|Widespread and increasing violations of environmental flow envelopes|
Since the last revision, the authors have answered and addressed the most important comments of the reviewers. Especially the inclusion of pre-industrial violation results and the omission of overly strong language has markedly improved the manuscript.
However, there is still need for further clarification and specification in some aspects of the abstract and discussion. By improving these sections this study could be presented more robust. Moreover, there is also an opportunity to improve the writing. Therefore, I recommend minor revisions.
Note that some of the comments to do with the writing are based on my personal writing experience, and are not “wrong”. However, they may help the authors to improve their writing throughout the document.
Line 28: What uncertainty? Please clarify
Line 29: “The sub-basin specific EFE is” to “Sub-basin specific EFEs are”
Line 30: “and its derivation considers the methodological uncertainties”, again please clarify
Line 32: Maybe mention Q95 here?
Line 32: “This” to “This upper bound”
Line 33: “Long-term” is used throughout the manuscript, for different meanings. This is sometimes confusing. See also some comments below. “Long-term” to “annual”?
Line 37: Best to move “global hydrological model outputs from the ISIMIP2b ensemble” to its own sentence (perhaps at the start of the paragraph “Discharge was derived from ...”).
Line 40: “widespread, occurring” to “widespread and occurring”, as one refers to the spatial extent and the other the temporal extent.
Line 44: “spatially distributed” to “dispersed” as in the discussion.
Line 46: Ending on a positive note would be stronger, what is the broader application of your study?
Line 54: “population growth”, not only growth but also agricultural and population development (irrigation expansion and diet changes).
Line 63: Probably remove “in addition” as it specifies, and not adds to, the previous sentence?
Line 124: What are “mechanistic equations”? Probably use “process-based”?
Figure 1: Could the three month threshold be included here?
Line 165: What do these levels mean? Maybe omit?
Line 200: Normal distribution cannot be assumed for discharge. I did a quick test for 100 of the world’s largest rivers, and normality could only be assumed for half of them (using the Shapiro-Wilk test on multi-year average measured discharge). Moreover, why is it assumed there are errorous outliers in model simulations that should be removed, how do simulations make errors? This also affects the Q95 upper bound in the study. If so, this should be discussed.
Line 328: “figures” to “values” or “results”.
Line 423: “both long-term and recent”. “Long-term” here is referring to “more than three consecutive months”. However, as long-term is used in combination with “recent”, which refers to the last 30 years, which is confusing. As an alternative to using “long-term” I would propose to use “extended” or “persisted” throughout the manuscript?
Line 425: If possible, could the absolute values be included in the supplementary?
Line 434: What is a possible reason for this wider spread? Is it related to the model ensemble?
Line 437: Can you expand upon these limitation (perhaps with citations)? Or maybe move this to section 4.3, where these limitations are discussed.
Line 441: “(i.e. not taking potential climate change impacts into account as we do)” would be better at the end of the sentence, were you discuss what your study does. “(...) which is different from our seasonal analysis based on the pre-industrial period and includes potential climate-change impacts”
Line 451: “cautious interpretation of our results” to “cautious interpretation of our results in these regions”
Line 465: Would omit this sentence as it is discussed before and is addressed in the results.
Line 491: Although the limitations of EFs are described, could you indicate how they are useful? Currently this section seems to undermine the value of your study.
Line 509: Important for what? Please elaborate.
Line 513: Why this specific number? Maybe just omit?
Line 507: “On the one hand (...) but on the other hand”. These sentences do not contradict, just use “and”.
Line 508: Is there also an advantage to the spatial aggregation (as there is for the temporal aggregation)? If so it would be good to mention here.
Line 521: Could you elaborate on why the separation of natural and anthropogenic flow alterations would give additional information on the “seriousness” of major violations?
Line 530: “On one hand (...) On the other hand”. These sentences do not seem to contradict. Maybe use “nevertheless” instead of “on the other hand” (and omit “on the one hand”).