Landscape Pattern Changes Affect Runoff and Sediment Yield in the Nandong Underground River System in Southwest China
Round 1
Reviewer 1 Report
This paper presents a spatial analysis study in a karst underground river system in China. The authors used 8 landscape pattern indices to represent soil and water conservation capacity of the study area. Then the authors evaluated the relationships between the observed runoff/sediment yield and landscape pattern indices using several statistical analyses. The results show that the ecological restoration project in the study area is effective. On the other hand, the soil and water conservation capacity has declined in urban areas. The study is on a topic of interest to the audience of this journal. I have the following comments that I hope the authors could address in their revision.
Specific comments:
1. The writing of this paper needs some major improvement. The method section (section 2) is not clear.
2. Both “VTF” and “VT” are used in this paper, which is confusing.
3. Lines 146-148, Figure 2: It will be helpful if the authors could add the measurement locations of runoff and sediment in Figure 2.
4. Lines 157-158: This sentence explains the reasoning behind the VT equation, which is a bit arbitrary. It would be helpful if the authors could add more references and more in-depth theoretical explanation here to support their proposed VT equation.
5. Figure 11: It is not clear how this map is generated. The procedure of this part in section 2 (Lines 191-204) is hard to follow.
6. Conclusions: This section is not informative. It is better to use descriptive language to explain the major findings of the study, instead of listing numbers from statistical analyses.
Author Response
- The writing of this paper needs some major improvement. The method section (section 2) is not clear.
A1：We have carefully reorganized the method section.In order to understand the process of the method in the article，we add a paragraph describing the method flow (line.193-line.199), change Figure 1 to Figure 2, moving from Introduction to Method (line.201), and add instructions 2.3.1-2.3.5 in the figure 2. Modified the 2.3.1 statement(line.205-line.216). Transpose tab.2(line.218) and tab.3(line.258).
- Both “VTF” and “VT” are used in this paper, which is confusing.
A2: To avoid ambiguity, VT was changed to (VTF1~5). VTFi is the level of VTF. There are 5 levels in this article, namely VTF1, VTF2, VTF3, VTF4 and VTF5. And change the equation involving VT into VTF equation in the article, see line (lines212 and line.301).
- Lines 146-148, Figure 2: It will be helpful if the authors could add the measurement locations of runoff and sediment in Figure 2.
A3: Change Figure 2 to Figure 1, add sediment and runoff collection locations at Figure.1 outlet.(line.168)
- Lines 157-158: This sentence explains the reasoning behind the VT equation, which is a bit arbitrary. It would be helpful if the authors could add more references and more in-depth theoretical explanation here to support their proposed VT equation.
A4: We changed the structure of the method and added four references [7,19,20,23], mainly explaining why these three underlying surface factors were selected to support the VTF equation proposed in the paper (line.193-line.196). We also describe the reasoning behind the VTF equation in the second paragraph of the introduction. (line.84-line.91)
- Figure 11: It is not clear how this map is generated. The procedure of this part in section 2 (Lines 191-204) is hard to follow.
A5: I am very sorry; We do not have a good illustration of how Figure 11 and Table 5 are generated. Now, we added (line.427-line.430, line.437) to explain the process.
- Conclusions: This section is not informative. It is better to use descriptive language to explain the major findings of the study, instead of listing numbers from statistical analyses.
A6: We have rewritten the conclusions, which correspond to the two scientific questions raised in this paper and the conclusions of the research in this paper. (line.575-line.594)
Reviewer 2 Report
(1)line 155, for the index of PD,LPI,LSI,IJI,CONNECT,DIVISION,SHDI,AI, how to calculate,or formula?
(2)line 161, Eucdistance ,Slope and NDVI to water and soil conservation capacity is uniform ,is it reasonable？
（3）In figure 3，why slope ,NDVI ,Euclidean range from 0 to 1,however VT value only from 0.10 to 0.86 ?
(4)line 213, K=(1,2...3) should changed to K=(1,2,...,3)
(5)line 262, PLS should be PLSR
Author Response
1.line 155, for the index of PD,LPI,LSI,IJI,CONNECT,DIVISION,SHDI,AI, how to calculate,or formula?
A1: These indices were calculated using FRAGSTATS4.2 software and we added a table A1 to the calculation formula. Put in the appendix A.（line.612）
2.line 161, Eucdistance ,Slope and NDVI to water and soil conservation capacity is uniform ,is it reasonable？
A2: Many thanks to the reviewer’s question. At the beginning, we intended to conduct an exploratory study, because we could not know the proportion of each factor, so we used the average method. We found the average method can meet the research requirements. In the future, we will try to use a better method to calculate the weight of each factor, so as to conduct more accurate fitting.
3.In figure 3，why slope ,NDVI ,Euclidean range from 0 to 1,however VT value only from 0.10 to 0.86 ?
A3: Although the values of all three ranges from 0 to 1, they cannot be both 0 or 1. 0.1 < 1/3 (slope +NDVI+ Euclidean value) < 0.86. Thus, the minimum value of VTF is 0.1 and the maximum value is 0.86.
4.line 213, K=(1,2...3) should changed to K=(1,2,...,3)
A4: The k value symbol behind the PLSR formula has been corrected(line.292)
5.line 262, PLS should be PLSR
A5: The PLS in Figure 6 has been changed to PLSR(line.369).
Reviewer 3 Report
I revised the ms. "Landscape pattern changes affecting runoff and sediment yield in the Nandong underground river system in Southwest China" and in my opinion, the ms. is well written and need minor suggestions.
* Table 2: there is some abbreviattions...please, write the meanings!
*Fig. 3, 4 and 11: improve the figure. It´s difficult to read!
* Figure 2: has letters "A", "B" and "c" and it´s not in the figure title.
Author Response
* Table 2: there is some abbreviattions...please, write the meanings!
Table 2 (line218) and Table 3(line.258) switch places, and the new table 3 (line.258) adds the full name of each landscape factor.
*Fig. 3, 4 and 11: improve the figure. It´s difficult to read!
We checked and found that the text and scale in many of the images did not match. We modified the images and adjusted the text size to improve the readability of the images.
* Figure 2: has letters "A", "B" and "c" and it´s not in the figure title.
Figure 2 has been changed to Figure 1 with the addition of A, B, and C in Figure 2 .（line.168）
Reviewer 4 Report
This paper is very interesting and it's well written. Authors should indicate the software with which the analysis has been carried out. The results are very interesting, and this paper is adecuated to publish in this journal. I suggest that you test the results instead of the mean with the median.
1. What is the main question addressed by the research? à Landscape pattern changes affecting runoff and sediment yield in the Nandong underground river system.
2. Do you consider the topic original or relevant in the field? I think, this topic is relevant and original. Does it address a specific gap in the field? à It is not my field of research, to know for sure if it is pioneering or not. The methodology is known to me and used in other fields.
3. What does it add to the subject area compared with other published material? à
4. What specific improvements should the authors consider regarding the methodology? What further controls should be considered? à The methodology used using Vegetation-topographic factor (VTF) was constructed using the Normalized vegetation index (NDVI), Digital Elevation Model (DEM).
5. Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? à In my opinion, no. The report presents a brief summary of the results but does not comment in detail on the conclusions drawn. Perhaps the discussion and conclusions section should be rethought.
6. Are the references appropriate? à I think they are adequate
7. Please include any additional comments on the tables and figures. à The caption of the tables and figures should be self-explanatory and more detailed, otherwise they do not provide information. It is not just putting tables and/or figures for the sake of it. They accompany the text and help to better understand the work.
Author Response
Responses to Reviewers 4
This paper is very interesting and it's well written. Authors should indicate the software with which the analysis has been carried out. The results are very interesting, and this paper is adecuated to publish in this journal. I suggest that you test the results instead of the mean with the median.
A: In this paper, we add VTLI software FRAGSTATS4.2 (line.252) and ARCGIS (line.213) for image processing. I also appreciate the reviewer's suggestion of using median as test result. We carefully check the full text, perhaps in each VTF classification, we can use the median to express specific size of each level, and our data is continuous, we will be in use the median instead of the mean deeper thinking.
- What is the main question addressed by the research? à Landscape pattern changes affecting runoff and sediment yield in the Nandong underground river system.
A1:
This research is worth investigating, and we found some issues that need to be addressed. Because the effect of soil and water conservation governance in fault basins and various landforms is unclear, it is urgent to evaluate the trend of soil and water conservation capacity. Therefore, the VTF index we constructed represents the soil and water conservation capacity. The trend method is used to analyze the change trend of soil and water conservation capacity, and the Hurst index method is used to analyze whether the change trend of soil and water conservation capacity is sustainable. Secondly, the relationship between the various landscape indicators (underlying surface) of the watershed and the yield of runoff and sediment is not clear, and it is impossible to take corresponding landscape management measures for the restoration of specific watersheds. So, we constructed 8 indicators of VTLI on the basis of VTF. Pearson method was used to analyze the correlation between 8 indexes and runoff (sediment yield). The PLSR method was used to analyze the changes in the importance of VTLI and runoff (sediment yield) during three periods. Targeted landscape pattern management to reduce soil erosion.
- Do you consider the topic original or relevant in the field? I think, this topic is relevant and original. Does it address a specific gap in the field? à It is not my field of research, to know for sure if it is pioneering or not. The methodology is known to me and used in other fields.
A2:
I’m very agreed with reviewer’ opinion. I think the topic is relevant and original. The detail is in the third comment’s answer.
- What does it add to the subject area compared with other published material? À
A2 and A3：
The traditional landscape pattern index is based on land use generated by remote sensing, while the landscape pattern index is not limited to land use. We constructed VTF based on several factors affecting runoff and sediment yield, such as distance from water system, NDVI, terrain, etc. The new method is flexible, and land use cannot reflect the influence of terrain and other factors, but as an established result.
The time resolution of the land use method is not high enough, and the values are not continuous. The purpose of our research is to evaluate the change trend of NURS soil and water conservation capacity. We need the analysis of space and high temporal resolution.
In the above two aspects, we have enriched and deepened the research in the field of landscape runoff and sediment yield.
- What specific improvements should the authors consider regarding the methodology? What further controls should be considered? à The methodology used using Vegetation-topographic factor (VTF) was constructed using the Normalized vegetation index (NDVI), Digital Elevation Model (DEM).
A4:
Next, we will try to find a more reasonable ratio of NDVI, DEM and Euclidean distance. In addition, more factors affecting runoff and sediment yield can be added to make the calculation result more accurate.
- Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? à In my opinion, no. The report presents a brief summary of the results but does not comment in detail on the conclusions drawn. Perhaps the discussion and conclusions section should be rethought.
A5:
In the discussion section, in order to answer the scientific questions raised in this paper and the research results: 4.1) Explain why this kind of research is carried out, and how it is different from the traditional landscape pattern index research, which scholars have also conducted similar research, how does this method help the problems to be solved, and how feasible and effective is the new framework? 4.2) In addition to analyzing the influence of the 8 indicators of VTLI on the runoff and sediment yield in Nandong watershed, the explanatory power of VTLI landscape indicators on runoff and sediment yield was added. To answer the scientific question raised, how does the landscape pattern affect the yield of runoff and sediment, and whether it has played a positive role in the restoration of watershed management. 4.3) The VTF results we obtained, combined with the urbanization process after 2002, how the ecological engineering after 2008 affected the soil and water conservation capacity in space and time from two aspects.
We have rewritten the conclusions, which correspond to the two scientific questions raised in this paper and the conclusions of the research in this paper. (line.575-line.594).
- Are the references appropriate? à I think they are adequate
A: I agree reviewer’ opinion.
- Please include any additional comments on the tables and figures. à The caption of the tables and figures should be self-explanatory and more detailed, otherwise they do not provide information. It is not just putting tables and/or figures for the sake of it. They accompany the text and help to better understand the work.
To make the meaning of the pictures and tables clear. We have made several changes:
- We checked and found that the text and scale in many of the images did not match. We modified the images and adjusted the text size to improve the readability of the images.
- We added a table A1 to the calculation formula. Put in the appendix A.（612）
- In Figure 2, we added (A)Yunnan is located in China,(B) NUSR is located in Yunnan,and(C) Map of NURS. （168）
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
The authors did a good job on incorporating reviewers’ comments in the manuscript and the improvement is significant. I have no further comments.
