis, land use transfer matrix, and spatial attribution analysis, in three watersheds of Hainan Island, China. The study found that both climate and human activities significantly contribute to soil erosion in the study area. The study highlights the challenges that land managers face in addressing soil erosion and its contributing factors. The paper is well written and worth publishing. However, there are a few queries that need to be addressed before it can be accepted.

I appreciate your scientific effort to produce this manuscript. I recommended this manuscript for publication with minor corrections.

Reply: Thank you for your positive evaluation in general and professional comments and suggestions, which have been taken full consideration in the revised version. And below are our point-by-point replies to your specific comments and suggestions.  

Detailed comments:

1. Figure 1 should be included in the “Methodology” section with legible text and high resolution.

Reply: Thank you for your kind suggestion. We have made revisions to Figure 1 by placing it below the first paragraph of the Methods section. Additionally, we have modified the text to ensure its smoothness, clarity, and increased resolution.

 

2. How does the study address any limitations or uncertainties in the data or model used?

Reply: The meteorological data, MOD13Q1 data, land use data, and soil data used in this study were obtained from reliable sources. Specifically, they were sourced from the National Meteorological Information Center-China Meteorological Data Service Center (http:data.cma.cn), the Goddard Space Flight Center of NASA (https://ladsweb.modaps.eosdis.nasa.gov/search), the Resource and Environment Science Data Center of the Chinese Academy of Sciences (http://www.resdc.cn/), and the Harmonized World Soil Database (http://westdc.westgis.ac.cn), respectively. A detailed introduction and formula for the Chinese soil erosion equation model are provided in the method section. To address the uncertainties and limitations of the model, a combination of remote sensing technology and field surveys was employed in this study. The specific algorithms used for each factor in the model adhere to the standards outlined in the Technical Guidelines for Soil Erosion Monitoring in 2020 and the Classification and Grading Standards for Soil Erosion (SL190-2007).

 

3. Add the significance of the current study in the introduction section.

Reply: Thank you for your reminder. We have added the research significance to the end of the introduction, please refer to lines 148-152 for more details.

 

4. A paragraph about recent literature should also be added in the introduction section.

Reply: Thank you for your kind suggestion. We have added a new paragraph to the revised version of the manuscript, in lines 105-123, describing the current research on the influencing factors of soil erosion.

 

5. The last paragraph of the “Introduction” section should discuss other scientific studies about soil erosion models done in the study area in the past (If any). Further, the usefulness of this study from the viewpoints of national/regional and international research communities should also be mentioned.

Reply: Thank you for your kind suggestion. We have revised the last paragraph of the introduction to discuss the previous research conducted on soil erosion in Hainan Island. We have also highlighted the usefulness of this study from the perspectives of national and local policies and the research conducted. Please refer to lines 137-152 in the introduction for more details.

 

6. Provide more details about the statistical parameters used to assess the model's performance.

Reply: We conducted a comparative analysis between the soil erosion dynamic monitoring results completed by the Ministry of Water Resources of the People's Republic of China in 2020 and the soil erosion monitoring results in the three major river basins of Hainan Island in our study in 2021 to verify the reliability of the model simulation results. Based on a study area of 14,614 km², we used the random point creation tool in the GIS platform to create 14,614 random validation points in the study area for comparing and validating the validation points with the 2020 soil erosion dynamic monitoring data results from the Ministry of Water Resources and the 2021 research estimation results. Among the validation points distributed in different erosion intensity levels, a total of 13,381 points showed consistent erosion intensity levels between the 2020 Ministry of Water Resources data results and the 2021 research estimation results, accounting for 91.56% of the total validation points. Among the different erosion levels, the simulated values of slight erosion had the highest number of validation points within the range of the 2020 monitoring results, with 4,226 points and an accuracy rate of 92.66%. The next highest was the moderate level, with 3,230 validation points within the range of the 2020 monitoring results and an accuracy rate of 87.82%. In the other erosion levels, the number of validation points was relatively small, but the accuracy rates were all above 90%. In conclusion, the research monitoring results have a high overall accuracy and reliability.

 

7. Recheck the references and correct them where required according to the journal format.

Reply: Thank you for your reminder. We have rechecked the references and made necessary modifications to adhere to the journal's formatting requirements.

 

Author Response File: Author Response.docx

Reviewer 5 Report

Comments and Suggestions for Authors

The article “Soil erosion characteristics in tropical island watersheds based on CSLE model: discussion of driving mechanisms”, evaluates the consequences of soil erosion of Hainan Island in China.

The article an be published but in my opinion needs some corrections in the way of presentation. Additionally, the are a few mistakes in English.

Abstract

The abstract should be expanded and introduce the reader to the philosophy and the findings of the article.

Also, some parts must be rephrased. Particularly, at lines 14,17 and 25, the symbol “:” should be removed. The authors are advised to provide a text with flow.

1.      Introduction

The introduction is clear and to the topic.

However, lines 115 – 130 would be better to be removed from introduction and presented at the methodology.

2.      Study area

The authors can add some extra information concerning the population or some general information about the climate and the anthropogenic factors that occur.

3.      Methodology

Please provide a paragraph referring to the data origin and sources

Also, the symbol “*” in the equations does not mean anything. Please replace it with “×” or “·”

4.      Result analysis

Line 313: please number the figure

4.4  Analysis of the influence of human activities on soil water erosion

I have the opinion the theoretical background of the transfer matrix (table 2) should be presented in methods.

Also, the authors should also explain in methods how the table 3 occurred

 The paragraphs 5 and 6 are based to the findings of the survey, personally I have no comments or changes for them.

Comments on the Quality of English Language

Concerning to the English style I have the following comments

Lines 31-32: “Soil erosion research provides an essential medium for humans to use the earth's resources appropriately and preserve and restore environmental conditions.”

Can be change to: “Soil erosion research provides the essential means for humans to use the earth's resources appropriately and preserve and restore environmental conditions.”

Lines 45-47: “Several studies have shown that land use/cover change, such as industrialization, inappropriate agricultural management, urbanization, overgrazing and deforestation, may increase soil erosion rates to a large extent”.

Maybe is better to say: “Several studies have shown that land use/cover change, due to industrialization, inappropriate agricultural management, urbanization, overgrazing and deforestation, may increase soil erosion rates to a large extent”.

Line 59: “Soil erosion models have been an effective method for detecting and predicting soil loss”

I think it might be better

“Soil erosion models provide effective methods for detecting and predicting soil loss”

Line 73-75: “China is one of the most populous countries in the world, and soil erosion, caused mainly by intense human activities and natural factors such as deforestation, urbanization, land use change, regional meteorology, geology and topography, has become a national environmental problem.”

It can change to:

“China is one of the most populous countries in the world and soil erosion caused mainly by intense human activities and natural factors such as deforestation, urbanization, land use change, regional meteorology, geology and topography. Therefore, it is has become a national environmental problem.”

Author Response

Reply to the comments

 

Dear Editor and Reviewers:

We thank the referees for their positive evaluation of our manuscript and for their insightful comments, which have been a great help in improving the quality of our paper. We carefully revised the paper according to these comments and suggestions. The related parts of the paper have been rewritten and improved. For your easy reading and evaluation, the changed parts are marked using RED COLORED text in the revised version. Please note that the line numbers mentioned in reviewers’ comments refer to the original version, while in our reply refer to the revised version.

 

We hope the revised version is satisfactory for publication, and of course, we are more than happy to improve the paper again according to further comments and suggestions they might come.

 

Reply to the comments from Reviewer #5

Main comment for the full paper:

The article “Soil erosion characteristics in tropical island watersheds based on CSLE model: discussion of driving mechanisms”, evaluates the consequences of soil erosion of Hainan Island in China. The article can be published, but in my opinion needs some corrections in the way of presentation. Additionally, the are a few mistakes in English.

Reply: Thank you for your positive evaluation in general and professional comments and suggestions, which have been taken full consideration in the revised version. And below are our point-by-point replies to your specific comments and suggestions.  

Detailed comments:

Abstract

The abstract should be expanded and introduce the reader to the philosophy and the findings of the article. Also, some parts must be rephrased. Particularly, at lines 14,17 and 25, the symbol “:” should be removed. The authors are advised to provide a text with flow.

Reply: Thank you for your kind suggestion. We have revised the abstract section from the perspectives of novelty and research significance. Following your suggestions, we have removed unnecessary semicolons and rephrased sentences to enhance clarity and fluency of expression.

 

1. Introduction

The introduction is clear and to the topic. However, lines 115 – 130 would be better to be removed from introduction and presented at the methodology.

Reply: Thank you for your kind suggestion. We have taken your suggestion and included the mentioned section in the method part. Please refer to lines 174-184 of the revised version for detailed information.

 

2. Study area

The authors can add some extra information concerning the population or some general information about the climate and the anthropogenic factors that occur.

Reply: Thank you for your kind suggestion. We have added a description in the study area section highlighting the differences in human activities and climate conditions between the study area, the eastern region, and the western region of Hainan Island. This emphasizes the importance of the study area and the necessity of the research. Please refer to lines 160-163.

 

3. Methodology

Please provide a paragraph referring to the data origin and sources

Also, the symbol “*” in the equations does not mean anything. Please replace it with “×” or “·”

Reply: Thank you for your reminder and kind suggestion. We have added a paragraph in the method section to provide information about the data sources, and we have made the requested modification of replacing "*" with "x". Please refer to lines 187-196 and the section on formulas for detailed information.

 

4. Result analysis

Line 313: please number the figure

Reply: Thank you for your reminder. We have assigned numbers to the figures you indicated, as indicated in lines 390-391.

 

4.4 Analysis of the influence of human activities on soil water erosion

I have the opinion the theoretical background of the transfer matrix (table 2) should be presented in methods.

Also, the authors should also explain in methods how the table 3 occurred

The paragraphs 5 and 6 are based to the findings of the survey, personally I have no comments or changes for them.

Reply: Thank you for your kind suggestion. We have added a description of the transfer matrix method in the Methods section and explained how Table 3 was generated. Please refer to lines 265-269 for specific details.

 

Comments on the Quality of English Language

Concerning to the English style I have the following comments

Lines 31-32: “Soil erosion research provides an essential medium for humans to use the earth's resources appropriately and preserve and restore environmental conditions.”

Can be change to: “Soil erosion research provides the essential means for humans to use the earth's resources appropriately and preserve and restore environmental conditions.”

Reply: Thank you for your kind suggestion. We accept your modifications. Please refer to lines 36-37 for the details.

 

Lines 45-47: “Several studies have shown that land use/cover change, such as industrialization, inappropriate agricultural management, urbanization, overgrazing and deforestation, may increase soil erosion rates to a large extent”.

Maybe is better to say: “Several studies have shown that land use/cover change, due to industrialization, inappropriate agricultural management, urbanization, overgrazing and deforestation, may increase soil erosion rates to a large extent”.

Reply: We appreciate your kind suggestion and have incorporated the modifications accordingly. For specific details, please refer to lines 50-52.

 

Line 59: “Soil erosion models have been an effective method for detecting and predicting soil loss”

I think it might be better. “Soil erosion models provide effective methods for detecting and predicting soil loss”

Reply: Thank you for your valuable suggestion. We appreciate it and have accepted your modifications. Please refer to line 64 for the specific details.

 

Line 73-75: “China is one of the most populous countries in the world, and soil erosion, caused mainly by intense human activities and natural factors such as deforestation, urbanization, land use change, regional meteorology, geology and topography, has become a national environmental problem.”

It can change to:

“China is one of the most populous countries in the world and soil erosion caused mainly by intense human activities and natural factors such as deforestation, urbanization, land use change, regional meteorology, geology and topography. Therefore, it is has become a national environmental problem.”

Reply: We appreciate your thoughtful suggestion. We have accepted the modification. Please refer to lines 124-126 for the specific details.

 

 

 

Author Response File: Author Response.docx