Dear authors,

Thank you very much for submitting your responses to reviewer comments. Your original manuscript received two appraisals which were generally in agreement that your work could make a valuable contribution to the existing literature on the underlying processes that control soil water isotope ratio variations. However, they did highlight some areas where more clarification on methodology and assumptions was needed and concepts needed better explained.

I agree with these evaluations and invite you to revise your original manuscript following your planned changes as outlined in your response, with specific attention to the model and proposed mechanisms of mixing. While it is indirectly addressed, it would be good to recognise specifically that the direction of shifts in isotope values are seldom exclusive to specific origins and processes but rather the product of a combination of source variation, mixing and fractionation effects; i.e. a direction of shift in isotope values consistent with a process does not provide direct evidence that other processes did not occur or were not important. I would also strongly encourage you, as you suggest, to include the conceptual box model to illustrate the processes and support the mixing equations. Finally, where you outline suggestions for future developments, I suggest this also includes a consideration of the applicability of your proof of concept to undisturbed soils.

I look forward to receiving your revised manuscript after these relatively minor edits.

Best Regards,
Josie Geris

Dear authors,

Thanks for submitting this revised version of your manuscript. You have thoroughly addressed those areas where clarification on methodology and assumptions were needed and concepts needed better explained. The revised figures have also added more clarity. I would just like to point out two small things:

L47-50 doesn't read well. Do I understand correctly that there seems to be an 'and' missing?

In your terminology related to the two soil water pools as defined in this study, you make a distinction between gravity drained water and matrix water. In the definition of matrix water you refer to accessibility of that water to plants, but for gravity drained water you do not. I recognise you may have intended to link this to the explanation of ecohydrological separation/the two water worlds, but for consistency and clarity I would recommend you do/don't include reference to plant accessibility for both. Whether or not this water is accessed by plants provides context but is not addressed in this study, and recent research findings elsewhere have suggested plant water use from either soil pools, depending on local hydroclimatological conditions.

I look forward to seeing the final version published in our special issue.

Kind Regards,
Josie