The manuscript presents a hydrological modeling study in a glacier-influenced catchment. The work explores the value of auxiliary datasets, namely water isotope composition, snow cover area, and glacier mass balance in model calibration in a GLUE framework. The model structure allows tracer simulations and comparison with spatially variable datasets. The works finds different datasets have more power in model calibration in different hydrological seasons: isotopes during baseflow, and snow and glacier related observations during the melt period.

I liked the systematic approach for including model validation datasets of very different origin to model evaluation scheme. The GLUE uncertainty analysis framework for the work is in my judgement valid. The overall approach the authors develop to explore parameter sensitivity to model validation objectives and stream source water contribution are in my opinion of interest to the community. I recommend the work to be published after addressing my comments below:

MAJOR COMMENTS

I’d like to see better presentation of the stable water isotope data. You have only isotope data of the streamflow validation, it remains unclear how representative the input precipitation data is of the catchment. Do any of the references cited for the model development have any comparison data for simulated precipitation, snow or groundwater isotope composition? Having even cursory validation of the simulated isotope composition in different model compartments (snow, glacial melt, groundwater mainly) in the would give more credibility that the streamflow isotopes are correctly simulated and informative for the right reasons. On that note, I’d like to see a figure of the stream isotope data and model simulation fit to stream isotopes.

The fractions for snowmelt surface runoff and glacier surface runoff seem low to me. Can you provide comparison with fractions found in other montanous snow and glacier influenced sites? Quite often end-member mixing analysis fraction estimations are done for three end members: snow, rain and glacial melt. In your model analysis groundwater is explicitly considered as a component, but isotopically it is essentially composed of rain, snow and glacial melt. This in my opinion creates a bit of confusion, and makes the glacial and snow melt seem less important for the regions water resources. I don’t think there is an error in your analysis, but would be good to clarify the concepts further, to make your results more relatable to other literature.

MINOR COMMENTS

L12: I perceive GW-SW interactions as specific water exchange processes between surface and subsurface water. As you don’t really delve deeper into GW-SW interactions in your simulations, I’d propose that you stick with talking only about baseflow, not GW-SW interactions (which baseflow generation if of course a manifestation of)

L54-L66: seems like the research questions are to some extent repeated. Suggest to review and rewrite more concisely.

L110: Do you think snow sublimation would be a significant flux in your region, possibly influencing the snow storage and isotope composition of the snowpack consequently snow melt?

L213: not clear how the simulations comprising the pareto front (red markers in  are selected. seems like the number of the included simulations is fairly low, around 15.

L238: can you further explain where the prior parameter distributions in Fig.4 comes from. Is it the parameters with >0 NSE for streamflow?

L304: I don’t fully understand why the sensitive LL parameter does not manifest in the snowmelt fraction.

L307: the narrower ranges for isotope simulations are not evident visually compared to the Q simulations. Would any statistical test either looking for differences in central values or variability in the distributions be helpful in identifying the differences?

L310: incomplete sentence?

L341-343: not very clear how successful the snow cover extent simulations are in the first place. The NSE metric is not very intuitive for snow cover extent variable. If for example the extent in area does not quantify, if the snow cover is simulated in the correct location. Similarly as requested for the isotopes, can you provide the timeseries of observed vs simulated snow cover extent to identify and discuss some potential some biases.

Please kindly find my review on this manuscript in the attachment.