Subtidal Dynamics in a Tidal River with Limited Discharge

Round 1

Reviewer 1 Report

The manuscript has the potential to advance our understanding of understanding of the spatial and temporal behaviors of subtidal friction and subtidal flux in a tidal river channel with limited discharge. Many of the author's arguments, however, require additional citations. Several examples are provided below:

1. Please discuss little bit more on momentum balance equation in the second paragraph of introduction (before line number 43 "Buschman et al."). I think more references should be added in the introduction section. I strongly recommend authors to cite following article. Reza et al. (2014), An Application of 1-D Momentum Equation to Calculate Discharge in Tidal River: A Case Study on Kaliganga River, Tech. J. River Res. Inst, River Research Institute, 2, 77-86. 

2. In the introduction line number 38 authors mention '... hydrodynamic complexity of a tidal river is further enhanced by the impact of...' I recommend that the authors cite the following sources to justify the influence of water waves in tidal rivers: Sarker, S. (2022) A Short Review on Computational Hydraulics in the Context of Water Resources Engineering. Open Journal of Modelling and Simulation, 10, 1-31. doi: 10.4236/ojmsi.2022.101001.

3. Figure 1 needs to be revised to appear more professional. The software ArcGIS can be used by authors to create more professional-looking figures. 

4. Section 2.3.1 "Spectral Analysis" needs extensive revision. Please explain in detail why power spectrum is necessary for your study. In addition, provide an equation detailing the relationship between Fourier transform and power spectrum. I strongly suggest that authors read, utilize, and cite the following article. Sarker S, Sarker T. Spectral Properties of Water Hammer Wave. Applied Mechanics. 2022; 3(3):799-814. https://doi.org/10.3390/applmech3030047 

5. Figures 2, 4, 6, 7, and 8 lack of professionalism! Make it more professional so that everyone can read. Right now readers will loose their motivation because of figures! I recommend that authors use software such as Python or MATLAB to generate more professional-looking figures.

6. The power spectrum should be plotted on a log-log scale with the correct unit (figure 5). See the article referenced above.

7. Revised the figure 10 and 11 once more. Please also include the p-value in table 1 of the regression tests along with the R2 from figure 10 and 11. 

8. There are a lot of typos in this article that need to be fixed.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Major comments

1. in 2.1 Study site, the general information of water depth, sediment grain size, sediment concentration, salinity, vertical stratification should be added. These factors can influence water density to a certain extent.

2. I can't see any observed data of the time-series of water level, velocity. They are important because they provide the basis for data analysis. 

3. line 138, what is CT sensors, what are their manufacturers and instrument models, and how about their accuracy?  lines 207-211, please explain what caused the modulation of water density? due to salinity, sediment concentration or other factors? Again, more observed data should be shown.

4. line 180-196, how to calculate U0, U1, U2, U3, U'', n''? Despite the authors have given some references, it is better to describe the methods in detail, since these parameters are critical in this study.

5. The discussion part must be reinforced. Presently only the influences of density and gravitational circulation have been discussed. Actually, it is important to clarify the difference between tidal rivers with low and high river discharge. In high discharge case, the morphological evolution induced by high flow, especially by river flood events, would be important for the subtidal dynamics (Xie et al., 2018, 2021, 2022).

 

Minor comments:

1. The label fonts of figure 4,6,7,8,10,11 are too small. Check the match lines for the red diamonds and the insets, 

2. Tables 1 and 2 include limited information. It is suggested to add the R2 values to Figures 10 and 11, and deleted tables 1 and 2.

3. in the abstract, add a sentence to state the implifications of this study for other tidal river systems.

 

References:

Xie, D. F.; Wang, Z. B.; Huang, J. B.; Zeng, J. River, tide and morphology interaction in a macro-tidal estuary with active morphological evolutions. Catena, 2022, 212(8): 106131, doi: 10.1016/j.catena.2022.106131.

Xie, D. F.; Wang, Z. B. Seasonal tidal dynamics in the Qiantang Estuary: the importance of morphological evolution. Frontiers in Earth Science, 2021, 9: 782640, doi: 10.3389/feart.2021.782640.

Xie, D. F.; Pan, C. H.; Gao, S.; Wang, Z. B. Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores. Marine Geology, 2018, 406: 27-33, doi: 10.1016/j.margeo.2018.09.003.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for the revision. 

Reviewer 2 Report

The authors have treated almost all of my comments. I think the ms can be accepted now.