Dear authors,

thank your for incorporating all the revisions asked for by the reviewers. I invited a second round of reviews and copy them below. The paper is accepted for publication subject to minor revisions. In particular, please carefully consider the comment by rev.2 on the sensitivity analysis and improve the paper accordingly.

Regards,
Olaf


Rev. 1

First af all, the authors answered to all the comments made by the reviewers. I thank them.
They reformulated many paragraphs of the paper. In particular, the sensitivity analysis is now much clearer.
Moreover, they added a discussion about the validity of the assumptions made to apply their methodology.

That is the reason why, to my mind, this paper is now acceptable.

I have only some minor remarks:

- line 31: firm instead of firn?

- line 77: Jougnot et al. 2012 does not appear in the reference list

- line 114: longitudinal (i.e., in the direction of the slope) instead of lateral?

- line 242: Albert et al. 1998 does not appear in the reference list

- line 293 (equation 8): define what is the pzc (isoelectric point)

- line 519: Jouniaux et al. 2009 does not appear in the text

- line 537: the year (2007) is missing

- line 589 (Table 1): since the uncertainty range is deduced from the sensitivity range, maybe place the sensitivity column before the uncertainty column

- line 594 (caption of Figure 1): say somewhere the size of the SP grid (in order to have a scale)


Rev. 2

The authors have done a nice job revising this manuscript. Overall, it is much improved, and the new conclusions section helps pulls the manuscript together. It should be published, addressing a few minor last issues.

The results of the sensitivity analysis are interesting. In particular, the authors note: “Despite our consideration of extreme potential error bounds, calculated uncertainties in liquid water contents are restricted to a relatively small range (~ 20 % for large assumed uncertainty in the zeta potential, and ~ 3 – 4 % otherwise)”—if this is the case, then the downside of such “robustness” might be: who needs a measurement? Could we not just guess a field value and do a calculation and be close to the truth? I suppose the variation in impacts associated with the zeta potential would be the crux as noted in the conclusions, but perhaps the other result is just that the rest of our measurements aren’t important. Do I misunderstand? I feel like this part of the paper still isn't as clear as it could be.

I’m also not sure how to place a reference electrode where no streaming potential exists. How do you find this place? I appreciate that it is “elaborate” but some elaboration would be useful to the readers of this paper.

Because the conclusions section is wholly new, I have a few comments/questions:
Line 441: the authors talk about the “scaling factor”—it would be good to note what that is again here.

Line 461: “overestimation of pore diameter” — citation needed.

Line 463: Re = 50.7—is this really good to three significant figures?

Line 474: Was there an inversion here that I missed? It seems like there are just basic calculations done on raw data—did I miss something fundamental here?

Dear authors,

thank you for providing a revised version of the MS ans responding to the reviewers' comments. I am happy to accept you MS for publication, with few recommended changes:
l25: and Rhone -> at Rhone
l31: hydrological -> hydrology
Please also make sure that your MS conforms TC's editorial style w.r.t. equations, variables, etc.
Regards,
Olaf