Dear Authors, thank you for providing a detailed response on how the comments of the two anonymous reviewers that kindly agreed to review the manuscript have been addressed. That is appreciated. However, the responses submitted also left me somewhat confused. It would appear to me that the main comments provided by the reviewers in their report have not been addressed, and that you have rather focused on the detailed comments, which both authors provided through the annotated PDF. The reviewers did also make some very substantial comments. Perhaps you have accidentally overlooked these as these were in the first part of the report and not the attached PDF. To proceed it is important that these comments are addressed as several of the points raised will need careful consideration and also substantial review. For convenience I have copied the comments from each reviewer below. Please provide a detailed response to these main comments. It would also be appreciated if for these as well as the comments already addressed more clarity on how the text has been amended to address the comment. Please provide line numbers where applicable (referring to those either in the original or in the amended manuscript). At this stage of the review process, I am following the recommendation of the reviewers to substantially revise the manuscript, after which I will again seek the opinion of at least 2 anonymous reviewers. I do believe that following this decision the amended manuscript will need to be submitted. Please provide a clear track changes version, as well as a clear outline/report of how all comments have been addressed, both the main comments, as well as the minor comments raised in the PDF.

Kind regards,
Micha Werner, handling editor


Comments made by Reviewer #1
The paper addresses a practical and regionally important issue within the broader context of water resource management—evaluating the performance of remote sensing-based evapotranspiration (ETa) models in an irrigation scheme in South Africa. While not breaking ground scientifically, the work does offer new observational data from a lysimeter, contributing valuable empirical input to the ongoing validation of satellite-based models. The authors have appropriately credited existing literature and positioned their work as an application-oriented assessment, potentially beneficial for operational water management in similar semi-arid agricultural regions. However, the contribution to Hydrology and Earth System Sciences is limited to new data and validation.

Despite its practical relevance, the paper falls short in several critical areas of scientific rigor. The methodology is not sufficiently detailed to allow reproducibility, particularly regarding the extrapolation of lysimeter data to broader spatial scales using NDVI and weather station data. This key step lacks clarity and justification. Moreover, the use of a single small-scale lysimeter (0.07 m², barley crop) to validate models over a large and diverse 36,000-hectare scheme is problematic and undermines the reliability of the conclusions. The paper fails to account for variability in crop types and their respective Kc-NDVI relationships, resulting in questionable generalizations. Furthermore, the presentation suffers from unclear language, missing supplementary figures, and a title and abstract that do not accurately reflect the study’s scope or limitations.

To meet the scientific and editorial standards of Hydrology and Earth System Sciences (HESS), the authors must significantly improve the methodological transparency and analytical rigor.

- They need to clearly explain how lysimeter-derived ETa was extrapolated across different crops and locations, addressing the variability in NDVI-Kc relationships.
- Quantitative uncertainty analysis, considering extrapolation and measurement errors, should be introduced to evaluate the sensitivity of results and robustness of conclusions.
- The title and abstract must be revised to better represent the geographic and methodological scope.
- Missing supplementary materials should be included, and the overall structure, clarity, and language of the manuscript should be refined to enhance readability and traceability.
- In addition, all the specific comments must also be addressed (see my comments in the attached PDF). If you have problems seeing the comments, let me know.

Comments made by Reviewer #2
The manuscript evaluated the performance of remote sensing-based ET models, SEBS, SEBAL, CWSI and VI-based in the Vaalharts Irrigation Scheme in South Africa.

The title says ...in arid agri environments, yet the study is in an irrigated agri system. Please revise. Also, the section titles need to be revised, they are either too long or do not relate to the subject that follows

The introduction and methodology are adequately written. A few points of clarity with the study area description:

- Can the exact location of the experimental site (where the lysimeter was installed be shown on the map (Fig 1 (a))

- what crops were planted for the duration of the research? Including at the weather station sites

Results section sequence is quite confusing to follow. There are 2 main sections we'd expect to see:

- Performance of the ETa models at the lysimeter location- and the temporal assessment. The comparison of the models is not clearly outlined outside of Fig 6 and 7. Please add description related to the figures

- Performance of the modeled against interpolated ETa at the weather station sites

Finally, the spatial distribution of the ET per model should be last in this section

Sections 3.5 and 3.6 both focus on evaluation of ETa models at weather station sites. They should not be stand alone, maybe they can be sub-sections

Minor comments on the attached document.

Dear Authors, we have received the reviews from the two reviewers. They both agree that the manuscript has substantially been improved in this second revision. However, there are still several comments that have been raised. While both reviewers consider these as minor, I do think these need to be addressed carefully in reading the reports submitted. I would therefore ask you to now provide your response to the comments raised, and indicate in those responses how you intend to further improve the manuscript,

kind regards
Micha Werner
Topical Editor.

Dear Authors, thank you for restarting the review process and submitting the revised version of the manuscript as well as the detailing of how the comments of the authors are addressed. While these seem adequately addressed to an extent, it is not easy to follow in the table where and what has been changed (e.g. line numbers), also as the track changes version appears to also include the revision from the first round. More importantly, the reviewers, in particular reviewer #1 made some comments in report which were not in the PDF. It appears that these comments were not addressed, while these were the most substantial. I will copy these reports on in the private note. Reviewer #2 raised the question on the title, as did reviewer #1. You did not respond to the suggestion made by reviewer #2, so it is now not clear to me what the title is.

What I would like to ask you to be able to reduce the confusion, is to make a more clear document responding to the comments raised by the reviewers. Start that with the general comments raised, and please copy in the full comment and then below that the response. It would be very helpful if you could also indicate the line numbers where things were changed. If possible it would be good to include the track-changes version with only the changes made in this second revision (i.e. accept all changed from the first revision). This could expedite the process for myself.

Thank you,
Micha Werner

Dear Authors, thank you for your patience and apologies for the long process in the review of this manuscript. Based on the recommendations of the two reviewers and the responses you have provided through revision of the manuscript I would like to now propose to move forwards and recommend the manuscript for publication. I have read through the manuscript to some level of detail, and bearing in mind that there is no longer a copy-editing service for manuscripts that are accepted for publication, I would like to ask to make some corrections to the manuscript prior to publication. These corrections are mainly editorial comments (ie grammatical errors), but also there is the need to improve some of the figures. I have also carefully reviewed the list of references included and found that the references do not follow a consistent format, and in many cases also do not include all the information that is required for the different reference types (e.g. journal, book chapter etc.). Please consult the very detailed submission guidelines on the preparation of the manuscript (https://www.hydrology-and-earth-system-sciences.net/submission.html). This describes how references should be formatted and what information should be provided with each type of reference. Please update the reference list, consistently following the guideline. This also provides guidelines for the mathematical notation of equations and in how these are incorporated in the text. Also here consistency is important. I have included several comments to this extent in the annotated pdf. Finally, I would recommend before submitting the final version to do ask a third person with good English skills or a professional editing service to do a thorough review. I have again made several suggestions, but these may not be exhaustive. While these are primarily technical corrections and the reviewers have commented on the scientific content, the extent of the comments I think warrant this as a minor revision, which means it will pass by me again prior to publication.

The annotated manuscript PDF with comments included in attached.

Dear Authors, thanks for addressing the minor comments and corrections to the manuscript. I have very rapidly re-read the revised manuscript and believe the comments have been addressed. For Figure 5, I would still suggest to use the 0-8 range for ETa for three of the four figures. That would already help.

Thank you and for your patience,

regards,