A Data-Driven Approach to Stormwater Quality Analysis in Two Urban Catchments

Round 1

Reviewer 1 Report

The paper is very well written. However, some improvements are needed in terms of graphical presentation of the results. Some minor edits are also suggested.

1. What are the benefits of the proposed approach in comparison with the current practice? This need to be explained in the introduction chapter.
2. Table 1: What does the total of 0.29 under volumetric runoff coefficient column represent? Also, "Total Area" in the last row should be changed to "Total". The second comment also applies to Table 2.
3. Table 3: What does the blank data cell under "Overflow duration" column mean? If it was not measured, it should be mentioned as "NA". Otherwise it should be 0.
4. Use of μg/L as an unit for TSS in Figure 3 is not common. Please use the unit of mg/L for TSS.
5. The results presented in Figure 4 are not clear as the authors have presented two sets of data along the same vertical line. The data would be much clearer if the two results are presented separately. It is also a common practice to have a line connecting errors bars with the mean value. I am assuming that the circles represent mean values, but this has not been mentioned.
6. Table 5: The blank row is not necessary.
7. My comments to Figure 4 also apply to Figure 5.
8. Figure 6: Presentation of data is confusing. What does the data presented by the black cross over blue dot mean? Are these two different data points or same data points, but used for two regressions? If the latter is correct, the two data sets should be presented separately. Should the x axis label be ADT/1000? This could be presented as ADT (x1000 vehicles/day) for clarity.
9. The quality of graphs in general is poor. The quality could be improved by adding tick marks to both x and y axes, using proper tick labels and thick lines for axes. Please try to maintain consistency in terms of the use of fonts. In some cases the title might not be required.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

REVIEW REPORT

Title of article: A data-driven approach to stormwater quality analysis in two urban catchments

The study comprises of estimation of stormwater quality of two urban catchments using the StormTac Web model and its comparison with actual measured stormwater quality data. Four stormwater qualities including Total Phosphorous (TP), Copper, Zinc and Total Soluble Salts (TSS) were estimated on annual basis using the model and were compared with the actual measured data. In general, the calculated values of all quality parameters were lower than the estimated values in both catchments. Some explanations for these differences were given in the article.

            The study is suitable for estimating pollutant loads in urban catchments having various quality control facilities. The model uses StormTac database (SUSQD) for modeling the processes. However, there are some limitations in use of this model:

1. The values of volumetric runoff coefficients (Cvol) used in the study are associated with quite high uncertainties.
2. The data base of SQSUD contains data from various sources and for various locations and it may not be representing the actual data.
3. The model uses many site-specific parameters like constituent inflow concentrations, vegetated fraction of the facility, bypassed fraction of runoff, length/width ratio (hydraulic efficiency) of storage layout and detention volume.
4. The model gives output on annual basis, however, if the information can be generated for each runoff event it may be more useful.
5. The model uses TP, Cu, Zn and TSS for quality assessment, however, other quality components like Residual Sodium Carbonates (RSC) and Biological Oxygen Demand (BOD) may also be useful for assessing the pollution levels.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf