Dear authors,

Your paper has been reviewed by two experts. They raised many concerns with the present version of the manuscript. While both reviewers acknowledge the importance of measuring epikarst water storage with time-lapse gravity measurements, they both question to some extent the novelty of the method, as previous publications addressed this issue already before (see Jacob et al., 2009). The first reviewer also raises considerable concern on the error budget and questions whether the signal to noise ratio is appropriate in this case for analyzing epikarst water storage differences.

I carefully analyzed these referee report and your replies. Given the many concerns, the current version of the manuscript should be precluded for publication and a major revision should be made. Quite some additional information has already been submitted in your replies. This information should be integrated into the paper, to convince the reviewers about the appropriateness of the method and the validity of the results. I particularly recommend you to evaluate the possibility to expand the study period and to include data from multiple seasons. This should allow increasing the robustness and validity of the results. Of course, all other remarks need to be addressed as well.

Given the many remarks, a major revision is therefore requested and the revised version will be resubmitted to the reviewers for a second review.

Sincerely yours,

Dear authors,
Your revised mansucript HESS2016-355 has been reviewed again by one of the previous reviewers. Based on his analysis and my personal reading of the revision report, the revised paper and the new review report, I propose accepting the publication, subjected to additional minor revisions that will be reviewed by myself. In this additional minor revision, I expect that the many minor problems/ spelling and grammar errors will be solved. Please use the annoted manuscript as a basis for this additional minor revision.
Sincerely yours,

Dear,
Thanks for considering the many small spelling and grammar errors. Still, there is a technical issues that needs to be solved. Following the request of the anonymous reviewer, you included a new Figure 1 (the topographical map). Yet, this map should be introduced in the main body of the paper (E.g. at line 105. "In this study, measurements are reported for 3 sites in Southern France. The topographical situation of the study sites is shown in Figure 1"). Subsequently you need of course to change all the numbers of the remaining figures (which has not been done).
Succes with further revisions.