|Review of: Quantification of Drainable Water Storage Volumes in Both the Catchment and the River Network utilizing GRACE, River Discharge and their Phasing|
My understanding of this article is that it presents a study of a simple “cascading” bucket model that has been calibrated with GRACE data and discharge observations for the Amazon River Basin.
I think the work in the paper is mostly fine, and publishable, as it offers a somewhat novel approach to interpreting the link between storage and discharge data, and builds upon the authors previous work in a direction that contributes to this conceptual understanding of hydrology. It features the GRACE observations in the context of in situ discharge observations, which is a nice comparison to explore in more depth.
There is one major issue that bothers me a bit. The author, in response to the reviewer request, has spent three pages, 7 figures and a table describing the relationship between his work and a previously published paper by Tourian et al (2018). Yet, there is no mention of nor citation to this previous work in the actual manuscript! I think at least some brief treatment of this discussion comparing the two works needs to be included. I understand the authors desire to focus this article on his own work, but this needs to be addressed in some way, at least with a brief mention. In fact, the authors insight on this previous work would be potentially valuable to the community and is important to share.
I feel that the above-mentioned point was the most severe, but could be repaired with little effort, since much effort has already been done in the response. To that end, I would make some additional minor suggestions for changes here. If these major and minor points could be addressed sufficiently, I think the article could be publishable after another review. These points include changing the title, shortening the abstract, editing the introduction and better organizing the paper and subsections.
1) I am worried that the title of the article is not the best descriptor of the work contained therein. I would like to see some explicit mention of the “application to the Amazon basin” in the title, as well as the phrase “conceptual model” or “cascading storage” model or “ cascading bucket model”. These phrases represent the most exciting aspects of the work, and would help to more clearly and explicitly identify the work contained in the manuscript for the readers, as mentioned by the previous reviewer.
2) I would also ask to remove the term quantification of "drainable water storage” from the title, as that point and the associated results do not seem to be the primary focus of the work in the article. This exact phrase was used for the first time in the hydrological literature by Tourian et al (2018, WRR). It seems there may be too many concepts in the title (e.g. “phasing”). The importance of the "drainable water storage" is not sufficiently highlighted in the introductory and background text, and I feel it is a distraction for the audience and not loyal to the focus of the work presented through the manuscript. This term and the associated results can be mentioned in the abstract and main text of course, where they can properly be placed in the context of previous studies on this topic. But it feels a bit distracting in the title.
3) the abstract is probably too long, and could cut 4 or 5 sentences, and remove the citation.
4) The first two paragraphs on “extractable water resources” are misleading and out of context – this paper never presents work on the extractable water resources, and should clearly mention that. The work eventually presented on drainable water volume is a theoretical, hydrologically active volume of water that neither describes the actual water available through rivers at any time, nor does it describe the useable water in the basin (which could include groundwater not hydrologically linked). It erroneously mentions groundwater management, when many of the worlds aquifers are not hydrologically linked to streamflow and are best described as confined or semi-confined aquifers. Also this work is conducted in the Amazon, where water management and water resources are not primary issues of importance. Instead, the ecosystem and the carbon cycle are much more important topics of concern in the Amazon.
So again, the pairing of the conceptual pitch with the actual work that has been done is a bit mis-aligned for me. I would suggest re-working the introduction a bit to address these issues and remove the water management theme. In fact, I think the article could just begin with the third paragraph, at line 25 on page #2. (BTW: line numbers should be continuous throughout the document, not restarting every page).
5) The rest of the introduction is nicely written, but a bit disorganized. Figures are presented out of order in the text (fig 1b comes before Fig 1a?) and there seem to be some results presented in the introduction (page 5), without context and without explicit mention of the study region and the treatment of the data. This should all (pages 4 & 5) be moved to methods in my opinion and placed in the appropriate ordering for a traditional scientific manuscript.
6) The rest of the introduction is ok, but there should be some explicit discussion of the Tourian et al (2018) paper with a similar title that a previous reviewer mentioned. In my opinion, the paragraph that the author wrote in response to the reviewer should be incorporated into the manuscript introduction.
7) the Amazon is a “basin” not a “catchment”, this should be corrected in the header for section 4 and the text.
8) I don't like that section 5 is titled “Conclusions and Discussion”, which is then followed by two additional sections. The summary statements on “Data driven determination” should be moved, or these sections retitled in a logical manner. Summary and Outlook is a worthy section title for a review paper, but seems inappropriate for a research article, maybe just renaming/combining some of these so that they fit the traditional results/discussion/conclusions format would be easiest?