Dear Authors, dear Referees,
I find the paper clear and certainly of broad international interest, the methods are correctly and soundly applied and the Authors indicated, in the lively and fruitful discussion, that they are willing and able to address all the important and constructive points raised by the Referees (whom I deeply thank for their precious input).

I believe that the importance of all the potential case studies, that is not only the specific Kavango River study basin, but all the understudied and poorly gauged catchments that may be studied with this kind of approach and open data and models provides a good motivation for the publication in HESS even if, as correctly highlighted by referees 1 and 3, scientific novelty is not the main feature of the paper.
Such motivation is particularly sustained in the most recent “guidelines” provided for the journal, given that at the last Fall EGU Publication Committee, it was proposed to add a new type of manuscript type, devoted to the description of (citing from a first draft elaborated by the Committee) “interesting and novel case studies that broaden the knowledge base in hydrology and share the underlying data and models structures” and I strongly believe that the wide interest that the adequate use of open data and open models has for all the hydrologists that attempt to study catchments located all over the world but in particular in developing countries and/or at large regional scale, may fully justify the publication of the manuscript, following a careful revision according to the Referees’ suggestions.

In addition to the points raised by the Referees, I would also suggest to add more information on the main features of the study basin (area, elevation, …, for both the basin closed at Mohembo and the subbasin at Rundu) and also on its location in the region (widening the map shown in Fig. 1). In addition, I would move from section 2.4 to section 2.1 the description of the hydrometric measures and I would also add some details on the calibration and validation periods (are they statistically similar? do they include a variety of hydrological situations? etc). Please add the equation describing the ME used as part of the objective function.

I look forward to getting the revised version of the work.

Best regards,
Elena Toth
HESS Editor

Dear Authors,
thank you indeed for your careful review, where you adequately address all the comments raised by the Referees and myself.

I sent the revised version to one of the previous referees, who acknowledges that you satisfyingly modified the paper according to the suggestions; he/she still have doubts on the opportunity to publish this kind of work on HESS, but, as I have already written in my comments in December, I believe that the wide interest that the adequate use of open data and open models has for all the hydrologists that attempt to study catchments located all over the world but in particular in developing countries and/or at large regional scale, may fully justify the publication of the manuscript.

I would ask you to answer to the last three points raised by the Referee and submit a second revision (that I will revise myself).

My best regards,
Elena Toth

HESS Editor

Dear Authors,
thank you for this last effort.
I look forward to seeing your paper published in HESS.
My best regards,
Elena