Spatial Distribution and Sustainability Implications of the Canadian Groundwater Resources under Changing Climate

Round 1

Reviewer 1 Report

This paper is a review, that explores the regional and provincial distribution of groundwater, its withdrawal, and sustainability aspects under the changing climate. The novelty is that it integrates information scattered in government reports, and scientific publications to better understand groundwater and climate change impacts on it. Specific research questions explored under the study are: what are the provincial government's interventions and regulations on groundwater management? what is estimated renewable groundwater in different provinces? and does its utilization under sustainable limits?

I recommend that this paper is accepted with major revision. A comprehensive review of Canadian groundwater availability and threats from water quality and climate change would be very useful, particularly if it includes the grey literature. However, it falls short in a few areas. Suggested improvements include:

1. More context: For a paper that is intended to be a comprehensive review, there is almost no information to provide a context for the study, e.g. a summary of the hydrogeology of Canada. Precipitation is briefly described, but not seasonality or other aspects; nor is there a summary of the trends expected under climate change. The recent trends would be better more upfront. There is no map of the provinces even though this underlies the structure of the paper. There is no discussion of land use across the country (irrigation, forestry) except for sporadic mentions. Perhaps, a summary of the regulatory conditions would be useful upfront.
2. More justification for methods of estimating groundwater availability and sustainable groundwater availability: These two quantities have been estimated by assuming the first is 20% of the precipitation and the second is 40% of that. There appears to no justification of these numbers and why they would be constant across large variations of precipitation and snowfall as a ratio of precipitation. There appear to be some areas where recharge is rejected because of permafrost, which may be changing under climate change, but no map of the area of permafrost or its trend. The description of recharge mechanisms is brief.
3. Changing the title to better reflect the paper: The title appears to emphasise the climate change aspects, but the paper is largely about spatial variations in water availability, water quality issues and climate change, with the last being an add-on. Also, the syntax appears to be incorrect.

Better linking climate change to changes in groundwater availability; There are brief comments on how climate change affect groundwater availability, but the mechanisms vary and the process linkages not well described. The climate change drivers are described on lines 69-71, but many of these are not used. Perhaps some more description of how these drivers might be expected to change groundwater availability Because of the sparsity of information, it may be difficult to provide a more complete spatial picture, but use of examples or case studies, showing the range of impacts may then be very helpful

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

The work deals with the important topic of Canadian groundwater resources. The authors presented theses and showed them in a descriptive manner. However, in my opinion, analyzed regions should be performed in the comperison form of a collective table. It would be easier to imagine for the reader. As for the substantive comments. Figure 3 is incorrect. It means that the line  and the bar graph in this case cannot be compared with each other in this way. Badly formatted range of the left axis means that we can completely misinterpret the data. The conclusion chapter also draws attention. Most of the research results are presented there instead of inferences. There is no proper conclusion of the authors and a summary of the entire work. Despite this comments, the work is interesting and noteworthy. I can recommend this work but before it is allowed to be published, it requires correction of the last chapter. 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I believe that the authors have satisfactorily responded to previous comments and I am happy for this to be published in the current form.