Seasonal and Annual Rainfall Variability and Their Impact on Rural Water Supply Services in the Wami River Basin, Tanzania

Round 1

Reviewer 1 Report

The manuscript by Twisa and Buchroithner (2019) presents an interesting and important study on connection between rainfall and water service in a river basin, Africa. Water quality and supply is very important for humans and livestock. From my perspective, one important and new contribution of the current study is its combination of widely used rainfall trend and variation analysis, and survey-based water service information. I think the manuscript is worth to be considered for publication. Please find my detailed remarks below.

 

Section 2.2 should be Methods and Data. Regarding the data used in current study, could you please add data link and quality information into the manuscript. It is important to keep it reproducibility. And the quality of the rainfall data has strong impacts on the analysis conducted afterwards. Please add specific locations of Kongwa, Dakawa, and Mandera stations in figure 1.

 

The captions of figures need to be revised to add necessary information. For example, figure 3, the y axis needs to be explained. What is OND, MAM etc.

 

Regarding the quality of survey data, how do you control the quality? What is the influence of its uncertainty on the relation between rainfall and water service?

 

I think it is also interesting to add some discussion on the potential of predicting future water service based on modeled rainfall in the future, based on your findings here.

Author Response

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Reviewer 2 Report

This study appears to analyze the impact of changes in rainfall patterns on rural water supply services by analyzing trends using rainfall data from the last 35 years in Tanzania. In particular, this study not only analyzed trends using annual rainfall, but also conducted seasonal trends. Therefore, this study is intended to examine the change of rainfall pattern for water supply in more detail. However, the results of the trend analysis and seasonal variation presented in this paper are not sufficient to predict the impact of rainfall on rural water supply services It is also likely to give inaccurate results because other variables have a greater effect on estimating the change in water quality using rainfall data only. It seems that there is a lack of research novelty that can be obtained from the paper. I think you need to emphasize the research part of the paper more. Also, if you supplement the paper with reference to the contents below, I think it can be a better paper. It is not clear from the figure that Figure 5 ~ 9 want to show. It is inaccurate to get information from the picture. You need to express it in a different way. Wet season and dry season should be indicated in Figures 5, 7, and 9. Proof-reading of the entire article by native English speakers is strongly recommended.

Author Response

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Round 2

Reviewer 1 Report

I do not have further comments on the manuscript. Please double check the language and finalize the manuscript.

Author Response

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Reviewer 2 Report

It seems to have been corrected to reflect the first review. English readability has improved.

As this paper examines the water supply and demand and seasonal patterns in Africa, it is expected that it can be used as a basis for the planning of future water supply priorities and priority periods.

In particular, Table 3 are considered useful data to examine the current state of water supply in the region.

But still some modifications are needed.

Wet season and dry season should be indicated in Figures 5, 7, and 9.

Author Response

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This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This manuscript analyzed the seasonal and annual rainfall variability and their impact on rural water supply services in Wami River Basin, which is in conformity with the scope of Water and of practical significance. I recommend it publication in Water after the following minor revision is completed.

 

Specific comments

1) In the section “Introduction”, please add more research progresses concerning the seasonal and annual rainfall variability in Wami River Basin.

 

2) In the subsection “Methods”, please make a concise description of the frequently used methods Mann-Kendal Test and Petit Change Point Test.

 

3) If possible, please add some interpretations of the mechanisms on the spatial distribution of changes in water points quantity and quality from wet and dry seasons, respectively.

 

4) For Figures 2 and 3, please use straight lines to plot the corresponding time series, not the curve lines.

 

5) The English language is needed to be improved by professional agencies.

Author Response

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Reviewer 2 Report

Overall comments: The article has wonderful visuals of the water point and spatial data contained within the article that provide the reader with a full sense of the area the research was conducted in and the layout of water points and precipitation measurement stations. However, the overall contribution of the article is unclear. The argument seems to be that rural water points are significantly impacted by seasonal variations in precipitation; however, the author notes that there is already a robust set of research that demonstrates this same finding, and it is a finding that would seem rather intuitive on its face anyways (not that this means that it should not be investigated). The author would do better to make very clear the contribution of this work and its novelty relative to the other works it cites. Is the approach taken here different? Is this approach more effective or efficient in any way? Or, could it be that the geographical region is under studied and therefore this is filling a regional gap? Also, the author would do well to discuss the limitations of using monthly precipitation data rather than weekly or daily. Flood events, where much surface runoff is lost, happen in days not months, so how might accounting for months miss out on the flashiness of these events? If you aggregated your data to months but have it at a daily or weekly level, I highly recommend disaggregating and reanalyzing. In total, this article has a lot of data included that could be really useful, but how it is currently packaged needs refinement to really hone in on the argument being made and the contribution of the work. Directed comments are below.

 

Direct comments:

-Line 30-31: “The significant challenges posed by climate change are records of trends in rainfall and their effects on river flow to assist in water resources management.” Are you saying that this is the only significant challenge or the most significant challenge? Either way, you need to qualify this and probably support it with more evidence than the single reference given that this statement is likely to be rejected by many readers.

-Line 32: “According to the IPCC (Intergovernmental Panel on Climate Change)” This is the second time you have used IPCC, need to explain the acronym at first use.

-Revise wording lines 41-42, improper syntax.

-For the paragraph contained in lines 49-55, are you saying these generalized trends are for all water systems, meaning rural, urban, etc.? If so, please specify and then connect to your individual paper somehow. As it stands, seems to be just a set of general statements with no real direction.

-Line 64-65: Predicted by who? Is this your prediction? If so, specify. The whole paragraph might use a bit of tailoring as you are making very generalized statements about an entire continent, but your case study is a very specific area: why not focus more on the area you are going to be working in so as to present more high resolution facts in this section?

-Line 83: How can the mean annual temperature vary between 12 to 24 degrees, unless you are stating this as a confidence interval (if so, at what level of confidence?)? And what years are you sampling to provide this value?

-Line 89: syntax error, revise.

-Line 102-103: syntax error, revise.

-Line 102-112: A generalist audience (i.e. one not trained in advanced statistics) will have difficulty understanding the procedure you have conducted. Recommend revising to be more easily understood.

-Line 119: What is the “tie”?

-Line 145-156: When was the data collected? How many interviews collected? You mention 60 questionnaires, what is the estimated total population size that the sampled 60 are a part of?

-Line 163-164: syntax error, revise.

-For Figure 2, why are you reporting the R2 value? If you are not using date to predict rainfall amount, and therefore just using the regression line to show the overall trend in rainfall, then the R2 has no useful interpretation and only confuses the reader by being included.

-Line 183: citation and syntax error, revise.

-Line 184: The logic of your argument does not make sense, I think there is something missing in your explanation. Also, sustainability means a lot of different things to different people, highly suggest defining what you mean when you use it here.

-Line 188: syntax error, revise.

-Line 189-190: Your math doesn’t compute. You say more than 67% do not function and 33% do function, which together equal 100%. So how can more than 67% not function? Is it not exactly 67%?

-Line 191: You say a large number change. You have the data, why not report the actual number that change from functioning to non-functioning?

-Table 1: Need to define variables such as “good”, “poor”, etc. What are the parameters of these descriptors?

-Lines 227-228: syntax error, revise.

-Line 230-232: Again, report the actual number, you have the data.

-Line 242-243: You say that a robust set of previous research has demonstrated the exact argument that you are trying to make. So then what is novel about your research then? What does this study tell us that others do not, or how is your approach different or more useful (therefore making this a methods paper potentially)?

-Line 249: syntax error, revise.

-Line 254-255: syntax error, revise.

-Line 255: What “conversion” are you talking about?

-Line 281-282: syntax error, revise.

-Line 292-293: syntax error, revise.

-Conclusion section: The conclusion section summarizes many of the statements previously made in the manuscript, but then it also includes many extension statements (connecting to ideas outside of the main thrust of the manuscript’s argument) that are not developed in the paper and seem misplaced. Recommend revising to focus on the specific contribution of your research and approach relative to the other research on this topic, and then also connecting it to specific policy or management recommendations for the Tanzanian government entities that are involved in rural water provision.

Author Response

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Reviewer 3 Report

See the attached document.

Comments for author File: Comments.pdf

Author Response

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Round 2

Reviewer 2 Report

There are still many issues with the manuscript. In the first paragraph alone there are several nonsensical statements and syntax errors. For example:

-Line 13-14: "Rainfall is subject to increase resulting in widespread droughts and floods..."

-Line 15-16: "The present study analyses the trends in annual..."

In the first example, how is rainfall subject to increase? And this is somehow associated with drought and flood? In the second example, the correct word is analyzes--singular--not its plural form, analyses. I include only these two examples but there are many throughout the manuscript that make it difficult to follow and understand.

There are also several instances where the statement made does not match the reference paired with it. For example:

-Line 45-46: "Rainfall is the most critical meteorological phenomenon for natural ecosystems and human life on Earth, characterizing it as the most critical ecological factor [12]."

The reference cited is about a local level study in Kenya of rainfall, not a earth systems study that demonstrates that rainfall is, in fact, the most critical meteorological phenomenon. Improper citations lead to questions about the credibility and efficacy of the article.

While many changes were made to the manuscript, much work remains.

Author Response

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Reviewer 3 Report

The manuscript has been well improved. I congratulate the authors. The results make it possible to have a good knowledge of the state of the water resource of the studied basin, and of its evolution (quantity, quality). The methodology developed in this work should be extended to other basins.

Author Response

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Round 3

Reviewer 2 Report

N/a