The reviewers provided very detailed reports: in some cases, their arguments are very accurate and far-reaching. I think the authors should profit from this opportunity to deeply revise the manuscript, in order to focus several aspects in a better way.
I notice that two of the reviewers raised concerns about the use of random fields, which share the same statistical structure, with different ranges of K values, but without a strong variation in the hydrogeological structure between the two test cases. I recommend the authors to deeply reconsider this question, which - by the way - somehow interacts with the comments about scaling from reviewer #2. The answer proposed in the reply to reviewer #3's comments (“Furthermore, it would be intriguing to undertake a comparative analysis of various hydrogeological conditions to gain a comprehensive understanding of the efficacy of inverse methods.”) is too generic and not fully satisfactory, in my opinion.

Both reviewers suggest to publish the paper in its present form.