Establishing Stage–Discharge Rating Curves in Developing Countries: Lake Tana Basin, Ethiopia

Round 1

Reviewer 1 Report

Dear Authors, Thank you again for your submission, however it is not clear to me the updates made in the revised except the minor change from research article to communication article. From my point of view this work is not a communication article which by definition is the type article for providing preliminary results of an experiment. The type could be only case study as an article. There is a lack of scientific novelty in this article even we refer to a data scarce area. I summarize my following flaws: 1. Lack of hydraulic calibration in the site of stage discharge development 2. Not detailed discussion/evidence for quantifying the uncertainty in the new stage discharge equations. The paper in its current format is not a scientific paper. I leave the final decision with the Editors given the scope of the Special Issue. I would recommend rejection, however look at the scope of the SI my recommendation is major revision. I would appreciate if the next submission will follow a total different approach.

Author Response

DEar Reviewer

Thank you for your comments.  The manuscript with tracked changes is attached.

Regards

Tammo

Author Response File: Author Response.pdf

Reviewer 2 Report

Interesting manuscript to read. The manuscript in general was written well. However, I have few issues to clarify. In addition, some comment are there to improve the quality of the manuscript.

1. Abstract - Better to strengthen the abstract from findings in real world. Not mathematically but in the sense of engineering.
2. Introduction - Surely have to be improved. Enhance the research gap and showcase the importance of your research work to the localized stakeholders.
3. Materials and Methods - The subsection title "Theory" is unsuitable
4. Figure 1 - Can you use a contrasting colour to show the gauges?
5. What is the resolution of the data? Daily, hourly ? I mean flow measurements using current meter?
6. Is there any changes of the instrument for measurements? I guess, there is,. How did you work on such cases? I know you have removed the outliers; however, it would be better to mention the reasons?
7. Figure 4 - Colour in Red?
8. Results and discussion - I am not sure if Figure 4 can be results of your work, rather they are observations by done someone else?
9. Table 2 has to be explained in detail
10. I like results and discussion to be in one section. You can easily fix the comment 9 if you do so?
11. Excellent R² values; what are your suggestions on these in practical world?
12. Conclusion - Conclusion(s?)
13. This is not conclusions just a summary and same text as Abstract? At least few sentences? I want you to write the Conclusions from the results.
14. Turnitin scores are at 10%. This is good.

Author Response

Dear Reviewer,

Thank you for reading and commenting on the manuscript.  The comments our responses and the original manuscript with tracked changes are attached.

Best regards

Tammo

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I'm happy with the comments addressed. Therefore, this can be moved to publication.

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

The paper “Establishing stage-discharge rating curves in developing countries: Lake Tana basin, Ethiopia” is interesting and fits the scope of the Hydrology. The paper presents a study that promises direct usability, which greatly increases the value of the results.

However, I thought I had important shortcomings in terms of scientific foundations and backgrounds.

The manuscript did not show why and under what conditions the basic equation (Equation 1) can be applied. Why is it assumed that Equation 1 is applicable to all cases examined? Show the derivation of the equation and what the applicability limits are. For example, the equation was derived for a steady-state (based on the Chézy formula). That is, it is not applicable in the case of high-gradient flood waves. But more importantly, above the bankfull stage (if the floodplain is flooded), the curve will change. Was this taken into account in the investigation?

 

The rest of the study is understandable and logically structured. I suggest improving the quality of the illustrations!

Reviewer 2 Report

The paper presents a flow rating curve analysis in a gauge data scarce area in Lake Tana, Africa. Even though there is a strong need to provide robust methodologies in data scarce areas, the paper in its current, fails to provide a scientific justification along with a proper scientific value and seems as being a case study technical report. I would recommend to find a suitable scientific journal for new submission.

Reviewer 3 Report

This submitted article addresses the important issue of building rating (RC) curves and assessing their uncertainty, especially when rating shifts are induced by morphological changes due to floods. The authors suggest a unique stage-discharge curves in which the discharge was expressed as a function of the water level and a time-dependent offset from zero. In addition, the offset was expressed as polynomial functions (up to order 4) of time. In my opinion, the methods proposed in the paper are questionable and the reported validation is far too weak for convincing the reader that they are reliable. Therefore, I do not think that the paper is suitable for publication in Hydrology journal. Hereafter are some specific comments explaining why I think that the suggested approach do not present neither theoretical novelty nor practical interest.

                                                                                               

The use of equation 1 for designing RC is usual in hydrometry. However in practice, different instances of Eq.1 must be applied to separate segments of the RC, because hydraulic controls are not the same for low flow conditions (usually controlled by a natural or artificial weir) and medium or high flow conditions (usually controlled by the main channel and floodplain geometry and roughness). This explains why rating shifts are more important at low flow (see Fig.5) while all RC converge to the same line at high flow. Another severe comment is to ignore all the recent work on the uncertainty of the rating curve and its impact on the analysis of the flood frequency (4, 5) and in the improvement of the accuracy of the predictions of the rain-gauging model (3, 2)