Comparative Use of Hydrologic Indicators to Determine the Effects of Flow Regimes on Water Quality in Three Channels across Southern Florida, USA

Round 1

Reviewer 1 Report

General: The reviewer really enjoyed reading the manuscript, moreover the manuscript made me adopt the method for other study. However, there is a need to revise the manuscript before it is published. Please see the details below.

1. Please provide the meaning of both a and b in the equation (1).
2. The titles for tables and figures, they are sentences rather than table and figure titles. For instance, the title of Table 1 is two sentences. It is suggested to make the titles to be concise and clear. For now they are somewhat too long.

Author Response

Thank you for your review.  Comments as to how your suggestions were rectified are on the attached file.  We hope you find these more than adequate.

Sincerely, 

LJS

Author Response File: Author Response.docx

Reviewer 2 Report

Overall, this study is worthy of publication as it adds to the literature on using C-Q relationships to compare streamflow characteristics by analyzing C-Q relationships for a less-studied type of channel (canal). I do, however, have a few suggestions for revisions. These suggestions are mainly for your figures/tables as well as some organizational suggestions.

General comments:

1. Figure 1 can be removed from the paper because the concepts in the flow chart are discussed in the Introduction and Figure 1 would better be replaced by another figure that shows another aspect of your data.
2. I think a table should be added to the methods section detailing hydrologic and geologic characteristics of the three watersheds. For example, what is the average slope of the basin? What is the size of the watershed? What is the geology? What is the % urbanization or % impervious cover in the watershed? What is the sinuosity of the channel (since you’re comparing a canal to a more natural river)? What year did the channelization of the river occur (if you know this)? This information would give the reader a better ability to understand and visualize your study area.
3. I found the discussion of the PCA and it’s implications to be lacking, so I suggest moving the PCA and Fig 4 to the end of the results and devoting a paragraph or two to its interpretation and implications. I see the PCA more as a summary of all of your results and therefore it should come last in the results rather than first.
4. I found the Q/Qmean discharge threshold statistic to be confusing, especially when you have another variable with the same name (discharge threshold). Furthermore, there is little to no discussion of the Q/Qmean statistic in your discussion section, so perhaps it would be beneficial to remove this statistic from the study.
5. Table 3 should be reorganized to flow logically. The way the columns are ordered now are confusing. I would suggest to reorganize the table as follows with column names from left to right: channel, constituent, Davies’ test, discharge threshold, exceedance probability, Piecewise regression slopes, archetype. -My logic for this is as follows: If I understood correctly, the Davies’ test is to determine IF there was a breakpoint in the data, therefore it’s significance should be listed in the table first because it tells us that there was a breakpoint. Next should come the discharge threshold, since this is your breakpoint. After this should come the exceedance probability of that threshold, finally followed by the regression slopes.
6. I found a couple discussion points to be missing in the discussion. For example: i) can you provide at least a rudimentary explanation for your SC pattern at HC6? ii) Your objective #1 in the introduction discusses “partly-channelized” streams, but there is very little mention of your partly-channelized stream in the discussion. So a little more discussion of you PRC site would be beneficial.

Specific Comments:

Introduction

p2:  Suggest removing figure 1 and adding another figure with your actual measured data – this would be more beneficial than a conceptual figure

p2 line 56: “engender” is a strange word to use here, suggest choosing a different word

Materials and Methods

p4 section 2.1: per comment above, suggest adding in a table describing watershed characteristics (size, geology, slope, sinuosity, % impervious cover)

p5 lines 148-150: do you know when the Hillsboro Canal was drained?

p5 line 158: removed comma from (2004-2018,)

p5 line 164: there is a mistake in your coordinates, double check the spacing/format

p5 line 168: Specific conductivity is abnormal phrasing. Typically the variable will either be electrical conductivity (EC) or specific conductance (SC). Suggest changing phrasing throughout the paper from “specific conductivity” to “specific conductance” and changing label from “SpC” to the standardized “SC”.

p5 section 2.2: How close were the HC6 Q and water quality measurements? Same comment for PRB. It’s hard to tell from your description when you only provide coordinates.

Results

p 6 section 3.1: although you already abbreviated your watersheds in the methods section, can you remind the reader when you first mention each site in the results which type of channel it is?  For example in, the second sentence of your results you could rephrase to “In the PCA, SRS (slough) and PRB (partly-channelized), were noticeably distinguished from HC6 (canal).”  Or something similar because most readers will likely have forgotten which stream is which.

p6 section 3.1: per comment above, suggest moving the PCA later in the paper to the end of the results since this is more of a type of analysis to summarize all of your results and seems out of place when it is introduced in the second sentence of your results section.

p7 Table 1: suggest adding the same parentheses as two comments above to either your table caption or your column headers. For example, your column headers for SRS, PRB, and HC6 could be altered to SRS (slough), PRB (partly-channelized), HC6 (canal). Again, this just helps the reader keep the specific site type fresh in their brain.

p7 Fig 4: discussion of PCA and implication lacking both in results and discussion section, suggest adding a paragraph or two to results/discussion of the implications of the PCA

p7: If you remove Figure 1, I would suggest adding a figure showing comparisons of some of the hydrologic indices for your three sites. For example, you could have a figure showing box plots of the mean, max, min, or a typical storm hydrograph showing how flashy each channel is. This would give the reader a way to visualize how these channels differ in terms of their normal flow characteristics.

p10 Figs 6 and 7: Why are the axis labels so arbitrary? Suggest using whole numbers for all axis labels.  Also, what is happening with your significant figures? Some axis labels have two decimal places, whereas others have one or have whole numbers. Suggest being uniform for all labels.

Discussion

p11 line 316: Suggest splitting the sentence “At PRB, a recurring behavior….” into a new paragraph, so you have three separate paragraphs for your three separate sites

p11: If you add in the new table I suggested with watershed characteristics, then those characteristics (geology, sinuousity, urbanization) should be mentioned in the discussion here as they could provide some explanation for your interpretations of flow regime

p12 line 359: “The dilution at both low flow and high flow…” – this is slightly confusing phrasing because when you look at the graph, it dilutes over the entire range (but I understand you phrased the sentence the way you did because a breakpoint was identified).

p12 line 366-367: SC is highly variable at the HC6 high flows – it ranges from ~450 – 1500 uS/cm at a flow of ~20m3/s. Can you provide at least a one sentence explanation of why this may be?

p 12: Your objective #1 from the Intro states you will discuss and evaluate C-Q relationships in “partly-channelized” rivers, but I find the discussion of this lacking due to the heavier focus on the canal. Suggest adding in a couple sentences about the relevance of C-Q relationships in partly-channelized rivers.

Author Response

Thank you for your detailed review.  Our replies to your comments/suggestions are included in the attached document.  We hope you find these revisions more than adequate.

Sincerely,

LJS

Author Response File: Author Response.docx