Impact Assessment of Livestock Production on Water Scarcity in a Watershed in Southern Brazil^†

Round 1

Reviewer 1 Report

Review of manuscript: water-2671911

Recommendation:      Accept after minor revision (corrections to minor methodological errors and text editing)

 The reviewed manuscript, “Impact assessment of livestock production on water scarcity in a watershed in southern Brazil”, authors: Sofia Helena Zanella Carra, Katrin Drastig, Julio Cesar Pascale Palhares, Taison Anderson Bortolin, Hagen Koch, Vania Elisabete Schneider, is an interesting study on assessment of water scarcity associated with livestock (poultry, pig, and milk) production in a watershed in southern Brazil. The study is interesting and potentially could contribute to the research field. The topic is in line with the scope of the journal and may be of interest to the readers. Therefore, I recommend its publication in Water.

 The research in the present paper is complex and focuses on evaluating the impact of livestock production on water scarcity in Brazil, providing scientific evidence to support decision-making on the water management in animal production in Brazil and consequently achieving a more sustainable livestock supply chain. The assessment of water scarcity supports water risk management and decision-making.

 The subject addressed in the paper is original, topical and relevant to the field considering the growing challenges for the livestock sector worldwide, that affect global resources and environment. At the same time, the author carried out the study on an important area that comprises the partial territory of four cities and where 115 farms with broiler, pig and dairy productions were located. The paper has a well-organized structure based on a large set of data, and the extensive discussion of a significant number of aspects related to water scarcity impact assessment.

 In conclusion section the author emphasizes the most pronounced findings of the study in accordance with the proposed objectives and the research carried out and opportunities to inform future research and also focus on important message to reader based on the obtained findings.

 The author has carried out an extensive literature study, in order to justify the importance and the choice of the research topic, proven by the number of adequately selected references.

 I have only a few minor remark:

L 273-273: the authors state that LWC was higher in months with higher temperatures in summer, such as January and February. It is not clear if it is about the summer months or January and February. Please rephrase.

Author Response

RESPONSE TO REVIEWER 1

General Comment: The reviewed manuscript “Impact assessment of livestock production on water scarcity in a watershed in southern Brazil” is an interesting study on assessment of water scarcity associated with livestock (poultry, pig, and milk) production in a watershed in southern Brazil. The study is interesting and potentially could contribute to the research field. The topic is in line with the scope of the journal and may be of interest to the readers. Therefore, I recommend its publication in Water.

Suggestions and Comments:

L 273-273: the authors state that LWC was higher in months with higher temperatures in summer, such as January and February. It is not clear if it is about the summer months or January and February. Please rephrase.

We appreciate your comment. The LWC was higher in summer, especially in December and January. The sentence was rephrased.

Reviewer 2 Report

In abstract, mentioned scenarios still don’t define and are vague for reader.

Literature review could be up to date using manuscript about water-food nexus.

Line 113: innovation and key points of manuscript should be define in better form and comparatively. Also, livestock production has impact on water scarcity or water scarcity will limit production activities? Main goal of manuscript should be define clearly. In many studies, water allocation models define water amount in any sector.

Based on water scarcity, lack of water supply and its effect on production has been considered or production always must be without restriction? Result of research is an assessment for managing water or managing production?

Line 198: available water is surface water or ground water or both of them? If there is not any limitation in consumption, for example withdrawal of ground water, assessment of water scarcity is meaningless.

Line 446-447: there are any limitation in groundwater withdrawal?

Data in this paper for example Monthly Human Water Consumption (fig 3), is average of monthly values, or value of a specific month.

Author Response

RESPONSE TO REVIEWER 2

Suggestions and Comments:

In abstract, mentioned scenarios still don’t define and are vague for reader.

We appreciate your comment. The description of the scenarios was improved in the abstract where the input data used to analyse the scenarios is now mentioned.

Literature review could be up to date using manuscript about water-food nexus

The literature review was structured with a focus on presenting the main challenges faced in Brazil due to water stress and the importance of the FAO LEAP Guidelines as a methodology that aims to harmonize the assessment of water scarcity. The literature review was positively evaluated by the other reviewers.

Line 113: innovation and key points of manuscript should be define in better form and comparatively. Also, livestock production has impact on water scarcity or water scarcity will limit production activities? Main goal of manuscript should be define clearly. In many studies, water allocation models define water amount in any sector.

Indeed, both impacts are assessed in this study: the contribution of livestock production to water scarcity and the potential environmental impact resulting from water uses (e.g. animal production) in the study area. This sentence presents the goal of the water scarcity impact assessment according to the definition presented in the FAO LEAP Guidelines (2019). On this basis, the sentence in line 113 was improved.

Based on water scarcity, lack of water supply and its effect on production has been considered or production always must be without restriction? Result of research is an assessment for managing water or managing production?

Thank you for your comment.The water scarcity footprint (WSF) was calculated considering water consumption for all water uses in the watershed without restrictions, following the AWARE and BWSI methods. The results showed low water scarcity in the watershed for all water uses (animal production and human water consumption). Decision-makers can use these results to establish new rules or programs aimed at reducing water scarcity (water management) and can signal to farmers the need to implement best practices to improve water productivity, producing more with less water (production management). The combination of water productivity (farm basis – production management) and water scarcity (watershed basis – water management) was highlighted in the paragraph from Lines 90 to 97.

Line 198: available water is surface water or ground water or both of them? If there is not any limitation in consumption, for example withdrawal of ground water, assessment of water scarcity is meaningless.

As presented in session 2.2.2, water availability was calculated only for surface water. Groundwater was not considered in this study due to the lack of data and consequent high data uncertainty, as explained in Line 308. The calculations presented in this study follow the AWARE and BWSI methods, which are recognized internationally.

Line 446-447: there are any limitation in groundwater withdrawal?

The reasons for not considering groundwater in this study, despite its representativeness, were presented in Line 308. The authors therefore encourage the integration of groundwater in further studies.

Data in this paper for example Monthly Human Water Consumption (fig 3), is average of monthly values, or value of a specific month.

 The monthly results of total water consumption throughout the year are shown in Figure 3. This explanation was included in Line 272.

Author Response File: Author Response.pdf

Reviewer 3 Report

COMMENTS ON MANUSCRIPT ID: water-2671911

The manuscript presents “Impact assessment of livestock production on water scarcity in a watershed in southern Brazil”, which is interesting. The subject addressed is within the scope of the journal. I enjoyed this paper, and liked the approach to evaluate livestock production on water scarcity in a watershed.

The following points should be addressed before the consideration for publication.

-          Instead of Figure 1. Location of the study area in the Taquari-Antas basin. A map prepared in a more professional map program should be preferred.

-          Mention about limitations of your study if you have any in conclusion section.

It would be appropriate if a comparison table was made with the values found around the world.

Author Response

RESPONSE TO REVIEWER 3

General Comment: The manuscript presents “Impact assessment of livestock production on water scarcity in a watershed in southern Brazil”, which is interesting. The subject addressed is within the scope of the journal. I enjoyed this paper, and liked the approach to evaluate livestock production on water scarcity in a watershed.

Suggestions and Comments:

Instead of Figure 1. Location of the study area in the Taquari-Antas basin. A map prepared in a more professional map program should be preferred.

We appreciate your comment. Two previous studies carried out considering data from the same farms and study area were previously published. They are mentioned in Line 151 and Line 154, and both publications present the water productivity assessment of pig, poultry, and dairy milk, which also followed the methodology proposed by the FAO LEAP Guidelines (2019). A similar Figure with the farm's location was published in these previous studies. Therefore, we used this figure to facilitate the readers who want to read the role case study (three publications). A figure with a higher resolution was included in the latest version of this manuscript.

Mention about limitations of your study if you have any in conclusion section

The main limitation of this study was the lack of groundwater data to assess the water availability and the consequent high data uncertainty, as explained in Line 308. Encouraging further studies that integrate groundwater availability was included in the conclusion as a recommendation.

It would be appropriate if a comparison table was made with the values found around the world.

We appreciate your comment. As presented in Line 421, the different methods, units and other characteristics used in the studies that have assessed water scarcity do not allow for comparison between them. This is the main reason why the FAO LEAP Guidelines (2019) aim to harmonize these methods and promote a minimum alignment of results. Therefore, we have not included a table to avoid misunderstandings when interpreting the results.

Author Response File: Author Response.pdf

Reviewer 4 Report

General comments:

The manuscript presented an interesting study related to assessment of the water scarcity of livestock production in southern Brazil. The introduction is well written, presenting a good state of art. However, the methodology is very poor, the authors need to present more details about the sources of data, because in the discussion in results they are talking about data from interview and data from literature, but the authors to put a Table presenting the sources of each information presented. The sections (2.2 Input data) need to be written, for example the authors in section 2.2.2. Water Availability are talking about different scenarios however, details of those scenarios are presented in the last section 2.4 Scenario settings, the paper needs to be consistence. The authors need to presented information related the climate in region (Temperature and rainfall) to complete the information discussed.

Specific comments:

Line 133: Figure 2: the resolution needs to be improved.

Line 148: how do the authors calculate cleaning water consumption from the literature? you are talking about the part of the cleaning water consumption?

Line 163: Put the Table 1 mentioned just after the paragraph where you mentioned it for the first time.

Line 340: The balance of the water in the watershed needs to be included in the discussion, by the results you can see that the distribution of rainfall during the years principally the last months of the winter that could presented issues of water scarcity, but we don’t see that the results presented.

Moderate language corrections are needed. 

Author Response

RESPONSE TO REVIEWER 4

General Comment: The manuscript presented an interesting study related to assessment of the water scarcity of livestock production in southern Brazil. The introduction is well written, presenting a good state of art. However, the methodology is very poor, the authors need to present more details about the sources of data, because in the discussion in results they are talking about data from interview and data from literature, but the authors to put a Table presenting the sources of each information presented. The sections (2.2 Input data) need to be written, for example the authors in section 2.2.2. Water Availability are talking about different scenarios however, details of those scenarios are presented in the last section 2.4 Scenario settings, the paper needs to be consistence. The authors need to presented information related the climate in region (Temperature and rainfall) to complete the information discussed.

Suggestions and Comments:

Line 133: Figure 2: the resolution needs to be improved.

A figure with a higher resolution was included in the latest version of this manuscript.

Line 148: how do the authors calculate cleaning water consumption from the literature? are you talking about the part of the cleaning water consumption?

We appreciate your comment. The daily amount of cleaning water per head of cattle (0.020 m³ head-1 day-1) estimated by the state of Rio Grande do Sul, where the watershed is located, was used to estimate the cleaning water for the total herd of dairy cattle. The sentence was improved.

Line 163: Put the Table 1 mentioned just after the paragraph where you mentioned it for the first time.

The reference to the table was removed.

Line 340: The balance of the water in the watershed needs to be included in the discussion, by the results you can see that the distribution of rainfall during the years principally the last months of the winter could presented issues of water scarcity, but we don’t see that the results presented.

As observed in the results, the water scarcity is low and even with some months with less rainfall, the negative influence of livestock on water availability is not visible in the region. Based on this and in the fact that the study year is only 12 months, we did not present the water balance.  

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I still think the literature could be upgraded. 

Reviewer 4 Report

The manuscript can be published in the present form.

Moderate language corrections are needed.