Importance of Flood Samples for Estimating Sediment and Nutrient Loads in Mediterranean Rivers
Round 1
Reviewer 1 Report
The manuscript presents a study on calculated loads (TSS, P, N) in contrasting catchments in S-France. Focus is on the evaluation of two methods - the Flow-Weighted Mean Concentration, and an adapted Flow Duration Rating Curve. The study is based on a comprehensive data set.
Could the manuscript be shortened (overall 25 Figures; see detailed comments; however, reading was not hampered by easily understandable figures).
Discussion section may be improved. Authors may think of discussing also alternative methods for load estimates, as e.g. soil loss/sediment yield calculations in comparison to the presented methods (e.g., based on the RUSLE2015 data base/model), or on-line monitoring methods (e.g. using turbidity as proxy).
A more detailed information on "water quality" monitoring is required in the method section (see comments below). This is a prerequisite for better understanding and interpretation of results.
Detailed comments:
Line 110-119: copy & paste error?
Line 151 ff: More detailed information on "water quality" monitoring is required: sampling procedures, sample preparation, target compounds (TSS, P_tot, N_tot, others?), fractions of compounds in dissolved and particulate species, corresponding analytical methods. This is a prerequisite for understanding and interpretation of results!
Equation 5 refers to Ǭ - abbrevations refers to Q.
Figures 9-17: units for specific loads (tons/km2/year) seem to be not correct (numbers are higher than total loads in Table 6; for all target compounds).
Table 5: it might be of interest for readers to display also Min/Max values (TSS, P, N). Table 5. probably belongs to the results section already.
Line 421ff: Interpretation of the results is hampered by the missing description of analytical procedures in the method section: Differences between methods may depend on proportion of loads in the dissolved or particulate phase. Refers also to discussion of results presented in Table 6.
Line 437: Authors refer to Figure 19 here, not Figure 18.
Figure 20: units for specific loads seem to be correct (but different to Figures 9-17). Figure 20 appears before mentioned in the text.
Line 485ff, Figure 21/22: Interpretation of the results is hampered by the missing description of analytical procedure.
Fig. 21-25: Although possibly helpful, information given by Fig. 21/22 is already visible in Fig. 20, also information given by Fig. 23-25 is already visible in Fig. 20 and Table 6 (Fig. 24 identical to Table 6?)
Discussion section: parts of the discussion are redundant to the results sections (e.g., line 589-594), or to the introduction section (line 579-581). Discussion section could on the other hand be extended towards further possibly interesting items as e.g., dissolved/particulate load fractions (for P, N), and their dependency on frequency of flood sampling; proportions of yearly loads calculated for distinct flow duration intervalls; comparison of findings with findings from different approaches/studies (e.g., based on soil loss, on-line monitring; if availabe).
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
An interesting study investigating the importance of flood samples for estimating sediment and nutrient loads in Mediterranean rivers. The topic of the paper is of interest to the general readers of Water Journal and aligned with the journal's scope. The paper can be considered for publication following the revision described below:
Abstract:
L17 - better to mention the time period of these six years. This will help the local readers to associate the results with the major climatic events.
Intro:
first paragraph - I think you also need to consider the role of mixing in the coastal water bodies in your intro discussions, for example, how dispersion and turbulent eddies can influence the mixing and therefore the water quality (doi.org/10.9753/icce.v35.currents.16;). The overall idea of the above papers is that given the complexity of understanding the mixing processes as a function of contaminant discharge, then having robust and frequent sampling is necessary to understand water quality parameters.
The literature review discusses estimation methods which are good, I think given that you mentioned infrequent data sampling a discussion on how to tackle data scarcity would be valuable for the readers (doi.org/10.1016/j.jwpe.2018.12.010).
Materials and methods:
This section is well-written and contains comprehensive data about study catchments. I wonder if the authors can also include hydrologic data such as average rainfall, and the number of flood events per catchment during the study period? perhaps can be added to Table 3 (just a suggestion).
discussion of Figure 5 - it would be good to see a comparison between the typical EPA method and your proposed approach for the case study data. This is to have a qualitative and quantitative analysis of the impacts of the highest flows representativeness in the calculation of the loads compared to the traditional methods.
Results:
you need to rethink Fig 9 and 10 so that readers can readily compare the methods in one figure and two separate figures.
general comment about figures - pay attention to your units - e.g. figures 13 14 15 and 16 x-axis/ y-axis is km2 and not km2 ... You must revise all figures with wrong unit representations.
The results section contains very detailed information about the study and data collection which is great, I am wondering if some of the figures with secondary importance can be transferred to the appendix section? this can facilitate a concise results section that is not too long for the readers, again a suggestion. The results section contains lots of data and analysis but not very strong in discussing the results in a larger context, and I think the authors must improve discussions of the results during the revision.
Discussion:
This section should be named 'Conclusions'. I would make sure that the contribution of the research from both methodological aspects and the data is clear in this section.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
the manuscript has been improved. I recommend proofreading for minor typo/ language errors.
