A Wet/Dry Point Treatment Method of FVCOM, Part I: Stability Experiments

Round 1

Reviewer 1 Report

I have reviewed the manuscript jmse-1774071 titled “A Wet/Dry Point Treatment Method of FVCOM, Part I: Stability Experiments” by C. Chen, J. Qi, H. Liu, R.C. Beardsley, H. Lin and G. Cowles. In this paper, the authors developed a method to simulate wet/dry areas with an unstructured grid finite-volume coastal ocean model. Numerical experiments were made for an idealized estuary with an intertidal zone in order to evaluate the method paying special to attention to the mass conservation. The influence of the ratio of internal to external mode time steps on the results was analyzed, and criterions to select the times are provided.

In my opinion it is an interesting topic for the readers of the JMSE. The purpose of the work is clear. It describes a relevant aspect of numerical model that have been used in several studies. The authors should include a broader and specially updated literature review allowing to identify the addressed gap in knowledge.

I consider that the paper is well organized. Some aspects of the methodology regarding the numerical experiments analysis could be explained in more detail. The unrealistic velocity shears during the flooding/drying process over the intertidal area was introduced in the discussion but not illustrated nor mentioned in the results.

In summary, I think the paper provide a reasonable methodology to develop this kind of numerical methods and would be a valuable reference for the users of this model. For these reasons I recommend accepting the manuscript after minor revisions.

Detailed comments are listed below.

Eqs. 4 & 5. According to Fig. 2 should it be H+z-hB?

Line 212. What was the criteria to select such an specific value for external time step (4.14 sec)? Is it the condition of line 123?

Line 237. I suppose you evaluated the difference in S and T at every node of the domain for each time step. How does the evolution of the error look like over the domain and along the time?

Line 298. The cited works are not so “recent”.

Line 382. This is an interesting discussion, could it be illustrated based on the numerical experiment results?

Author Response

See the attachment for our responses. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Extensive comments provided throughout paper.

 

Some issues of concern.

1. Abstract and other sections of paper imply that the effort is 3D. The analysis reduces effectively to 2D barotropic tidal problem given the lack of consideration for density and no wind induced forcing.

 2. The selection of the case study (Fig 4) channel driven by tide at one end, with constant channel width and flooded area is never explained. No justification provided for its selection.

 3. The grid system designed for the study is not symmetric normal to the centerline of the channel and inter-tidal area geometry (Fig 4). Its potential impact on the model predictions is not clear. For example, Fig 5, ebb tide panel shows substantial lateral variation.

4. There is no sensitivity study to show impact of grid resolution on model predictions nor if the hypsographic curve is something other than linear (see Fig 2), which it often is for coastal tidally flooded systems.

5. The shape of the free surface interacting with the shoreline in Fig 2 and 4 clearly can't be correct, since slope with respect to seabed is almost 90 degrees.

 6. Might be useful to show some time series of elevation and current at selected locations from center of channel to lateral extent of flood inundation.

 7. Flushing area is used in the summary but never defined. Convention would have this discussed in the form of flushing volumes or flushing times.

Comments for author File: Comments.pdf

Author Response

See the attachment for our responses. We also addressed all questions listed in the manuscript. 

Author Response File: Author Response.pdf