Does Adaptation to Saltwater Intrusion Improve the Livelihoods of Farmers? Evidence for the Central Coastal Region of Vietnam

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The presented article is devoted to an urgent problem and contains signs of novelty and scientific value. The statement of the problem and the research correspond to the subject matter of the journal and the editorial policy. The shortcomings of the work are not significant, but clarification is required.

1) The authors did not reveal the meaning of setting the problem of adapting management methods to environmental changes. The design of the study of farmers' adaptive behavior is clear. But the environmental consequences of this behavior are not shown.

2) Formal models are described in great detail. It would be possible to slightly reduce the descriptive statistics, expanding the summary part. Not all models used provide high-quality results. Perhaps the trial portion of the study should be shortened.

3) Important conclusions describing the summary part of the study are not fully justified by the calculation part. It appears that some conclusions contradict the calculated data. For example, the significance of the impact on social indicators is low. The economic returns of new management methods cannot be justified with such low samples that the study allows us to obtain.

4) The authors mention a focus group study, but the descriptive part does not contain its results and results.

Author Response

Comment 1: The authors did not reveal the meaning of setting the problem of adapting management methods to environmental changes. The design of the study of farmers' adaptive behavior is clear. But the environmental consequences of this behavior are not shown.

Response 1: We agree with this comment. As mentioned in the paper (line 107-113, line 752-759), evaluating the problem of adapting management methods to environmental changes is impossible for the study due to the lack of data. This is also a limitation of our study. More explanation of this point has been added in introduction ( line 80-84)

 

Comment 2: Formal models are described in great detail. It would be possible to slightly reduce the descriptive statistics, expanding the summary part. Not all models used provide high-quality results. Perhaps the trial portion of the study should be shortened.

Response 2: We agree with this comment. Descriptive statistics tables have been shorterned and summary part has been expanded. Two descriptive statistics table have been replaced in Appendix part. More summury parts have been added in the text.

 

Comment 3: Important conclusions describing the summary part of the study are not fully justified by the calculation part. It appears that some conclusions contradict the calculated data. For example, the significance of the impact on social indicators is low. The economic returns of new management methods cannot be justified with such low samples that the study allows us to obtain.

Response 3: Thank you for pointing this out. I/We agree with this comment. The limitation related to size sample has been introduced in conclusion part (line 746-747). However, the impact on economic indicators are almost statistically significant and the impact on social indicators is low but still statistically significant ( Table 3 and Table 5), meaning that the results of our study still can be the reference for the policy implications. We have revised the text that only focus on the statically significant indicators.

 

Comment 4: The authors mention a focus group study, but the descriptive part does not contain its results and results.

Response 4: We agree with this comment. The descriptive part contain the results of FGDs is added in appendix part.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study's topic is interesting and may be considered for publication following major revisions. I have provided some suggestions that may be helpful for the authors in improving this manuscript.

1. One line 160, page 4, please elaborate on the relationship between children attending school and the implementation of SWI.
2. On line 205, page 5, which source reports these communes at different levels of SWI?
3. On line 217, page 5, please clarify which province the named district belongs to. For example, Quang Dien (Quang Nam Province).
4. On lines 442-443, page 12, how is the total net income calculated? Is it based on total revenue and cost? If so, why is the cost not mentioned here?
5. In Table 3 on page 12, what does "sao" mean? Is it a new measurement unit? For international readers, please use a widely recognized measurement unit. This allows readers to easily understand the area size and net farm income, and facilitates comparison to other countries or regions.
6. What are the policy recommendations? What will happen if farmers recognize the insignificance of implementing new rice varieties, discontinue rice farming, and switch to other crops or shrimp farming or lotus-fish farming? Please provide arguments on this point as it has implications for food security.
7. The number of observations in Table 4 differs from the number of observations (adapters = 185, non-adapters = 229) in Tables 6 and 7. Please provide an explanation.
8. On lines 528-529, page 15, why does switching to new rice varieties decrease net farm income? Please explain. Is a difference in net income of 512 thousand VND per /sao/per year significantly lower? If so, please express this as a percentage decrease for easier comprehension.
9. On lines 572-573, page 16, how did you compare net farm income between rice farming and shrimp farming? Did you calculate the net income for shrimp farming based on one year's cost and revenue only? How about the initial investment and equipment costs for shrimp farming in the first year? The same question applies to the income calculation (i.e., costs, investment costs) for the lotus-fish model.
10. On line 640, page 17, how can the forecasts for future SWI developments be improved? Please provide more details.

Comments on the Quality of English Language

This manuscript is well-written.

Author Response

Dear reviewer,

We would first like to thank all valuable feedback that will undoubtedly improve the quality of our work. We respond to the different issues that were raised by reviewer in a reaction below. You will find our responses in red.

Best regards,

Thi Dieu Linh Nguyen, Bart DeFloor, Brent Bleys and Stijn Speelman

 

Comment 1: One line 160, page 4, please elaborate on the relationship between children attending school and the implementation of SWI.

Response 1: We agree with this comment. Explanation has been added (line 170-173)

Comment 2: On line 205, page 5, which source reports these communes at different levels of SWI?

Response 2: We agree with this comment. Source of report has been added (line 218-219)

Comment 3: On line 217, page 5, please clarify which province the named district belongs to. For example, Quang Dien (Quang Nam Province).

Response 3: We agree with this comment. Clarification has been added (line 213-215)

Comment 4: On lines 442-443, page 12, how is the total net income calculated? Is it based on total revenue and cost? If so, why is the cost not mentioned here?

Response 4: Thank you for pointing this out. For rice, papyrus and vegetables method, farmers calculated by themselves the total net income and then reported to the interviewer. It was impossible to collect data related to revenue and cost because farmers did not record the data. We calculated the net income of shrimp farming based on the time horizon of 5 years because the investment and equipment need five years of depreciation, then we calculated the total cost of five year and then get the average cost per year. The same method of calculation was applied for lotus-fish model.

Cost not mentioned here because it is not outcome variable.

Comment 5: In Table 3 on page 12, what does "sao" mean? Is it a new measurement unit? For international readers, please use a widely recognized measurement unit. This allows readers to easily understand the area size and net farm income, and facilitates comparison to other countries or regions.

Response 5: Thank you for pointing this out. The footnote is added to explain the meaning of sao unit (page 10)

Comment 6: What are the policy recommendations? What will happen if farmers recognize the insignificance of implementing new rice varieties, discontinue rice farming, and switch to other crops or shrimp farming or lotus-fish farming? Please provide arguments on this point as it has implications for food security.

Response 6: Thank you for pointing this out. We agree with this comment. The arguments have been added (line 723-731, line 743-747)

 

 

Comment 7: The number of observations in Table 4 differs from the number of observations (adapters = 185, non-adapters = 229) in Tables 6 and 7. Please provide an explanation.

Response 7: In table 4, we run the probit model by two ways:

Way 1 (Model 1): There are two groups: adapters (185 observations) and non-adapters (229 observations)

Way 2: (Model 2): There are five groups

• Group 1: adapters of  NR (89 observations) and non-adapters (229 observations), total observations are
• Group 2: adapter of PP (29 observations) and non-adapters (229 observations), total observations are 258
• Group 3: adapter of SR (46 observations) and non-adapters (229 observations), total observations are 275
• Group 4: adapter of VG (10 observations) and non-adapters (229 observations), total observations are 239
• Group 5: adapter of LF (11 observations) and non-adapters (229 observations), total observations are 240

                       

 

Comment 8: On lines 528-529, page 15, why does switching to new rice varieties decrease net farm income? Please explain. Is a difference in net income of 512 thousand VND per /sao/per year significantly lower? If so, please express this as a percentage decrease for easier comprehension.

Response 8: Thank you for pointing this out. We agree with this comment. Switching to new rice varieties decreases the net farm income because new rice varieties have lower yield than normal rice. The difference in net income of 512 thousand VND per /sao/per year significantly lower. Expressions of difference by percentage have been added (line 593-610)

Comment 9: On lines 572-573, page 16, how did you compare net farm income between rice farming and shrimp farming? Did you calculate the net income for shrimp farming based on one year's cost and revenue only? How about the initial investment and equipment costs for shrimp farming in the first year? The same question applies to the income calculation (i.e., costs, investment costs) for the lotus-fish model.

Response 9: Thank you for pointing this out. We agree with this comment. In this table, we did not compare net farm income between rice farming and shrimp farming, we did compare net farm income between each method of adaptation and normal rice farming (non-adapter)

We calculated the net income of shrimp farming based on the time horizon of 5 years because the investment and equipment need five years of depreciation, then we calculated the total cost of five year and then get the average cost per year. The same method of calculation was applied for lotus-fish model.

Comment 10: On line 640, page 17, how can the forecasts for future SWI developments be improved? Please provide more details.

Response 10: We agree with this comment. More details have been added (line 718-721)

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

This revised manuscript could be considered for publication after minor revisions.

1. Check typos in the following sentence:
   • Line 209, Page 5: (Quang Nam provicne)
2. ”Sao” can be mentioned as a local unit that local farmers in Central regions use. However, I think you should use the popular unit of hectare instead of the local measurement of sao in the table. Also, in Line 493, Page 11: The authors mentioned USD = 21,000 VND. Do you think the currency in the table should be changed to USD/ha for international readers to easily compare farmers' net income in Vietnam with those in other countries?
3. Line 559-560, Page 13: "The ATT between each adaptation method individually and the control group of non-559 adapters are presented in Table 4, from which the following conclusions can be drawn." I think these conclusions can be drawn from Table 5, not Table 4. Please check it again. Additionally, I think it would be better if you give more explanation on how you estimated the results in Table 5, for instance, applying PSM (i.e., Kernel matching), to the above sentence.
4. Line 593-596, Page 14: The authors mentioned USD = 21,000 VND. Do you think the currency in the table should be changed to USD/ha for international readers to easily compare farmers' net income in Vietnam with those in other countries?
5. Line 679-682, Page 15: "In Mekong River Delta, farmers have been trained to install application on smart phone that automatically monitor water sources as well as receive information about water levels in the river, pH level, water temperature and salinity. This new technique helped farmers proactively and effectively respond to salinity intrusion.". Why do you mention farmers in the Mekong River Delta here? Is this result from your study or another study? If you want to make a comparison, please give more information on the current situation of farmers in the Central Coastal Region of Vietnam, your study area.

Author Response

Dear reviewer,

We would first like to thank all valuable feedback that will undoubtedly improve the quality of our work. We respond to the different issues that were raised by reviewer in a reaction below. You will find our responses in red.

Best regards,

Thi Dieu Linh Nguyen, Bart DeFloor, Brent Bleys and Stijn Speelman

 

Comment 1: Check typos in the following sentence:Line 209, Page 5: (Quang Nam provicne)

Response 1: We agree with this comment. Typos is checked and corrected

Comment 2: ”Sao” can be mentioned as a local unit that local farmers in Central regions use. However, I think you should use the popular unit of hectare instead of the local measurement of sao in the table. Also, in Line 493, Page 11: The authors mentioned USD = 21,000 VND. Do you think the currency in the table should be changed to USD/ha for international readers to easily compare farmers' net income in Vietnam with those in other countries?

Response 2: We agree with this comment. All unit thousand VND/ sao have been changed to USD/ha in the whole text

Comment 3: Line 559-560, Page 13: "The ATT between each adaptation method individually and the control group of non-559 adapters are presented in Table 4, from which the following conclusions can be drawn." I think these conclusions can be drawn from Table 5, not Table 4. Please check it again. Additionally, I think it would be better if you give more explanation on how you estimated the results in Table 5, for instance, applying PSM (i.e., Kernel matching), to the above sentence.

Response 3: We agree with this comment. We correct Table 5 instead of Table 4 and added more explaination of PSM method (Line 679-680)

Comment 4: Line 593-596, Page 14: The authors mentioned USD = 21,000 VND. Do you think the currency in the table should be changed to USD/ha for international readers to easily compare farmers' net income in Vietnam with those in other countries?

Response 4: We agree with this comment. All unit thousand VND/ sao have been changed to USD/ha in the whole text

Comment 5: Line 679-682, Page 15: "In Mekong River Delta, farmers have been trained to install application on smart phone that automatically monitor water sources as well as receive information about water levels in the river, pH level, water temperature and salinity. This new technique helped farmers proactively and effectively respond to salinity intrusion.". Why do you mention farmers in the Mekong River Delta here? Is this result from your study or another study? If you want to make a comparison, please give more information on the current situation of farmers in the Central Coastal Region of Vietnam, your study area.

Reponse 5: We agree with this comment. What we want to mention is this new technique is only applied in Mekong river delta, not yet in our study area. The text has been resived.

Author Response File: Author Response.pdf