The manuscript “Projection of future glacier and runoff change in Himalayan headwater Beas basin by using a coupled glacier and hydrological model" was reviewed by 2 experts in the field of climate change impacts on hydrology, whilst A. Sharma contributed with an independent review to the open discussion. I would firstly like to thank them all for their feedback. This investigation is within the score of the Special Issue “The changing water cycle of the Into-Gangetic Plain”, and the manuscript will after major revisions sufficiently contribute in the scientific field.

There are a number of concerns from the referees, and myself after a personal review, which I am happy that the authors recognised and accepted for revision. Although one referee rejected the manuscript, I believe that after revisions (major considering the numerical runs that are requested) all of his/her dilemma would be sufficiently addressed. I am therefore, accepting the manuscript to proceed for a potential publication in HESS, given that all referee comments are addressed, based on the authors’ responses.

As mentioned earlier, I am pleased with the authors’ response to the referees, but I would like to highlight the following items. It is very important that you state (usually in the last paragraph of the Introduction) the scientific questions that you are answering, highlighting the motives for this investigation. I believe that the three questions which are stated in the Response to Referee #2 are of key importance in the hydrological science.

In addition, it is very important that more GCMs are introduced in the analysis, and that the authors analyse the uncertainty partition of hydrological projections from GCMs and statistical downscaling methods. In a recent special issue dedicated to results of the ISI-MIP project, a number of articles (i.e. Pechlivanidis et al., 2017; Samaniego et al., 2017; Vetter et al., 2017) analysed the uncertainties related to GCMs, downscaling and impact models. I would encourage you to proceed and also to discuss/compare conclusions with the existing literature in the Discussion session.

Finally, I am glad to read that the authors accepted to re-run the impact model with a fine spatial (3x3 km) resolution, since this has been requested by 2 referees.

Looking forward to a much improved manuscript.

Best regards,
Ilias Pechlivanidis

References

Pechlivanidis, I. G., B. Arheimer, C. Donnelly, Y. Hundecha, S. Huang, V. Aich, L. Samaniego, S. Eisner, and P. Shi (2017), Analysis of hydrological extremes at different hydro-climatic regimes under present and future conditions, Clim. Change, 141(3), 467–481, doi:10.1007/s10584-016-1723-0.

Samaniego, L. et al. (2017), Propagation of forcing and model uncertainty into hydrological drought characteristics in a multi-model century-long experiment in continental river basins, Clim. Change, 141(3), 435–449, doi:10.1007/s10584-016-1778-y.

Vetter, T. et al. (2017), Evaluation of sources of uncertainty in projected hydrological changes under climate change in 12 large-scale river basins, Clim. Change, 141(3), 419–433, doi:10.1007/s10584-016-1794-y.

This article was reviewed by two new referees. This was required, discussed and agreed with the authors, given the major work that was conducted and the changes in the list of authors. However, I am pleased to read by the referees that the authors managed successfully to address major comments. The referees and I would like to highlight the significant effort to improve the analyses resulting to a much improved manuscript.

However, I would like to stress three points, which should be fully addressed together with the minor comments from the referees, in order to consider the manuscript for publication:

1) The manuscript is very long, and could be shortened. Particularly the Introduction is very extended (3 pages) which is apparently not necessary, since the reader is interested on key messages from existing literature. Although the Discussion is adequate, I still believe that there are parts which are repetitive. Please go through the manuscript and focus on conveying simple but key and concrete messages.

2) The results and text is much focused on the climatological variables. This is fine since climatological variables drive the hydrological response, however the title directs towards a more hydrological investigation. I would therefore suggest reducing some repetitive text from the climatological analysis.

3) It is crucial that a native English speaker revise the manuscript prior to resubmission. This is highlighted by the referees also in order to improve readability.

I would like once again to thank the authors for this effort.

Best wishes,
Ilias Pechlivanidis

Dear authors,

This article was under minor revision with a review by editor only. I am very pleased to see that you have successfully addressed all minor issues pointed by the Referees and myself. You indeed improved the structure of the manuscript and language. The manuscript is now in a level acceptable for publication. I would like to thank you for your hard work on addressing the various major/minor comments from all referees during the reviewing stages and conducting significant amount of extra simulations.

Best regards,
Ilias Pechlivanidis